Nathalie Aubourg

Béatrice Canel-Depitre

Corinne Renault-Tesson

Sustainable development reports: from global logic to local logic, Case study of Total -Upper Normandy

Introduction

Social responsibility has been brought back into the limelight following new pressure put on companies by the French law on New Economic Regulations (loi NRE), encouraging them to show a positive image. More and more companies dedicate significant resources to showing their commitments, asserting a certain ethical attitude and behaving in a socially responsible way. In this context, several researchers have spent time analyzing large corporations' Sustainable Development Reports (SDR). Amongst the most recent works, some analyze the environmental communication contents of the annual reports of some American corporations (Philippe, 2006), others study societal information disclosed on French logistics service providers' websites (Senkel, 2009) and speeches describing good business practices in terms of CSR (Gond, Igalens, 2008;Béji-Bécheur and Bensebaa, 2009). SDRs are one of the CSR tools and are often used as an "environmental and social showcase". Indeed, the French law 1 on New Economic Regulations is very broad and not very restrictive, thus allowing corporations to use and interpret them in their strategic interest. In all cases, SDRs are part of a globally-targeted institutional communication logic. Furthermore, corporations are more and more interested in local stakeholders in order to take their requirements into account. This is why corporations wishing to guarantee their legitimacy must provide answers which are part of a territorial logic. The originality of this article is to show how a corporation has created a local SDR to meet local stakeholders' expectations. This desire for legitimacy and proximity seems consistent but sometimes difficult to achieve, and leads us to our problem which is based around the following question: how does a corporation link the three components of a triptych founded on a global SDR, the territory and consultation of stakeholders? Amongst the CSR tools, Total's refinery in Normandy has formulated a local SDR named social and environmental report. Can the adaptation of a global SDR into a local SDR, which reveals a bottom-up tendency to consult stakeholders, provide a different kind of information source? Consulting stakeholders is part of a participative approach which is proof of a group learning process. We are firstly going to consider stakeholder management as the fruit of organizational learning. We will then compare the approach initiated by the Normandy refinery to this theoretical construction by focusing on the produced output, the local SDR.

I -THE STAKEHOLDER THEORY AT THE TEST OF LEARNING

The notion of stakeholders2 was born out of one of civil society's new ethical requirements, which demands that corporations account for the social and environmental consequences of their activity. Corporations firstly centered their attention on first tier stakeholders, i.e. those without whom they cannot operate or even survive. But, during the last years of the 20 th century, the notion of stakeholders changed to mean a person or organization with a legitimate interest in a project or an entity. This notion is no longer restricted to distributors, employees, clients (global players); it now includes community members and residents (local players) who are sensitive to the effects on the local economy and its environment. This means that all stakeholders can come together to build a corporation's legitimacy. We will firstly present how to learn to take local stakeholders into account, before wondering about the conditions of this learning process in a systemic view whilst focusing our attention on a specific CSR tool, the SDR.

STAKEHOLDERS AND LEARNING

Corporations, a coalition of stakeholders (Acquier & Aggeri, 2005) with expectations (Freeman, 1984) and diverging influential power (Michell et al., 1997), are greatly dependent and interdependent on other players (Cyert & March, 1970;Crozier & Friedberg, 1977). They can even be considered as being embedded in a social network on which they can rely and in which they actively participate (Piau, 2004). By taking into account the various stakeholders and top management responsibility (Carroll, 1999) as regards the possible damage caused by their activity, corporations make the transition between sustainable development and CSR. The contractual perspective put forward by Friedman (1970) was deemed insufficient by Donaldson & Preston (1995), Carroll (1979), Capron & Quairel (2001). By taking into account the management of externalities, corporations become part of the environment and their embeddedness leads them to be in contact with both contractual and non contractual stakeholders. This social and economic overlapping (Granovetter, 1973(Granovetter, , 1985) ) places corporations in a relational model which will determine their behavior towards CSR. Corporations willing to take on their responsibility whilst taking into account the various stakeholders must accept that their strategic choices may be questioned even though they remain first tier players. This proactive behavior is part of a systems logic in which learning takes place using feedback. Thro their desire to provide an answer to the integration of the various levels of responsibility, corporations take part in an organizational learning process in which interactions between individuals are multiplied and coordinated (Weick & Roberts, 1993). The beginnings of coordination tend to show that the path is still open to reach the learning objectives according to Koenig (1994). Indeed, learning is a group phenomenon of acquisition and development of skills which modify both the way situations are managed and the situations themselves. Koenig (2006) states that the impact of learning increases with the number and diversity of possible interpretations as it widens the range of possible behavior. This is how the joint will of all stakeholders will change the management of situations of environmental damage, thanks to the acquisition of new skills. The learning "by grafting" concept, developed by Huber in 1991, is particularly relevant in the desire to combine the skills of the various players. There are three main characteristics:

