J O E ¨l G L A S M A N

Seeing Like a Refugee Agency: A Short History of UNHCR Classifications in Central Africa (1961-2015)

Keywords: Classification, Africa, UNHCR, history

This article looks at the evolution of international refugee protection, using the refugee classifications of UNHCR as an entry point. It is argued that, since the creation of the United Nations High Commissioner for Refugees (UNHCR), access to refugee aid has been globalized but has also become more and more stratified. The UNHCR has expanded its activities beyond the frontiers of Europe, but has also tailored aid for specific groups. This is because protection work increasingly articulates different modes of classifying refugees. Three modes of ordering are explored here in the Central African case: the legal approach, the labour (or developmental) approach and the basic needs (or vulnerability) approach. These modes refer to different regimes of action, different actors of protection and eventually different subjectivities. Each mode of classification, it is argued, is the product of a specific period of the UNHCR's history.

Introduction

In 2014, 189,802 people left the Central African Republic. Thousands crossed the border to Cameroon by car, truck or foot, to the small town of Kenzou. Once there, they applied for refugee protection. Gathering on the dusty football field of Kenzou, near the police station, they waited for a chance to be interviewed by United Nations High Commissioner for Refugees (UNHCR) staff. 1 They waited for days, sometimes weeks, before they finally managed to access the small plastic tables where UNHCR clerks classified them based on their names, sex, age, place of birth, date of arrival, marital status, size of their household, etc. 2 After the long hours of waiting in the heat of the football field, the registration process was relatively brief and smooth. Nevertheless, the atmosphere at the plastic tables was tense. People argued, contested and at times yelled at each other, sometimes to the point that police forces intervened and interrupted the process. This was not just because the new arrivals were exhausted after having been harassed by rebels, custom officers and gendarmes 3 ; rather, after the long journey from places as far away as Carnot, Berberati and Nando, they understood that the few minutes spent with the registration clerk would determine which category they would be assigned to and would shape the next chapter of their life. They knew that classifications matter.

This article argues that, over the last 50 years or so, international refugee protection has become increasingly stratified. International organizations have specialized, rationalized and individualized intervention-and resource allocation. Access to international aid has been broadened, but aid itself has become tailored for specific groups. Stratification has occurred as the UNHCR has expanded its action beyond its original mandate-beyond the borders of Europe and beyond the boundaries of the 1951 Refugee Convention.

In order to grasp this double movement of expansion and stratification, it is necessary to examine specific cases. Most of the examples discussed below are chosen from a broad Central African region-arguably an arbitrary choice (a similar argument could be made based on other cases), but a convenient one since this region has received UNHCR assistance throughout the last 60 years. 4 Central African countries were among the first to receive UNHCR assistance after independence in the early 1960s and continue to use up an important share of the UNHCR budget today (UNHCR 2015: 82).

Fifty Shades of Refugees: Why Classifications Matters

Refugee classification is an emblematic illustration of Pierre Bourdieu's insight that life chances are shaped not only by 'class struggles', but also by 'classification struggles' [START_REF] Bourdieu | La distinction: Critique sociale du jugement de gouˆt, le Sens commun[END_REF]. Refugee classifications determine who qualifies for protection under international law, as well as the quality of the relief aid. Access to refugee camps, tents, food rations and basic items depend on the categories attached to a refugee's name in UNHCR databanks, identity documents and ration cards. Refugee status, family size, special needs: categories shape a refugee's chances in life, the opportunities and constraints. They are important not only for the refugees themselves, but for the system of protection as a whole. Need assessment, programme planning and resource allocation are all based on refugee classifications. The same categories ('refugee', 'single head of household', 'T4 ', etc.) inform interactions between aid beneficiaries and aid workers, aid workers and headquarters, headquarters and donors. They tie together actions, persons and places, thus making collective action possible. They link the micro level of refugee registration in the field to the macro level of UNHCR global policy.

Yet classifications are poorly understood. Most of the time, we simply overlook them. We use refugee classifications to describe the world, assuming that they are as natural and universal as the world itself. We look at reality through the lens of the UNHCR, without even noticing that we are doing so. Refugee classifications are a black box of refugee protection; they play a key role in the entire process, but they function virtually automatically and are barely questioned. 5 They are so ubiquitous in the protection sector that it is almost impossible not to rely on and use them. Refugee statistics are a good example: the 189,802 refugees mentioned in the opening sentence of this text is an aggregated figure based on classifications provided by the UNHCR in Kenzou and other similar towns in the African rainforest. 6 There are good reasons for this, of course. Protection clerks hardly have the luxury of engaging with ontological questions. When registering refugees, they do not usually question classifications. This does not mean that they are naive about their tools. I met a Cameroonian protection clerk, Alain, 7 who, as a sharp observer and member of the same vernacular group as the refugees he was helping, could hold forth for hours about the sophisticated social distinctions of Fulani society. Yet, as a UNHCR staff member and lawyer, he applied the narrow categories of refugee protection in his work. Aid workers do not question the nature of refugee classifications while addressing their needs, anymore than a paediatrician questions the nature of thermometers while examining a sick child. The same is true when institutional partners (United Nations agencies, ministry officials, non-governmental organizations (NGOs), etc.) 8 meet in headquarters, or when UNHCR staff in Geneva aggregate statistical data. Aid workers tend to take social categories for granted, as do consultants, journalists and social scientists.

There is a notable exception to this rule: namely critical anthropologists and those they have inspired. In the last 30 years, these scholars have studied categories as social constructions. Barbara Harrell-Bond has argued that the concept of refugee is 'an artificial category maintained more for the convenience of donors than for the people involved' (Harrell-Bond 1986: xvi). Ge´rard Noiriel has shown that the category of refugee has its historical roots in the localized context of the French Revolution [START_REF] Noiriel | La tyrannie du National: Le droit d'asile en Europe (1793-1993[END_REF], while Liisa Mallki has revealed how, since World War II, humanitarian experts and refugee studies have essentialized it (Malkki 1995b: 496).

Yet, even more importantly, anthropologists have shown that refugees themselves have challenged refugee classifications. While classifications may shape refugees' subjectivities, this happens through a dynamic process of criticism, adaptation and rejection [START_REF] Fresia | Aide humanitaire et production de services publics en Afrique de l'Ouest: le cas de la gestion des populations mauritanniennes re´fugie´es au Se´ne´gal[END_REF][START_REF] Corbet | Ne´s dans les camps. Changements identitaires de la nouvelle ge´ne´ration de re´fugie´s sahraouis et transformation des camps[END_REF][START_REF] Dedenis | La territorialite´de l'espace des camps de re´fugie´s sahraouis en Alge´rie[END_REF][START_REF] Tallio | La fabrique du re´fugie´: L'exemple des camps de re´fugie´s de Dadaab (Kenya) et de Nkondo (RDC)[END_REF][START_REF] Inhetveen | Die politische Ordnung des Flu¨chtlingslagers: Akteure-Macht-Organisation: eine Ethnographie im su¨dlichen Afrika[END_REF][START_REF] Turner | Politics of Innocence: Hutu Identity, Conflict and Camp Life[END_REF][START_REF] Jaji | Social Technology and Refugee Encampment in Kenya[END_REF][START_REF] Jansen | The Accidental City. Violence, Economy and Humanitarianism in Kakuma Refugee Camp[END_REF][START_REF] Ringel | De´sirs et croyances dans l'aide humanitaire: Actions dans les camps de re´fugie´s du HCR a`l'est du Tchad[END_REF]. Far from passively waiting to be labelled, refugees try to make the most of classifications. They adapt their testimony, borrow identity documents and accumulate ration cards. In Kenzou, some refugees sought, and many obtained, the protection of two different international institutions at the same time: the UNHCR and the International Organization for Migration-a double classification that is theoretically impossible under international law. 9

Seeing Like a Refugee Agency 3 Critical anthropology has taken a decisive step towards a better understanding of refugee classification. However, in some cases, the critical analysis loses sight of historical contingencies. The structural critic attempts to uncover power relations hidden behind classification regimes, but misses the historicity of refugee protection. There is a tendency in the critical literature to reduce classification to domination. In the words of Jean-Pierre Godding, for instance: 'The UNHCR considers the refugees more as statistical units, numbers in an administration, perhaps as animals in a zoo' (Godding 1997: 1). This criticism has been instrumental to denaturalizing refugee classifications. However, it is necessary to go further now to grasp the different rationalities at work here. James Scott's notion of 'legibility' is useful in this regard. In Scott's view, a central problem of the modern state is that it arranges populations in order to simplify state functions such as taxation and conscription [START_REF] Scott | Seeing Like a State: How Certain Schemes to Improve Human Condition Have Failed[END_REF]). Scott focuses attention on categories, formats, processes of standardization and rationalization. Similarly, this article focuses on the ways in which the UNHCR arranges populations according to its mandate to protect, and on how UNHCR expertise translates complex, illegible and multiple local claims into standard categories that can be recorded, compared and used. Refugee classifications are like abridged maps of societies, representing the slices of reality that are of interest to international institutions. However, refugee classifications are more than just maps; they shape reality, have juridical and material consequences, and mediate between discourses and everyday actions.

In this article, I suggest that international refugee protection articulates different ways of making societies legible-let us call them 'modes of ordering'. 10 I distinguish between three modes of ordering: a legal approach, a labour or developmental approach and a basic needs or vulnerability approach. (This does not mean that there are only three modes of ordering refugees, of course, but identifying three suffices to make the point that there is more than one. A truly exhaustive study would have to address other modes of ordering, such as family ties, gender, security, etc.) These modes of ordering have a lot in common: they claim to be universally applicable, non-political and to limit the arbitrariness of state sovereignty. They claim to be objective, in the sense of making it possible to take action towards establishing norms, standards or categories that do not depend on who applies them. They are based on categories that enable quantification and evaluation (i.e. number of refugees, hours worked, items distributed, etc.). Moreover, they all mark a clear distinction between protectors and protected. 11 However, these three modes of ordering refer to different terminologies, actors, methods and subjectivities. They emerged from different rationales, problems and places. They cannot all be traced back to a single explanatory principle, 'in last instance'-whether it be 'neo-colonialism ', 'neo-liberalism', 'sovereignty' or 'biopower' (Harrell-Bond 1986;[START_REF] Hyndman | Managing Displacement: Refugees and the Politics of Humanitarianism[END_REF][START_REF] Barnett | Empire of Humanity: A History of Humanitarianism[END_REF][START_REF] Agier | Ge´rer les inde´sirables: Des camps de re´fugie´s au gouvernement humanitaire[END_REF][START_REF] Scalettaris | La fabrique du gouvernement international des re´fugie´s: Bureaugraphie du HCR dans la crise afghane[END_REF][START_REF] Hammerstad | The Rise and Decline of a Global Security Actor[END_REF]. There is no essence to refugee protection, no single unifying logic of classification. Although they are distinct from one another, the three modes of ordering do not constitute homogeneous domains. Rather, they constitute different modes of ordering refugees' problems: various ways of articulating principles, practices and people. They form specific knowledge about refugees, about how they behave and how to relate to them [START_REF] Pols | Enforcing Patient Rights or Improving Care? The Interference of Two Modes of Doing Good in Mental Health Care[END_REF]. 12 They stand for different ways in which international organizations connect the 'problem of refugees' at the global level with the specific fate of individuals.

Let us consider the classification table included in the most well-known UNHCR manual, the Handbook for Emergencies (see Figure 1). At first glance, the table is a coherent grid of categories. To use Scott's terminology, this classification makes complex emergencies legible. The terminology used in the table is consistent with the advice set forth in the Handbook's almost 600 pages, suggesting 'universal standards' to address the 'global problem of refugees' on a 'worldwide' scale. A second look, however, reveals different modes of ordering those in need of protection: there are legal categories ('asylum seeker', 'internally displaced person (IDP)', 'refugee', etc.), professional categories ('student', 'miner', 'nurse', 'weaver', etc.), categories of vulnerability ('disabled', 'blind', 'deaf', etc.), as well as hybrid categories ('traditional leader', 'traditional healer', 'unaccompanied elder', 'woman at risk', etc.). This classification system, in a document meant to guide daily practices, is the result of more than 50 years of UNHCR experience. It is the sedimentation of various layers of history. Consequently, its historicity deserves greater attention.

From Migrants to Refugees: Ordering through Law Refugee protection was initially considered a task for lawyers. Protecting refugees meant giving legal assistance. When the UNHCR was established in 1951, its mandate was to advocate international refugee law. The UNHCR did not provide humanitarian relief, but juridical advice. UNHCR staff identified refugees, distributed travel documents, assisted refugees in obtaining the legal statuses provided by states, advocated for their rights and pushed for the normalization of these procedures [START_REF] Loescher | The UNHCR and World Politics: A Perilous Path[END_REF][START_REF] Hanhima ¨ki | UNHCR and Decolonization in Africa: Expansion and Emancipation, 1950s to 1970s[END_REF][START_REF] Barnett | Empire of Humanity: A History of Humanitarianism[END_REF][START_REF] Gatrell | The Making of the Modern Refugee[END_REF].

Originally, the UNHCR was also limited to protecting European displaced persons. However, by the late 1950s, the number of refugees fleeing from the aftermath of World War II and from the Soviet bloc had decreased. There was little left for UNHCR to do in Europe, and all of the major crises were now happening outside its jurisdiction. In Africa, several thousand people were on the run, yet they were not refugees in the UNHCR sense, since the 1951 Convention relating to the status of refugees restricted the definition of refugees to European refugees fleeing from events that occurred before 1951. Africans fleeing from colonial domination were not considered refugees, nor were those fleeing the aftermath of independence. As a result, during the 1960s and 1970s, the UNHCR pushed for the expansion of refugee law.

Seeing Like a Refugee Agency 5 Africa, of course, had a long history of displacement. Forced migration was a banal reality in pre-colonial African societies 13 : in the nineteenth century, it had been fuelled by the European slave trade on the Atlantic coast, the Fulani Jihad in Northern Nigeria, Sudanese warriors' raids in the Lake Chad area and Zulu expansion in South Africa, while, in the twentieth century, people fled from imperial conquest, colonial repression, army conscription, forced labour, epidemics and famines [START_REF] Harms | River of Wealth, River of Sorrow, the Central Zaire Basin in the Era of the Salve and Ivory Trade, 1500-1891[END_REF][START_REF] Cordell | Des ''re´fugie´s'' dans l'Afrique pre´coloniale? L'exemple de la Centrafrique, 1850-1910[END_REF][START_REF] Guichaoua | Migrants, re´fugie´s et de´place´s en Afrique centrale et orientale[END_REF].

Massive as they were, these displacements were not viewed through the lens of refugee law. Colonial administrators considered migrants a threat to their authority. They complained about 'detribalization', 'floating populations' and 'vagabonds'. 14 They described migration as pathology. 15 Conversely, critics of colonialism considered displacement a sign of colonial brutality. A talented journalist like Albert Londres was able to write powerful pages about forced migration without mentioning refugees. He described the permanent 'exodus' produced by colonialism: '2.6 million Blacks from French West Africa, and many hundreds of thousands from French Equatorial Africa left the French territory' [START_REF] Londres | Terre d'E ´be`ne[END_REF][START_REF] Londres | Terre d'E ´be`ne[END_REF]: 108, 218). 16 But he did not consider them refugees as defined by international law.

Not much had changed by the early 1950s. The 1951 Refugee Convention did not apply to the situation in Africa, so the UNHCR sought other ways to intervene. The High Commissioner argued that UNHCR statutes were broader than the Convention's definition, since the latter related to refugees as individuals, while the statutes related to 'groups and categories of refugees'. He pushed the idea of 'good offices', according to which the UNHCR could provide material assistance to persons beyond the Convention's definition. 17 In 1961, this procedure was formalized in a Resolution of the United Nations General Assembly. 18 A precondition was that states wanting help from the UNHCR were expressly required to lend their 'good offices'. Soon after gaining independence, the heads of states of Burundi and Congo engaged in this procedure.

For the UNHCR, the situation in the Great Lakes region was illegible (in Scott's sense of the term), not only because the agency lacked regional experience and had no staff from Africa itself, 19 but also because the mass displacements in the area were embedded in a large and complex concentric movement of labour migrants, farmers and seasonal workers. 20 All of the countries in the region had received several thousand migrants. Around 14 per cent of the population of Ruanda-Urundi was living in neighbouring countries. In some parts of Uganda, foreigners represented more than a quarter of the population. Around 500,000 Rwandans and Burundians lived in Uganda, and another 155,000 in Tanganyika (Chretien 1978: 72-73;Chre´tien 2000: 243-244;Guichaoua 2004: 112).

The UNHCR considered it too difficult to undertake individual assessments in the region. As a result, it introduced the notion of prima facie refugees: a way to assist refugees through 'good offices' without normal Seeing Like a Refugee Agency 7 determination procedures-and without providing full legal protection. Thus, it created a specific category of refugees for non-Europeans-a distinction that the High Commissioner fully accepted: the 'old refugees' in Europe had needed legal protection, while the 'new refugees' in the 'Third World' primarily needed 'material assistance'. 21 In this way, the juridical category of prima facie refugee distinguished African refugees from European refugees.

Parallel to this, attempts were made to broaden the scope of the 1951 Refugee Convention. In 1967, states agreed on a protocol relating to the status of refugees that removed the words 'as a result of events occurring before 1 January 1951' from the definition of refugee, so that non-European refugees could also benefit from the Convention. However, the UNHCR still considered refugees in Africa to be 'too numerous, dispersed and poor to make individual assessments necessary for Convention refugee designation' and continued to apply prima facie and 'good offices' procedures in the region (Holborn 1975: 440).