-The source of learning comes from a partnership (in our case, a moral contract with several local stakeholders), -The learning catalyst is based on the recognition of an organizational difference (for example, in terms of status, funding model or even mode of election when positions are taken up), -Learning is based on an inter-organizational configuration (corporations, associations, local government, Government departments are all associated with this). This learning may be envisaged from a systemic angle in which the local stakeholders and corporations will jointly develop a local SDR.

TOWARDS A SYSTEMS APPROACH OF LOCAL STAKEHOLDER

MANAGEMENT

The first reports on CSR date back to the Eighties (Parker, 1986). After the four phases identified by Igalens (2005), the years 2000 are characterized by a growing standardization of SDR thanks to the GRI (Global Reporting Initiative). The publication of the guidelines for the publication of reports was qualified as "technocratic", as they were "developed without any democratic control" (Capron, Quairel-Lanoizelée, 2004). We can therefore notice that different methods are chosen by corporations, even those quoted on the stock exchange subject to the French law on New Economic Regulations of 2001. According to the translation by the OCSR 3 , the GRI states that "reporting enables the corporation's contributions to society, to the environment, the opportunity to create economic, social and environmental value of its products and service to be highlighted…. so that the organization can keep and consolidate its right to trade". Corporations go as far as showing their legitimacy, particularly to different local stakeholders, in order to show their reason for being and favor their sustainability. This legitimacy increases when corporations meet stakeholders' expectations and report on the ways in which they do so by reporting in the SDR. The legitimacy theory stipulates that there is a "social contract" which obliges corporations to operate in compliance with society's expectations, and to therefore "justify" their actions by "speeches" addressed to the relevant components of this society (Preston & Prost, 1975;Hogner, 1982;Lindblom, 1994). To this effect, corporations maintain their justification thro the development of the SDR communication tool, they leave a lot of room for their speeches and promise the various stakeholders that they are committed to actions conducted or to be pursued. The desire to report on societal commitment using a local SDR can be considered as a learning process triggered by the corporation with some stakeholders whose representations and mental states differ and can also radically change; this is what the cognitive approach to organizational learning suggests (Argyris & Schön, 1978, 1996). If learning is used as a way of modifying and restructuring action theories, then the systems of rules and beliefs written in the firm's practices are modified. When environmental complexity is added to that, the scope can be widened and the corporation's boundaries extended by consulting several stakeholders. Learning takes place between different kinds of entities with different ways of learning. If the interorganizational nature is present, we can question the conditions in which this learning took place, do the various stakeholders work towards the same goal? If this is the case, we could think that they all contribute to the production of a new communication medium, for example, namely a local development report. This joint construction, Weick's enactment, is organizational learning, as it calls upon and associates several organizations, and is also individual as each stakeholder learns from its relationship with another entity. Interactions between members are the foundation of the system's existence. New proposals emerge, without each individual stakeholder being able to make them individually. Learning refers to group dynamics, which produce joint rules for action (Midler, 1990); it is not the sum of individual knowledge but the product of their interaction. Senge (1990), a precursor of "systems thinking", recommends thinking of phenomena in their entirety, studying the relations between them and integrating the notion of feedback. Morin (1977Morin ( , 1990) ) states that "the simple hierarchy between infra and supra must be abandoned in favor of organizational feedback, where the ultimate product feeds back by transforming what produces it". Without envisaging competition between the different stakeholders, the diversity of learning objects (what is learnt and the characteristics of what is learnt) makes learning part of a process. We can talk about the following process "CSR/legitimacy -consultation of local stakeholders -joint development of a local SDR" in which corporations seek legitimacy with respect to their territory in the face of concerns raised by sustainable development. The figure below formalizes the learning process mentioned above in a systems perspective.