African heads of states organized a response. They believed that the 1951 Refugee Convention was based on European values and felt the need for a regional instrument. The 1951 definition of refugee was in fact a product of the European tradition, emphasizing political and civil rights over cultural, economic and social rights [START_REF] Noiriel | La tyrannie du National: Le droit d'asile en Europe (1793-1993[END_REF]. The 1951 Convention defined refugees as persons fleeing due to legitimate fears of persecution, by which they meant 'reasons of race, religion, nationality, membership of a particular social group or political opinion'. 22 The list excluded disease, poverty, natural catastrophe, civil unrest, war or state collapse as entitling individuals for refugee status. Political and civil oppression were seen as a legitimate reason for flight, while material deprivation, drought and hunger were not [START_REF] Hyndman | Change and Challenge at UNHCR: A Retrospective of the Past Fifty Years[END_REF][START_REF] Cambrezy | Re´fugie´s et migrants en Afrique: quel statut pour quelle vulne´rabilite´?[END_REF][START_REF] Barnett | Empire of Humanity: A History of Humanitarianism[END_REF][START_REF] Hathaway | The Law of Refugee Status[END_REF].

In 1969, the Assembly of Heads of State and Government, the highest organ of the Organization of the African Union (OAU), adopted a new convention specifically for refugee problems in Africa. The first article of the 1969 OAU Convention replicated the definition of refugee of the 1951 Convention in terms of indicating political and civil forms of persecution as reasons for flight. However, Article 2 broadened the notion of refugee to also include every person who, owing to external aggression, occupation, foreign domination or events seriously disturbing public order . . . is compelled to leave his place of habitual residence in order to seek refuge in another place outside his country of origin or nationality.

This new definition expressly incorporated generalized violence as a cause for flight [START_REF] Rutinwa | Prima Facie Status and Refugee Protection[END_REF][START_REF] Okoth-Obbo | Thirty Years On: A Legal Review of the 1969 OAU Refugee Convention Governing the Specific Aspects of Refugee Problems in Africa[END_REF][START_REF] Sharpe | The 1969 African Refugee Convention: Innovations, Misconceptions, and Omissions[END_REF]. Some 20 years after the creation of the UNHCR, international refugee law remained the dominant mode for ordering refugees. International law began by distinguishing refugees from the larger groups of migrants and then multiplied the categories of protection. Some refugees were recognized by national state law; others were refugees under the 1951 Convention or under the 1969 OAU Convention; still others were considered prima facie refugees under the UNHCR Statute ('mandate refugees'). In the words of Jennifer Hyndman, this created an 'uneven geography of refugee definitions in international law' (Hyndman 2001: 48).

Not only did 'refugee' encompass several definitions, but a number of other legal categories also competed to include displacement under international and national law: IDPs, asylum seekers, detainees, stateless persons, evicted persons, illegal migrants, war victims, evacuees, expellees, repatriates, returnees and so forth. Of course, people on the run might qualify for several different juridical statuses in succession. For example, having been forced to flee from home while remaining in the same country, they may have become IDPs, only to then pursue their flight into the neighbouring country, thus becoming asylum seekers; there, they may have been recognized first as mandate refugees and later as refugees according to the 1969 OAU Convention and so on. The prism of law made forced displacement representable, but it also created distinctions within the apparatus of protection.

From Refugees to Farmers: Ordering through Work

During the 1970s and 1980s, the UNHCR approach became enriched by new ways of thinking. Notions like work, development and economic integration came to play a larger role in the framing of aid programmes. This is not to say that these notions did not play a role before this period, but rather that their impact on programmes grew rapidly now. The conventional distinction between 'protection' (understood as a legal task) and 'solutions' (understood as longer-term, socially embedded projects) began to blur. While some UNHCR staff continued to uphold a narrow definition of protection limited to legal tasks (such as granting residence permits, travel documents or legal protection against arbitrary arrest; helping individuals become naturalized, etc.), others reframed protection based on the notion of development: the UNHCR Legal Protection division spoke of legal rights, while experts in the Assistance division spoke increasingly of 'material assistance', 'local integration' and 'zonal development' [START_REF] Loescher | The UNHCR and World Politics: A Perilous Path[END_REF].

The notion of work was particularly important for Central African programmes, above all since international refugee law had revealed its limits in non-European contexts. Thanks to the notion of 'good offices', the UNHCR could justify its African programmes to the Executive Committee and General Assembly, thus bypassing the 1951 definition of refugee (Loescher 2000: 106-139). The UNHCR argued that material aid was instrumental to convincing African regimes to accept refugees. This line of argumentation linked 'material assistance' to 'protection', implying that African states would accept refugees within their territories, while UNHCR and Western donors would provide assistance. United Nations High Commissioner for Seeing Like a Refugee Agency 9

Refugees Sadruddin Aga Khan argued that material assistance would 'encourage a generous asylum policy' (Pitterman 1984: 28). Of course, this was a double-edged sword: African states quickly made their willingness to protect refugees conditional upon aid from the international community-that is, unless the UNHCR and donor states were willing to pay for material aid, the African states would not tolerate refugees (Rutinwa 1999: 18;Hyndman 2001: 49).

Taking into account the notions of 'work' and 'development', however, was not just about expanding access. A second advantage was that it gave the UNHCR an idiom for addressing post-colonial African states. In the first decades after independence, there was much talk about economic growth and labour mobilization. African leaders made a tremendous effort to mobilize rural labour because they lacked the financial means to construct new infrastructures and provide services. Various forms of labour mobilization flourished: harambee in Kenya, salongo in Zaire, begakwabega in Tanzania, 'travaux de development communautaires' in Burundi, umuganda in Rwanda and so forth. Since capital and technology were scarce, high-intensity labour was seen as a gateway to development. Obligatory and unpaid work was a recurrent feature in development programmes in rural Africa. In Burundi, every adult was obliged to engage in community work every Saturday from 7 a.m. to 12 p.m. This free workforce was used to build and maintain roads, railways, schools, community centres and irrigated fields. Labour was thought to be abundant, and 'nation building' was given priority. As a result, even though labour mobilization was ambiguously related to the detested colonial compulsory labour, it became standard in nationalist toolboxes [START_REF] Guichaoua | Les travaux communautaires en Afrique centrale[END_REF][START_REF] Cooper | Decolonization and African Society: The Labor Question in French and British Africa[END_REF].

African leaders were not alone in talking about work and development-all of their partners did, too. United Nations agencies such as the Food and Agriculture Organization (FAO), the United Nations Development Programme (UNDP) and the World Bank all had concepts of development and labour (UNHCR 1970). By using similar language regarding work, the UNHCR was able to align its interests with those of bigger and more powerful international organizations. One source of inspiration was the expertise on migration of the International Labour Organization (ILO 1957). Labour migration 'was becoming the focus of concern that forced labour had once been' (Cooper 1996: 218). Migration was seen as causing moral decay, disrupting family life, destroying 'tribal' social structure, reducing moral support for workers and so on. UN experts saw the mobility of labour in Africa as 'abnormal' and disruptive of rural communities. They envisioned labour stabilization as a precondition for improved social security. Stabilization became a consensus among international organizations (Cooper 1996: 365). ILO experts encouraged village planning, family housing, social services and the improvement of rural living conditions-topics that were all familiar to the UNHCR.

UNHCR experts realigned their 'protection' agenda with the interests of post-colonial developmentalism. This had the undertone of a moral project linking protection to work ethic: 'Material assistance,' deputed High Commissioner Prince Sadruddin Aga Khan wrote, 'is meaningful only when the recipients feel they are working hard and trying to establish themselves' (Goetz 2003: 11). At times, this vision was backed by optimistic faith in modernization and economic growth. 'The international effort for assistance to refugees,' declared the UNHCR's Felix Schnyder, 'could be regarded as a useful element in the field of international development aid.' 23 Refugees were seen not as a challenge for humanitarian aid, but as an opportunity for growth. According to one expert, the presence of refugees can act as a catalyst for overall planning and development. Their arrival in a neighboring country can serve as a stimulus to programmes, sponsored and staffed by Africans and non-Africans alike, that strengthen and advance rural development (Matthews 1972: 82).

UNHCR consultants resurrected an old notion that had been used for Asia Minor refugees in Greece (1922), and in India and Pakistan (1948): the notion of 'refugee settlements'. The plan was to integrate refugees in their host country. The UNHCR linked the 50-year-old concept to trendy ILO terminology and to the World Bank concept of 'integrated rural development land settlement schemes', as well as to the 'new land settlement' ideas of US-AID, and opened its first African rural settlement for Rwandans seeking refuge in Zaire in Bibwein 1962 (Kivu). 24 The rural camps were based on agricultural activities and aimed for 'self-sufficiency'. The programmes included irrigation, drainage, as well as the building of roads, accommodations, schools and vocational centres. 'Rural settlements schemes' were seen not only as a solution for arriving refugees, but also as potential catalysts for rural development as a whole. One of the first reports on refugee settlement stated: 'The new settlements would thus become the centers of development for the whole area.' 25 In other words, it was thought that refugee settlements would contribute to economic planning. The strategy of 'zonal development' was implemented in Zaire, Burundi and Uganda, under cooperative agreements between the UNHCR, ILO, FAO and UNDP [START_REF] Betts | Zonal Rural Development in Africa[END_REF].