Figure 1: Formalization of the learning process

We want to highlight the corporation's learning process around a management tool. Using the learning concept, we want to find out if the process of joint development of a local SDR has been initiated. The example of the refinery in Normandy will enable us to compare the main theories mentioned above with the reality on the field.

II -LEARNING HOW TO LISTEN TO STAKEHOLDERS: THE CASE OF TOTAL -UPPER NORMANDY

The case study of the Total refinery in Upper Normandy can be used to illustrate the learning process which accompanies the corporation's integration of the local stakeholders' expectations. Total anticipated the obligation of the French law on New Economic Regulations by publishing an SDR as early as 2001. This desire to report was also seen with the wish to communicate locally via the production of a local SDR. We may wonder whether this SDR is not simply the translation of the global SDR at local level. However, large-scale consultation of the local stakeholders can make us think that the Total Group wanted to give the local SDR a different form, to break away from the restrictions related to the production of the global SDR, or even to have a much more refined local focus. We will demonstrate how the refinery in Normandy has freed itself from the regulatory framework of the global SDR in order to ensure its territorial legitimacy, by initiating a consultation of its local stakeholders with the aim of producing a communication plan. The methodology we used is based on the following:

• Five individual, semi-structured interviews held between June 2009 and January 2010. They were held on the premises of the refinery in Normandy with the assistant manager of the sustainable development department for the Total Group and two persons in charge of communication/HR on these premises. These persons had been identified as decision-making players in the local SDR formulation process. Each of these interviews lasted three hours, and their thematic content was analyzed. • The refinery's internal documents, which we were allowed to use. We used documents which were available on the Internet, such as the Total Group's SDRs, as well as the local SDRs made available to local stakeholders and only available in hard copy. The other data came from reports of seminars written by the persons in charge of communication for the Total Group, on the local management of stakeholders and the SRM+ tool which is used to manage local stakeholders. • Our investigation refers to an essentially abductive approach. We start with the facts and wish to connect them to theoretical knowledge in order to understand them. We use Koenig's definition of abduction (1987): "Abduction is an operation which does not belong to logic, and is used to escape from the chaotic perception we have of the real world thro speculations about the relationships between different things […].

Abduction is about making observations about speculations which are then tested and discussed". Abduction is used to build assumptions which are only probabilities or speculations; it is about proposing a rule using case knowledge and consequences. We made use of systems approach theories, learning and stakeholders to conduct this comprehensive approach. Amongst the communication actions envisaged, the process of local SDR formulation will be examined. We will show how this process of territory management is part of corporation learning.

IN SEARCH OF LOCAL LEGITIMACY

The Total Group is established in more than 130 countries, and has shown its will to take on its responsibilities as a major economic player, and ensure that the surrounding communities are able to see the positive impact of this. Local and global acceptability is strengthened (or weakened) by the stakeholders' perception of this territory and the refinery's contribution to its socio-economic development.

In order to obtain the consent of the territories in which it is established, the Group wishes to develop dialog with residents. This desire is strategic as it is a way of obtaining effective permission to operate whilst gaining the trust of the local communities and authorities. Total's representatives play an active part in the authorities provided for in French regulations 4 in order to maintain close relations between the sites and their environment. The Group goes beyond regulatory structures by contributing to the creation of voluntary dialog structures as demonstrated by the Eco-Maires association created in 2005 5 . However, the production of a global SDR cannot be considered as a local dialog tool. The study of SDRs published between 2001 and 2008 show how little attention is paid to local stakeholders. By way of example, the refinery in Normandy, the leading refining cluster in France, subject to the Seveso directive and inspection from the DRIRE 6 , is only mentioned, on average, twice in each SDR for the studied period, despite the fact that it is located in the second largest industrial area in France. The content of the reported information reveals practically nothing but technical, environmental data which is not readily available to the public. If the refinery in Normandy is credible as regards the control of technical and chemical risks, and is greatly involved in the local dialog procedures mentioned above, it must face up to its bad public image. Indeed, there are still concerns over the chronic risks in terms of public health or odor nuisance, for example. In order to improve the societal acceptability of its sites, projects or subsidiaries, the Group developed a management tool called SRM+ 7 (Stakeholder Relationship Management) in 2005. Indeed, up until then, there had been no global approach to the relationships between a site/subsidiary and its stakeholders. Societal actions were handled in a reactive, or even intuitive, way, and more often than not by the Site Director. Since 2005, this tool has been deployed to more than 95 sites in 36 countries. The global aim of the SRM+ methodology is to compare the view of the site's teams with the perception of external stakeholders in order to define plans of action. The main objectives are to bring the societal approach of a particular site or subsidiary into line with stakeholders' expectations, and to initiate dynamics of all top management around the societal stakes. SRM+ uses the metaphor of the funnel to show how convergence and optimality between the internal and external views of the stakes and societal priorities are sought. We will present this tool in the following section.