Where the UNHCR had once provided refugees with travel documents and legal advice, it now gave them tools and seeds. As the number of refugees in the Central African region grew steadily, the importance of material assistance also rose. Between 1959 and1966, some 200,000 Rwandans fled to Uganda, Burundi and Zaire. In 1980, there were 500,000 Rwandans in Uganda and somewhere between 800,000 and 1.4 million in Zaire (Guichaoua 2004: 119-120). The 1966 military coup and the 1972 pogroms against Hutu in Burundi also produced thousands of Burundi refugees fleeing to Zaire, Tanzania and Rwanda. In 1973-74, thousands of Tanzanians fled the authoritarian Ujamaa collectives. As a result: 'In every year from 1967

Seeing Like a Refugee Agency 11 through 1973, African countries received more than half of all international refugee aid' (Pitterman 1984: 28). In the mid-1980s, almost all UNHCR money was spent on material assistance.

From 1961 to 1982, the UNHCR opened 107 settlements in Africa, assisting a total of 940,000 refugees [START_REF] Clark | Older Refugee Settlements in Africa[END_REF]. Rural settlements had become the cornerstone of UNHCR policy regarding African refugees. A report noted:

It is in Africa that the major part of UNHCR's refugee problems are now to be found, and settlement in a rural environment is still the main solution to those problems (UNHCR 1970: 1).

In the 1980s, 96 per cent of the 111 organized refugee settlements in the world were in Africa (Clark and Stein 1985: 2). Both international conferences on Assistance to Refugees in Africa held in Geneva at the time-ICARA I in 1981 and ICARA II in 1984 -reaffirmed the role of local integration and the relevance of organized settlements.

Looking at the question of refugees through the prism of work gave the UNHCR a new way to grasp the issue. 26 It translated a juridical and political problem ('protection') into an economic and social question ('self-sufficiency' and 'integration'). The link between refugee aid and labour consisted of a range of concrete tasks for refugees (draining marshland, cultivating arable land, constructing community centres and water supplies, building roads, etc.). However, it also exposed the UNHCR to new kinds of criticism. UNHCR experts could not hide behind legal determination and identification procedures; they had to engage in discussions about comparative soil quality, culture rotation, chemical fertilizers, poor harvests and tractors breaking down. Critics doubted the economic viability of refugee settlements. Unsurprisingly, the UNHCR assessed its own settlement policy positively. 27 But the settlements experienced the same problems as other rural development projects: climate challenges, inconsistent soil fertility and lack of technology. In various cases, planning experts incorrectly estimated the adequacy of water resources or the quality of the soil.

A first criticism focused on the question of 'dependency'. In the eyes of some observers, UNHCR settlements not only failed to make refugees 'selfsufficient', but actually made them dependent on relief aid [START_REF] Harvey | Dependency and humanitarian relief. A critical analysis[END_REF]. Notoriously, anthropologist Barbara Harrell-Bond accused the UNHCR of fuelling the 'dependency syndrome' of refugees (Harrell-Bond 1986: 151).

A second criticism targeted the obsession with control in the settlements. Refugee settlements often looked like closed camps, limiting their occupants' departures and mobility (Clark and Stein 1985: 10). UNHCR settlement policy resonated with both Western governments' will to contain African refugees and African states' policies of monitoring foreign populations. Some studies argued that refugees living outside the camps were better off than those inside them [START_REF] Kok | Self-settled Refugees and the Socio-economic Impact of Their Presence on Kassala, Eastern Sudan[END_REF]Malkki 1995a;[START_REF] Van Damme | Do Refugees Belong in Camps? Experiences from Goma and Guinea[END_REF][START_REF] Hansen | Angolan Refugee Displacement and Settlement in Zaire and Zambia[END_REF]. Refugees, when they could, avoided living in camps [START_REF] Davis | The Anthropology of Suffering[END_REF][START_REF] Harrell-Bond | Anthropology and the Study of Refugees[END_REF][START_REF] De Waal | Famine Crimes: Politics and the Disaster Relief Industry in Africa[END_REF]. 28 A third criticism was pointed at the political imagination of the UNHCR. Rural settlement programmes were accused of enforcing a sedentary view of societies that aimed for territorial permanence of populations at any price. For critics, refugee settlements seemed to be more about transforming migrants into farmers, townspeople into villagers and groups of refugees into 'communities' than about protecting refugees.

However, the prism of work gave rise to a new mode of classification. An entire new class of people now qualified for inclusion in UNHCR programmes: the 'host population'. This category was part of 'rural settlement schemes', 'regional approaches' and 'zonal development programmes' that emphasized the interests of local populations. 29 UNHCR activities were no longer just about refugees and returnees, but now also considered peasants and their neighbours. A new terminology had emerged that informed programme planning and resource allocation: the terminology of productivity and development and of refugees' ability to become settlers. 30 The best possible refugee for a 'rural settlement' programme was young and able, had farming experience and was willing to contribute to voluntary community work. The elderly, children and persons with disabilities were not the only ones considered more difficult to integrate; so, too, were bureaucrats, students and pastoralists, who were often described as unable or unwilling to adapt to farming. A conceptual opposition took shape, between 'rural refugee' (poorer, less educated, but more malleable and sedentary) 31 and 'urban refugees' (more educated, mobile, living in a more expensive environment and more likely to be politicized). 32 This opposition still informs many workrelated projects today (e.g. 'food for work' projects and 'Income Generating Activities'). The approach through law, legal protection and citizenship was complemented by an approach through work, living standards and communities.

From Refugees to Patients: Ordering through Needs

During the 1980s and 1990s, health specialists became increasingly involved in the UNHCR. The agency included not only lawyers and clerks, but also epidemiologists, paediatricians and nutritionists. Refugee societies were reframed through the prism of needs. People were classified not only according to their legal status, but also according to their vulnerability. Although the UNHCR made a formal distinction between 'material assistance' and 'protection', it became increasingly accepted that meeting refugees' immediate needs was an integral part of protection. 33 This was a conceptual shift: old words gained new meaning. 'Basic needs', for example, was not a new term in the UNHCR vocabulary. But reports from the 1970s referred to 'basic needs' as being met by lawyers-through the Seeing Like a Refugee Agency 13 procedure of asylum, for example. 34 Reports from the 1980s talked about 'basic needs' with respect to rural labour in rural settlements and as a criticism of macroeconomic approaches (ILO 1976); 'basic needs' were a tool to combat poverty. 35 Now, in the 1990s, 'basic needs' referred to the task of 'care and maintenance assistance' (UNHCR 1992). Today, the same notion refers to 'minimum standards' for aid, as defined by a broad range of experts in the areas of health, nutrition, education, shelter, water, sanitation and hygiene (UNHCR 2013: 38-42). Basic needs are now associated with immediate, life-saving services in emergency situations.

This also represented a material shift. Care and maintenance activities now use up the bulk of UNHCR funding for Africa (UNHCR 2015: 91-92). The evolution of refugee camps was emblematic for the emergence of a 'relief model'. Unlike settlements in the 1970s and 1980s, which were based on agricultural work and aimed to push foreign labourers towards local integration, the relief camps of the 1990s and 2000s were like hospitals, treating refugees as patients. Camps tended to be internationally managed and funded, and administrated separately from the surrounding population (Crisp 2006: 12). They relied increasingly on relief handouts and food distribution, and less on subsistence farming. Camps became places of population management, medical intervention and epidemiological analysis. As a result, they have sometimes been referred to as 'bio-political' sites of intervention [START_REF] Agier | Between War and City: Towards an Urban Anthropology of Refugee Camps[END_REF]. 36 Unlike the refugee settlements that gave refugees an opportunity to acquire land and earn a living, the new camps were sites of emergency relief and control.

The concept of needs emerged in a dual context. First, there was a change in asylum policies. For the first two decades or so following independence, African asylum policies were relatively generous. The 1969 OAU Convention established a liberal definition of refugees and made non-refoulement a norm (Crisp 2006: 2). During this period, refugees were rarely rejected at the border or forcibly returned to countries where they faced persecution. Many refugees benefited from a range of legal, social and economic rights in African states; they were offered land to settle and, in some cases, could hope to becomenaturalized. 37 In the 1980s, however, this 'open-door' policy ended. Economic growth slowed or reversed, Structural Adjustment Programmes cut off public spending, official development assistance declined and northern powers introduced harsher asylum policies to prevent refugees from going north. The implicit deal between African states and the international community-generous asylum policies in exchange for material support-was broken. African states became increasingly reluctant to welcome refugees and repatriated them at the earliest opportunity [START_REF] Rutinwa | The End of Asylum? The Changing Nature of Refugee Policies in Africa[END_REF].

The second development was a rising number of refugees. In 1970, there were one million refugees in Africa; by 1990, this figure stood at more than six million. The magnitude and rapidity of flight had changed. The numbers peaked in the aftermath of the Rwandan genocide. Between 14 and 18 July1994, around 850,000 Rwandans crossed the border to Zaire (Borton et al. 1996: 13). In the following two months, some three million Rwandans fled to Tanzania and Zaire [START_REF] Mamdani | When Victims become Killers: Colonialism, Nativism, and the Genocide in Rwanda[END_REF][START_REF] Lischer | Dangerous Sanctuaries. Refugee Camps, Civil War, and the Dilemmas of Humanitarian Aid[END_REF]Bane´gas and Chre´tien 2009;[START_REF] Lemarchand | The Dynamics of Violence in Central Africa[END_REF]. The UNHCR described it as the fastest exodus it had ever witnessed (Rutinwa 1999: 16). Following this crisis, several African countries closed their borders. Instead of offering external protection, these states pushed for keeping escapees in 'safe areas' or 'safe zones' within their countries of origin. In 1996, Zaire closed its borders to Burundi refugees, and Tanzania required all Rwandan refugees to leave [START_REF] Rutinwa | The End of Asylum? The Changing Nature of Refugee Policies in Africa[END_REF]. The number of IDPs grew quickly.

The UNHCR refocused its aid on emergency relief. While it did not stop addressing rights and work issues, it increasingly set standards for urgent aid. First, it turned to food rations, logistics, water and sanitation, shelter, latrine seats and refuse bins (UNHCR 2000). The UNHCR codified emergency norms and guidelines, accumulated emergency stockpiles in Copenhagen and Dubai, and delivered tents, blankets and jerrycans to millions of refugees in dozens of countries. The delivery of basic needs and essential services now absorbs more than half (56 per cent) of the UNHCR budget (UNHCR 2015: 83).

Focusing on emergency relief gave UNHCR new opportunities. Just as the prism of work enabled the agency to address host populations and communities, the prism of needs helped it to rethink the targets of its aid. Instead of devoting itself solely to refugees, it now also attended to 'people of concern', including not just registered refugees, but also IDPs, expellees or returnees. Today, the UNHCR has declared 11 million 'people of concern' (UNHCR 2015), only one-third of which are refugees or asylum seekers. By expanding its original mandate and activities, the organization established itself as the 'lead agency' in humanitarian catastrophes, 38 managing an archipelago of thousands of camps. 39 The UNHCR reframed refugee protection as the 'global governance' of people in need (UNHCR 2011), offering care and support not only to refugees, but also to 'hungry, homeless and poor people worldwide' (Vibeke 2002: 102). 40 Most of the vocabulary regarding needs was borrowed from other UN agencies (such as the World Food Programme, the World Health Organization and United Nations Children's Fund; UNICEF) and humanitarian NGOs. The International Committee of the Red Cross (ICRC) has a long tradition of humanitarian law, which makes it possible to address the question of war victims. The 1949 Geneva Convention distinguishes 'combatants' from 'non-combatants' and offers a classification of vulnerable people that goes beyond 'refugees'. More importantly, NGOs such as Oxfam, Save the Children and Me´decins sans frontie`res have all developed tools to prioritize the medical needs of aid recipients [START_REF] Redfield | Life in Crisis: The Ethical Journey of Doctors without Borders[END_REF][START_REF]The fetishism of humanitarian objects and the management of malnutrition in emergencies[END_REF]. Unlike conventional UNHCR 'screening' of refugees, which seeks to determine people's legal status, the logic of 'triage' used by humanitarian organizations compares bodies and types of pain in order to establish medical priorities.

Seeing Like a Refugee Agency 15 Indeed, sorting populations in terms of need was inspired by the notion of 'triage' used in emergency medicine. 41 Due to the scarcity of resources, the UNHCR learned to classify individuals based on the priorities used in medicine [START_REF] Lachenal | Le triage en me´decine, une routine d'exception[END_REF]. New criteria for action were adopted, based on epidemiology and demographics. 'Protection' now integrated indicators such as mortality rates, nutritional status and morbidity, as well as specific attention to high mortality diseases like cholera. Unlike the conventional approach to protection, which targeted refugees, the humanitarian approach now targeted 'humans' (Geissler et al. 2012: 8). Cooperation between the UNHCR and medical NGOs fostered the discourse on 'global health ' and 'global needs'. This new perspective once again exposed the agency to new criticism. The relief model was accused of being short-sighted. Relief aid in camps has been criticized from an epidemiological perspective (Van Damme 1995), but also for its blindness to political side effects. Refugee camps have been accused of restricting refugees' freedom of movement, favouring undemocratic modes of governance, reducing refugee participation and ultimately endangering protection. Refugee camps have been the target of military attacks (Burundi camps in Tanzania and Sudanese camps in Chad, for example, have been attacked on several occasions) and the site of various forms of violence (from coercion to crime, including domestic violence, armed robbery, forced conscription, sexual violence, arbitrary arrest, etc.) (Crisp 2006: 6). As a result, camps have become emblematic of biomedical migration control. 42 To underscore the dehumanizing effects of refugee relief, scholars have compared camps to prisons, psychiatric institutions and even concentration camps [START_REF] Agamben | Homo sacer. Die souvera¨ne Macht und das nackte Leben[END_REF][START_REF] Agier | Between War and City: Towards an Urban Anthropology of Refugee Camps[END_REF][START_REF] Inhetveen | Die politische Ordnung des Flu¨chtlingslagers: Akteure-Macht-Organisation: eine Ethnographie im su¨dlichen Afrika[END_REF][START_REF] Jaji | Social Technology and Refugee Encampment in Kenya[END_REF].

However, the UNHCR has increasingly embraced the classification of people according to their needs and vulnerabilities. UNHCR activities have been reoriented to address 'people with disabilities', 'chronically ill persons', 'unaccompanied children', 'the elderly', 'teenage mothers', 'single heads of household', 'caregivers', 'survivors of rape' and so on. Beyond merely designating target groups, these categories have also become statistical categories [START_REF] Tallio | La fabrique du re´fugie´: L'exemple des camps de re´fugie´s de Dadaab (Kenya) et de Nkondo (RDC)[END_REF][START_REF] Cambrezy | Re´fugie´s et migrants en Afrique: quel statut pour quelle vulne´rabilite´?[END_REF]. 43

Conclusion

Most of the people gathered on the football field in Kenzou eventually obtained refugee status based on prima facie procedure. 44 They were transported by truck to nearby refugee camps in Timangolo, Mbile´and Lolo. Classifications shaped their experience of camp life. They brought with them the papers issued by the UNHCR-identity documents and ration cards-which entitled them to relief aid. Based on these documents, aid workers handed out plastic sheets, blankets, kitchen sets, jerry cans, soap and food rations. Priority access was given to family tents for women who were single heads of households; to supplementary food for children under five; to sanitary pads for girls over the age of 11 years; to kitchen sets for members of large households; and so on. Camp life was managed according to the logic of classification. Humanitarian organizations are 'inveterate classifiers' (Fourcade and Healy 2013: 562): not only do they distinguish between people who are included in their categories and those who are not, but they also stratify each group along a sliding scale of needs.

Since humanitarian stakeholders often present 'protection' as a unified field of intervention, the plurality of the types of logic involved tend to be overlooked. This idealistic vision is reinforced by the fact that the same word, 'protection', is used to refer to an idea (the moral impetus of treating refugees with decency), a body of legal procedures (framed by international refugee law) and specific institutional boundaries (the UNHCR Division of International Protection, 'protection officers', 'protection assistants', 'protection clerks', etc.). This is why the history of refugee protection tends to be written in linear terms, with ups and downs, moments of progress and crisis, potential and missed opportunities. The conventional narrative presents protection as a cursor on a moral ladder; we follow protected refugees the same way traders follow market prices, anxiously watching stock charts.

But refugee protection is not a one-dimensional process. Indeed, its success may be linked to the very malleability of the notion. Paradoxically, the more the UNHCR has come to reframe the question of migration through the prism of international refugee law, the more it has also engaged with other modes of ordering refugees. As this article shows, though current refugee classifications articulate different modes of ordering, each one has its own inherent logic, history and materiality. The framework of international law was established for European refugees in the aftermath of World War II and had to be adapted to non-European settings. The framework of development and work emerged to enable engagement with African states and development organizations-UNDP, World Bank, ILO, etc.-after decolonization. Finally, the framework of needs and vulnerability became increasingly relevant as the number of refugees rose at the end of the twentieth century, since it allowed humanitarian actors-WFP, WHO, ICRC, MSF, Oxfam, etc.-to become involved. Each mode of ordering corresponded to an attempt to make a new situation legible and to engage with new partners.

In James Scott's study, the notion of 'legibility' is backed by a second notion: 'high modernism'. This term designates the ideology of the modern state and its uncritical self-confidence regarding scientific and technical progress, production and rationality. According to Scott, high modernist planners share an uncritical optimism regarding comprehensive planning and the efficiency of social regimentation. At times, the literature on refugee camps (especially that which draws on Foucault's notion of biopower or Agamben's 'naked life' terminology) tends to treat UNHCR planners as high modernists because of their taste for grid-designed camps, clear boundaries and rigid order [START_REF] Godding | Refugees or Hostages? Population Movements in the Great Lakes Region since 1990[END_REF]Herz 2012).