A PROCESS CONSISTING IN CONSULTING STAKEHOLDERS

A panel of sixty 8 stakeholders was created, divided into 4 categories: "business 9 ", "authorities 10 ", "civil society 11 ", "internal 12 ". A person from outside conducted hotline, telephone warning system, variable message signs, the local government's website, etc.) 6 The DREAL (French Regional Agency for the Environment, Development and Housing) has superseded the DIREN (French Regional Environmental Agency), the DRE (French Regional Development Agency) and the DRIRE (French Regional Agency for Industry, Research and Environment) since the decree published on 28 February 2009: the sole regional pilot of sustainable development policies. 7 In reference to Customer Relationship Management. 8 Out of 220 identified local stakeholders 9 Clients and product users, suppliers, service providers, industrial neighbors, financial & industrial partners, professional organizations, competitors, other group entities, union organizations, external R&D 10 Elected officials, administrations in charge of the environment, social/health administrations, local safety (e.g. fire brigade), other (customary and moral), educational system, hospitals and doctors 11 Owners of land or other assets, users of land, rivers, etc., residents / local communities, associations and NGOs, opinion leaders, the media, general public interviews lasting an average of 2 hours. The societal baseline is made up of fourteen criteria, formed around 3 themes: governance 13 (2 criteria), HSE 14 (7 criteria) and society 15 (5 criteria). For each of these criteria, the stakeholder being interviewed was asked open and/or closed questions enabling the importance of the subject for him/her, his/her satisfaction and expectations to be assessed. He/she then had to give a mark between 1 and 4 depending on the importance of the subject (1 corresponds to very low importance, 4 to a very important stake) and the level of satisfaction in terms of his/her expectations (1 corresponds to a high level of satisfaction, 4 to an extremely low level of satisfaction). The wheel diagram below is used to show the levels of satisfactiondissatisfaction expressed by all local stakeholders consulted at aggregate level.

Figure 2: SRM+ diagram

Source: Total Refinery in-house document So, once the interviews had been summarized, it appeared that the health criterion was very important for all the local stakeholders consulted (solid line) and that Total's solutions to this remain very unsatisfactory (broken line), hence the point of intersection (in the form of a circle) which alerts them to the priority actions. On the other hand, safety is also considered as very important but as 12 Corporate employees, Medical Center, Unions 13 Information, relations and dialog 14 Health, safety, greenhouse gases, preservation of natural resources, biodiversity, waste and recycling, local pollution 15 Nuisance, local economic development, education and training, citizenship, responsibility and product innovation Total's solutions to this are deemed rather satisfactory, no particular attention has been paid to this criterion.

The local stakeholder interviewed was able to express the actions he/she would like implemented with respect to the expectations that he/she had noted. At the end of the consultation, steering committee in charge of the project collated the criteria of the societal baseline in the form of themes. As the site had promised the local stakeholders that it would not disclose the gathered information, table 1 only illustrates some of the expressed expectations. Total then separated the expectations into 2 groups -one for the expectations to be addressed by the site and the other for those concerning the entire industrial area in Le Havre. Table 1 reports the stakeholders' expectations identified during the consultation; it gives the six themes chosen by Total and some examples of mentioned expectations.