Seeing Like a Refugee Agency 17 However, Scott studied highly centralized and often authoritarian states such as Prussia, the Soviet Union and socialist Tanzania-bodies that are light-years away from international organizations. The one characteristic that the UNHCR might be said to share with the modern states observed by Scott is the failure to consult the 'people of concern' regarding classification mechanisms. 45 However, UNHCR modes of action are not those of the modern centralized state, because the UNHCR is neither a state nor centralized. With a staff/person-of-concern ratio of 1:5,020 (UNHCR 2015), the UNHCR is a weak institution with a large mandate. It acts in a decentralized and fragmentary manner through a range of other actors-states of varying sizes and strength, UN agencies with different mandates, NGOs with diverse interests, refugees committees with varying representation and so on. 46 Its actions are embedded not in a unified and coherent vision of protection, but in a stratified world of asymmetrical cooperation and distinct solutions. If anything, the UNHCR is more about high connectivity than high modernity. As a result, the strength of the UNHCR is the result not so much of its means of protection as of the quasi-monopoly it holds over the means of classification.

8. Among the organizations assisting refugees in Cameroon (besides state institutions such as the Ministry of Basic Education, Public Health, Social Affairs, etc.) were several UN agencies (International Organization for Migration (IOM), UNICEF, UNFPA, UN Women, WHO, WFP) and many NGOs (including the French Action Contre la Faim, the US-American Adventist Development and Relief Agency, the Ethiopian Africa Humanitarian Action, the Cameroonian Croix-Rouge, the French Croix-Rouge and the Swiss Branch of Me´decins Sans Frontie`res). 9. The UNHCR assists refugees, who are not protected by their state of origin, while the IOM assists migrants, who are still protected by their state of origin. In Kenzou, the IOM ran small camps for people who had fled from the Central African Republic, but had another nationality (i.e. they were neither Central African nor Cameroonian, but from Mali, Niger, Chad, etc.) and helped migrants return to their country of origin. However, since many people had lost their documents while fleeing and international migration is frequent in this context, it was not easy to determine which category applied. Several people at the registration desk in Kenzou attempted to obtain both statuses, because they did not yet know which would be the best option-to be a refugee or a migrant. Also, some Cameroonians applied for refugee status in Cameroon, arguing that they were from the Central African Republic. Refugee status would give them access to UNHCR aid. 10. This typology is based on the reading of secondary sources (listed in the footnotes) as well as on UNHCR grey literature, including UNHCR Reports to the General Assembly and reports from UNHCR Archives, especially: Reports on Central Africa from Fonds 18/Records relating to Assistance/Sub-fonds 2: General technical services Series; UNHCR Headquarter Archives: Report on Central Africa from Fonds 11/Series 02 Classified Subject Files 1971Files -1984;;andUNHCR Handbooks for Emergencies (1982, 2007). 11. This distinction between those who protect and those who are protected is illustrated by the omnipresence of ballistic metaphors in refugee protection ('target population', 'project impact', etc.). 12. The 'modes of ordering' explored in this article are not unlike the 'regimes of truth' in [START_REF] Foucault | Naissance de la biopolitique : Cours au Colle`ge de France[END_REF][START_REF] Foucault | Naissance de la biopolitique : Cours au Colle`ge de France[END_REF]) sense, 'modes of existence' in [START_REF] Latour | Enqueˆte sur les modes d'existence: une anthropologie des modernes[END_REF] sense and 'modes of doing good' (Boltanksi and The´venot 1991;[START_REF] Pols | Enforcing Patient Rights or Improving Care? The Interference of Two Modes of Doing Good in Mental Health Care[END_REF]. 13. Farmers practising shifting cultivation, herders seeking fertile lands, merchants trading with the coast, etc. In the densely populated kingdoms of the Great Lakes region, demographic growth regularly triggered agricultural expansion. In lineage-based societies, when groups grew big, political organizations would splinter: a segment of the lineage would leave the settlement and establish a new compound, hamlet or chieftaincy. Migration was entrenched in a 'logic of schism', itself fuelled by low population density and the perceived abundance of land [START_REF] Kopytoff | The African Frontier: The Reproduction of Traditional African Society[END_REF]). 14. A French administrator of Ubangi-Shari complained about the 'massive exodus' from his circumscription. 'Everyone,' he wrote, 'abandons his tribe, his village, his family and plantations, goes to live in the bush like a hunted animal, to escape from recruiters.' Cf. Administrative Report on Ubangi-Shari, 1902, quoted in Gide (1927: 89-90, translation JG). 15. Colonial administrators attempted to control migration by grouping villages along roads, aggregating populations according to ethnic blocs and establishing fixed

Seeing Like a Refugee Agency 19

Figure 1 A

 1 Figure 1 A Classification Code Used by the UNHCR Sample codes from: UNHCR (2007), Handbook for Emergencies, 3rd edn, p. 175.

Acknowledgements

I am thankful to Roseline Okoro, UNHCR Protection Officer in Yaounde, to Jean Yougouda and the 22 UNHCR staff members and partners (ACF, MSF, UNICEF, WFP, Croix-Rouge) who introduced me to the world of refugee protection in Cameroon in 2014, as well as to the presidents of the 'Comite´s des re´fugie´s' in Kenzou and Lolo and refugees who agreed to answer my questions. Their views greatly inform this article. I am also grateful to Julia Eichenberg, Stefan Hoffmann, Olaf Kleist, Agathe Menetrier, Jill Po¨ggel, Sophie Schlondorff and the anonymous peer reviewers of the Journal for their comments on an earlier version of this text.


Fabrice Dieudonné Atrevi
email: atrevifabrice@gmail.com

Damien Vivet
email: damien.vivet@univ-orleans.fr

Florent Duculty
email: florent.duculty@univ-orleans.fr

Bruno Emile
email: bruno.emile@univ-orleans.fr

3D Human Poses Estimation from a single 2D silhouette

Keywords: Pose estimation, 3D pose, 3D modeling, skeleton extraction, shape descriptor, geometric moment, Krawtchouk moment

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

INTRODUCTION

Recognizing human actions is really challenging for computer vision scientists and researchers since the last two decades [START_REF] Wang | Mining layered grammar rules for action recognition[END_REF]. Nevertheless, human action recognition systems have a lot of possible applications in surveillance, pedestrian tracking and Human Machine Interaction [START_REF] Aggarwal | Human motion analysis: A review[END_REF]. Human pose estimation is a key step to action recognition. A human action is often represented as a succession of human poses [START_REF] Wang | An approach to pose-based action recognition[END_REF]. As these poses could be 2D or 3D, so estimating them have attracted a lot of attention. A 2D pose is usually represented by a set of joint locations [START_REF] Yang | Articulated pose estimation with flexible mixtures-of-parts[END_REF] whose estimation remains challenging because of the human body shape variability, viewpoint change, etc. Considering 3D pose, we usually represent it by a skeleton model parameterized by joint locations [START_REF] Taylor | Reconstruction of articulated objects from point correspondences in a single uncalibrated image[END_REF] or by rotation angles [START_REF] Lee | Human pose tracking in monocular sequence using multilevel structured models[END_REF]. Such representation has the advantage to be Viewpoint-invariant however, estimating 3D poses from a single image still remains a difficult problem. The reasons are multiple. First, multiple 3D poses may have the same 2D pose reprojection. Second, 3D pose is inferred from detected 2D joint locations so 2D pose reliability is essential because it greatly affects skeleton estimation performance. In camera network used in a video-surveillance context, image quality is often poor making 2D joint detection a dif-ficult task, moreover camera parameters are unknown making the correspondence 2D/3D difficult. In this work we propose a new technique for the extraction of 3D skeleton pose assumptions from a single 2D image based on the silhouette shape recognition. This technique is based on the use of a 3D human pose and action simulator. A silhouette database is constructed from this simulator and is used in order to match nearest silhouette and as a results possible 3D human pose. This article presents a silhouette shape description and comparison between different subjects and action steps and show that we can obtain 3D skeleton configuration by using only a single 2D silhouette detection. Section 2 presents related works in the human skeleton and action recognition. Section 3 presents the global framework of the method and the 3D simulation used. Section 4 deals with Krawtchouk shape descriptors applied to human silhouettes. Finally, section 3.1 and 5 present the databases and the obtained results.

RELATED WORKS

There are many methods in the state-of-the-art that deals with the human pose estimation and action recognition. Nevertheless, these tasks are still challenging for computer vision community. Human activity analyses started with O'Rourke and Badler [START_REF] O'rourke | Model-based image analysis of human motion using constraint propagation[END_REF] and Hogg [START_REF] Hogg | Model-based vision: a program to see a walking person[END_REF] in the eighties. Since last decades scientists proposed many approaches. We can categorize these approaches into two main categories: on one hand the methods using 3D information and on the other hand technics using only 2D data. Most of the approaches use a 3D model or 3D detection for estimating the pose of a subject and for action classification. [START_REF] Rehg | Visual tracking of high dof articulated structures: an application to human hand tracking[END_REF]) presented a 3D model-based hand tracking system that can cover the state of a 27 DOF skeleton. Gavrial and al. [START_REF] Gavrila | 3-d model-based tracking of humans in action: a multi-view approach[END_REF]) used a 3D model-based tracking of unconstrained human movement. They used some sequence images acquired from multiple views for recovering 3D body pose of a human. [START_REF] Bourdev | Poselets: Body part detectors trained using 3d human pose annotations[END_REF] estimated the human pose from key points. They used a data set of annotations of human with 3D joins informations inferred using anthropometric constraints for human action classification [START_REF] Maji | Action recognition from a distributed representation of pose and appearance[END_REF]. [START_REF] Hiyadi | Reconnaissance 3d des gestes pour l'interaction naturelle homme robot[END_REF] used the depht information obtained from Kinect sensor and a tracking algorithm for 3D human gestures recognition. Jian [START_REF] Jiang | 3d human pose reconstruction using millions of exemplars[END_REF] proposed an exemple-based method, based on the kd-tree achieves real-time performance, to prune the hypotheses. Ramakrishna and al. [START_REF] Andriluka | Monocular 3d pose estimation and tracking by detection[END_REF] proposed a three-stage process for 3D poses recovering in uncontrolled environment. Valmadre and Lucey [START_REF] Valmadre | Deterministic 3d human pose estimation using rigid structure[END_REF] used deterministic structure from multiple view of motion, based on the related work of Wei and Chai [START_REF] Wei | Modeling 3d human poses from uncalibrated monocular images[END_REF], for 3D pose estimation. These approaches need multiple sensors or specific devices such as time of flight or active camera for acquiring 3D information. These models also, need good parametrization. The second category of approaches, to which our proposed method belongs, used 2D models trained from various images. Baumberg and Hogg [START_REF] Baumberg | Learning flexible models from image sequences[END_REF]) used active shape model to track pedestrians in real world scenes. They used the B-spline as a shape vector for training the model. [START_REF] Wren | Pfinder: Real-time tracking of the human body[END_REF] tracked people and interpreted their behaviour by using a multiclass statistical model of colour and shape to obtain 2D representation of head and hand. [START_REF] Gorelick | Actions as space-time shapes[END_REF] used the solution of Poisson's equation to extract spatiotemporal features such as the saliancy, the orientation of the shape for action recognition and then human pose estimation. [START_REF] Guo | Action recognition in video by covariance matching of silhouette tunnels[END_REF]) used a geometrical normalized vector of dimension 13 for describing the shape of a human. Mori and Jitendra [START_REF] Mori | Estimating human body configurations using shape context matching[END_REF], or [START_REF] Agarwal | Recovering 3d human pose from monocular images[END_REF] used the shape context in their research on human pose estimation. [START_REF] De La Gorce | Model-based 3d hand pose estimation from monocular video[END_REF] estimated and tracked the human hand from monocular video through minimization of an objective function. This minimization is done using a quasi-Newton method, for which they provide a rigorous derivation of the objective function gradient. Yang and Ramanan [START_REF] Yang | Articulated pose estimation with flexible mixtures-of-parts[END_REF] estimated the pose by capturing the orientation of each part with a mixture of templates modeled by linear SVMs. All of these methods focus on 2D image interpretation in order to detect human pose or action. For this purpose, learning is requiered and such algorithms need complex and expensive systems to get the training data set with the ground truth. Our method is based on a very simple silhouette extraction and description. We use the robust Krawtchouk geometric moment to shape analysis in monocular image. For the database, we proposed to use software applications from the open source community. These softwares makes realistic simulation of various human poses and action possible. We have shown in this work that using 3D simulations for learning, without complex machine learning algorithm and with a simple real time shape descriptor we can achieve 3D pose estimation on real data with good accuracy from a unique 2D image.

METHODOLOGY

The proposed approach for pose estimation is based on shape analysis of human silhouette. The method can be decomposed into four parts: (1) simulated silhouette and skeleton database, (2) Human detection and 2D silhouette extraction, (3) silhouette shape matching, (4) skeleton scaling and validation. The workflow is presented Fig. 1.

(1) First, silhouette and skeleton database is built thanks to opensource 3D software (see section 3.1). Such database is composed of human silhouettes and its corresponding 3D skeletons for different kind of actions we want to recognize. So, for a requested silhouette, it'll be possible to find the matching silhouette in the database and then the corresponding 3D skeleton.

(2) 2D silhouettte detection is a well-studied field in machine learning and computer vision. For this purpose we used classical real-time approach proposed by [START_REF] Dollar | The fastest pedestrian detector in the west[END_REF] based on multiscale HOG [START_REF] Dalal | Histograms of oriented gradients for human detection[END_REF]. Once the human silhouette is detected, we converted it in a 128 x 48 pixels image for solving the translation and scale problem.

(3) Silhouette description and similarity measurement is the key point of our methodology. The main objective is to describe accurately the shape of the silhouette. For this task, we used the geometric moment of Krawtchouk because of its robustness compared to Hu, Zernike or Shapecontext descriptors. (See section 4) Based on this descriptor, a characteristic vector is computed for each silhouette in the database. The similarity between characteristic vector is measured with the Euclidean distance given by :

d(z r , z t ) = T ∑ i=1 z r i -z t i 2 (1)
where z r et z t is respectively the characteristic vector of request silhouette and the t th silhouette in the database.

(4) Skeleton scaling and validation. For each silhouette we retrieve a 3D skeleton. This skeleton is scaled to the current silhouette size. At this step we use ground truth simulated database to valide the approach. The confidence score is process by measuring the reprojection error of predicted joints on the silhouette.

3.1 Construction of the 2D/3D matching database

3D human avatar and action simulation

In order to build our simulated humans, we choose to use a professional free and open-source 3D computer graphics software called Blender1 associated with a free software to create realistic 3d human makehuman2 (see Fig. 2). These avatars can be animated thanks to motion capture data in order to simulate very realistic actions.

Database construction

In the 3D computer graphics software, we positioned on an emisphere a virtual camera looking at the subject. For each movement of the avatar, we record both: 2D image and silhouette (see fig 3), 3D camera poses and 3D joints and bones poses. As a result for each subject's pose we can collect the detected silhouette related to its 3D skeleton which contains 19 bones. We recorded in 4 subjects with different phenotypes and for 4 differents animations: walk cycle, basket action, jumb and climb. As a result, we obtained 2925 couples silhouette / 3D skeleton.

For each silhouette, we calculated the feature vector of the shape descriptors presented in section 4 and the 2D poses of reprojected joints for quantitative evaluation of the method. The n-th order of Krawtchouk polynomial is based on the hypergeometric function and is defined as:

K n (x; p, N) = N ∑ k=0 a k,n,p x k = 2 F 1 -n, -x; -N; 1 p
(2) where x, n = 0, 1, 2, ..., N et N > 0, p ∈ (0, 1) and the hypergeometric function defined as:

2 F 1 (a, b; c; z) = ∞ ∑ k=0 (a) k (b) k z k (c) k z k k! (3) (a) k = a(a + 1)...(a + k -1) = Γ(a + k) Γ(a) (4)
Equation ( 4) is the Pochhammer symbol.

The set of (N+1) Krawtchouk polynomial forms the complete set of discrete basis functions with weight function

w(x; p, N) = N x p x (1 -p) N-x (5)
and satisfies the orthogonality condition : In order to eliminate the large variability in the dynamic range, a normalization process is applied. Then, the set of normalized (weighted) Krawtchouk polynomials is defined by [START_REF] Yap | Image analysis by krawtchouk moments[END_REF] as:

Kn (x; p, N) = K n (x; p, N) w(x; p, N) ρ(n; p, N) (7)

Krawtchouk Moment

Krawtchouk moment is firstly used in image analysis by P.T Yap and al. [START_REF] Yap | Image analysis by krawtchouk moments[END_REF]. Based on the weighted Krawtchouk polynomials, the (n + m) order of Krawtchouk moment for an N x M image with intensity function f (x, y) is defined as:

Q nm = N-1 ∑ x=0 M-1 ∑ y=0 Kn (x; p1, N -1) Km (y; p2, M -1) f (x, y) (8)
The parameter p1 and p2 can be viewed as a translation factor. Indeed, if p = 0.5 + ∆p, the weighted Krawtchouk polynomials are shifted by about N∆p. The direction of shifting relies on the sign of ∆p, with the polynomials shifting along + x direction when ∆p is positive and vice versa. This property allows to extract the local properties of an images. For software like Matlab, there is a matrix form of the Krawtchouk moment. In matrix form, it is defined as:

Q = K 2 AK T 1 (9) where Q = {Q ji } i, j=N-1 i, j=0 , K v = { Ki ( j; pv, N -1)} i, j=N-1 i, j=0 and A = { f ( j, i)} i, j=N-1 i, j=0

Feature extraction

For a given image of human silhouette, we used Krawtchouk moment to describe the shape of the human belong to the image. That means to calculate the characteristic vector of the image with different values of the moment. Thanks to the ability of Krawtchouk moment to extract feature of specific regions of the image, we divided each silhouette in two parts (up and bottom) (fig. 4) with the parameter p1 = 0.5, p2 = 0.1 (for the up) and p1 = 0.5, p2 = 0.95 (for the bottom). Then, we calculated two characteristic vectors and combined them to get one vector descriptor. Each human silhouette extracted is converted to a common space 128 x 48 to get the invariance to translation and scale. For rotation invariance, we supposed that the vertical is preserved. According to some related works, we chose to calculate Krawtchouk moment with parameter (m = n). In order to find the best value of n, we used a database with 600 simulated silhouettes and done cross validation over all. The fig 5 show that from order (n = m = 24), we got a stable and best accuracy for pose recognition. So, the final feature vector has 48 dimensions.

EXPERIMENTS

In section 3.1 we have shown that for each 2D image of silhouette of the database, we store both the silhouette vector descriptors and the associated 3D skeleton composed of 19 joints. Then, for a test image with extracted silhouette, similarity is computed between the processed vector of descriptors and database descriptors using the Euclidian distance. As a result we extract the corresponding silhouette in the database and its joints 3D poses. Note that the approach does not only give the more suitable silhouette but gives in a classified way the N th most probable silhouettes. In order to evaluate the given result, we used the simulation. By knowing the real skeleton of the test image, we can process the reprojection error of the estimated 3D joints. According to experimental result, when the mean error is less than 5 pixels, the pose of the result is considered similar to the pose of the request silhouette. For this empiric threshold, the difference between two silhouettes is hardly visible for a human. The aim of this experience is to see if the shape descriptor can perfectly encode a silhouette and make the difference between closed postures. The silhouette in the database can be very similar because we extracted it from a video of the motion, so two near frames provide a very similar silhouette. For std = 0, we have the original silhouette and for std > 0, the Gaussian white noise is added on the silhouette. Figure 7 shows that the more the std increases, the more the recognition accuracy decreases. For this test we used a training data set composed of 2925 and a testing test of 608 silouhettes. For a single neighbour (N = 1), with std = {0, 1, 2, 3}, the recognition rate is respectively RR = {98.81, 96.43, 74.6, 44.84}. But, if we augment the number of N assumption returned by the program, the recognition rate grows up quickly. For N = 7 and std = {0, 1, 2, 3}, the RR are {100, 100, 96.43, 73.41}. Considering that the silhouettes are very similar and the noise very strong, the method gives very good results. For the rest of the article we will consider N = 7 first silhouettes given by the matcher.

Representativity and descriptor robustness to noise

In order to estimate the 3D extracted skeleton, we use the same request silhouette as for previous experiment. For each extracted silhouette, we process the reprojection error and evaluate the accuracy for different value of N. The Figure 8 shows skeletons estimations from a single monocular image. For this result, the reprojection error of the first image (human walking) is 2.4739 px and that of the second image (human in cross position) is 1.2614 px. This means error show that the retrieval pose is near to the original pose. Note that, in the database, there a no avatar with the similar appaerance, so this error is reasonable.

The images that we used as request in fig 8 are simulate image. So, we got a perfect result with low reprojection error. The result of this 3D skeleton extraction of fig 9 is perfect because this pose is unique and easy to find. The silhouette extraction is too easy because we have a static and uniform background.

In fig 10, we used a real world image extracted from a walking action video. The pose that we choose is similar but not exact with pose in the learning database. So, we don't expect to get a very simular 3D pose as result, but some pose similar. The result show a good result in term of the shape of the pose. But, confusion was made between right and left foot and arm.

In order to evaluate the stability and therobustness of our approach, we considered the successive detections during a complete movie of the movement. Note that there is no use of the time line and each frame is processed independently. Figure 11 (a) shows the tracking results of four human's joints during the execution of the climbing motion. The red curve show the real position over time and the green curve show the estimate position over time. We can note that the shape of different curves is the same. That means that the successives detections are stable in time and that our shape descriptor is reliable. We can note that there is an offset due to shape scaling. The means error over the motion execution is 1.9765 px. Figure 11 shows that the shape of the curve changes as a fonction of the motion. The means error obtained form the jump motion is 1.9892 px. This discrimination factor confirmed that the 3D poses can be used for actions classification in a video.

Application to action recognition on real data

We used the same shape descriptor for human action classification in video, with the public Weizmann database (see Figure 12). As we do not use temporal information, our method consists in matching each frame to an action class and took the class with the highest associated rate as the class action.

The database is a collection of 90 low-resolution (180 x 144, deinterlaced 50 fps) video sequences showing 9 different people, each performing 10 natural actions: run, walk, skip, jumping-jack, jump, gallopsideways, wave-two-hands, waveone-hand, or bend. On Weizmann data base, we made a cross validation with the different movements and with the different phenotypes. In each case and for each frame, we apply our shape matching method to each frame. As the resulting silhouette from the database belongs to a specific movement class we simply count the number of occurencies. The more represented class is then considered as the detected movement.

Based on this very simple workflow, we got 71.66% of good action classification. The confusion matrix is shown on the fig. 13. Of course, this accuracy rate is lower than the recent accuracy obtained on the same database (Blank 99.64% [START_REF] Blank | Actions as space-time shapes[END_REF] and Gorelick 97.83% [START_REF] Gorelick | Actions as space-time shapes[END_REF]). But both of these approach used space-times cubes to analyse the motion while we do not consider yet the temporal correlation between successives frame. According to Gorelick et al.: many successive frames from the first action (about run) may exhibit high spatial similarity to the successive frames from the second one. Ignoring the dynamics within the frames might lead to confusion between the two actions. As the approach does not take into account time dimension, frame to frame comparison leads to misclassification for these very similar frame to frame actions: run, skip and jump.

In future work, we will use our proposed approach combined with the multi-hypothesis tracking techniques (with N neighboors) to improve the accuracy of action classification. By this way, we will take into account the temporal information and the dynamic of the action. tion to 3D pose estimation and action classification have been presented. In our work, we tested different moment order and selected the best suitable for our approach. We compared our approach with some related work in action classification and we concluded that this approach can be improved by using multihypothesis tracking during action identification and classification. In future work, we will use a combination of local and global shape descriptor for improving the pose estimation, and use the estimated poses to construct an action model for activity classification.

ACKNOWLEDGE

This work is part of LUMINEUX project, supported by the Regional Centre-Val de Loire (France). The authors would like to acknowledge the Conseil Regional of Centre-Val de Loire for its support.

Figure 1 :

 1 Figure 1: Human pose estimation methodology.

Figure 2 :

 2 Figure 2: 3D simulated avatar and its associated skeleton In these softwares, we simulate different human avatars with different morphologies and clothes and animate them with different realistic motions taken from the CMU motion capture database 3

Figure

  Figure 3: Human silhouette extracted

  p, N)K n (x; p, N)K m (x; p, N) = ρ(n; p, N)δ nm (6) where ρ(n; p, N) = (-1) n 1-p p n n! (-N) n and δ nm is the Kronecher function.

Figure 4 :

 4 Figure 4: Krawtchouk polynomial for up and bottom

Figure 5 :

 5 Figure 5: Accuracy of cross validation with differents value of n

  Silouette extraction is still an active reseach field. It is well known that extraction is subjected to noise. First point was to check our descriptors robustness to noise. For this, we conducted experiments with two databases of simulated data for a human avatar with different morphology and different actions. The first database contains 2925 training data with Gaussian noise around the contour of the shape and the second database contains 608 unlearning data. The aims of this experience is to evaluate the capacity of shape descriptors to encode various shapes with different value of the standard deviation of Gaussian noise. Considering x 0 = [0, 0] the center of the silhouette, let x i = [ρ i , θ i ] the polar coordinates of a contour point.The noise ∆σ is applied on ρ i . ∆σ → N (0, std) with std = {0, 1, 2, 3}. Example of noised silhouettes are presented on figure 6.

Figure 6 :

 6 Figure 6: Noised silhouettes with ∆σ → N (0, std) and std = {1, 2, 3}

Figure 7 :

 7 Figure 7: Histogramm of accuracy: colors represent the noise amplitude resp. {0, 1, 2, 3} pixels. The abscisses represent the number N of neighboors considered {1, 3, 5, 7}.

Figure 8 :

 8 Figure 8: 3D pose estimation result: Left, the resquest silhouette and from left to right, the 3D estimated skeleton from various viewpoints

Figure 9 :

 9 Figure 9: Real world data 1

Figure

  Figure 10: Real world data 2

Figure

  Figure 11: Tracking result

Figure 12 :

 12 Figure 12: Some images of Weizmann database

https://www.blender.org/

http://www.makehuman.org/

The data used in this project was obtained from mocap.cs.cmu.edu.