Table 1

: Favored themes amongst the expectations of the stakeholders of the refinery in Normandy

Levels of action Themes Examples of local stakeholders' expectations

Expectations concerning the industrial area

Health (of local population)

Better knowledge of the impacts of the industrial area on health, based on impact studies Voluntary initiatives taken by industrialists with respect to local health

Image and attractiveness of the industrial area

Visual impact of the industrial area of Le Havre Quality of air / odors

Support to local economic fabric and local employment

Industrialists requested to combine their efforts to give information about their contribution to local development in a more positive way

Expectations concerning Total

Communication, information and dialog

More information validated by third parties on the impacts on health, safety and nuisances More meetings with residents

Hygiene, safety, environment

Authorities think that there is too much subcontracting More recognition of subcontractors Support of local initiatives Opening up to local offers Amongst the local stakeholders' expectations in terms of communication by Total, requests for more information validated by third parties were made in terms of the impact on health, safety and nuisance, and more meetings with residents. Total initiated a local SDR in 2008, followed by another one in 2009, in order to better inform stakeholders of the refinery's activities. We will analyze the process which led to the production of this local SDR.

THE LOCAL SDR: FROM EXPECTED JOINT DEVELOPMENT TO SIMPLE

PRODUCTION

The local SDRs published16 in 2008 and 2009 each have about forty pages. Their structure is the same as that adopted in the global SDR (an by the director, a presentation of the Total Group, safety, health, environment, human resources and local development); the establishment of the site in Normandy is an addition. Just after the end of the consultation of stakeholders in January 2008, work on producing the first local SDR started, and was finalized during the month of June. At the same time, the steering committee continued its deliberation on the actions to be conducted for stakeholders' benefit. This is why the local SDR was produced by Total's in-house communication department only.

The refinery organized an official ceremony during which this first local SDR was delivered to the stakeholders. All the persons having participated in the consultation received an invitation for July 3 rd 2008 to exchange about the findings of the consultation and key stakes retained. Hardly anybody attended this meeting (around 12 of the 60 local stakeholders consulted and invited were present); we can therefore deduce that the stakeholders voted without thinking (Hirschman's exit). Total had really initiated a process of creating a relationship with local stakeholders thro these consultations (60 persons representative of all local stakeholders consulted); however, this loyal behavior, as defined by Hirschman, was not enough to entail the continuation of exchanges with all the local stakeholders.

In 2009, the second local SDR was published in exactly the same form. The main local stakeholder mentioned in these local SDRs is the personnel (the term "employee" is used 46 times in 2008 in the local SDR of the refinery in Normandy). This confirms the fact that the local SDR is an internal communication tool.

It is right to say that the site's communication department had to face two stakes: improve communication with its local stakeholders and involve the site's employees in a societal approach. Indeed, as underlined by someone in charge of communication of another refinery, in an internal document: "Consultation is a reciprocal exercise which includes sharing knowledge and upgrading. This enables a common base to be created, which is essential if you wish to go farther, towards more tangible things". The dominant culture of a refinery such as the one in Normandy is technical. A participative approach like SRM+ was therefore not self-evident in an environment made up mainly of operators and engineers. It is also interesting to note that the term "employee" was not only used for Total personnel, but also for "employees from outside corporations". It is true to say that nearly half of the persons working for Total come from outside. Terms such as "business associates or employees from outside corporations" or "colleagues from outside corporations" translate the organizational reality of the supply chain. These persons obviously have no legal connection with Total; there is no reporting line in the legal sense, but this sense appears in Total's network operation. Within the supply chain, the question of the chain's (or network's) backbone can be transposed to CSR. The question of distributed control of the chains of players remains. By favoring the personnel, Total neglected the other local stakeholders. The content of these two local SDRs were not assessed afterwards, either by the employees or the local stakeholders. The process followed by the corporation is not part of a systems • The local SDR was created by the corporation, on the basis of the consultation of the local stakeholders without involving them in its formulation.

• The low attendance at the meeting to exchange with the local stakeholders shows that the process is incomplete. • There was no feedback in the sense that the published documents were not assessed. The communication department's desire to start thinking about the local SDR shows the beginnings of a learning process (Fillol, 2007). The emergence of the learning organization appears to be an undetermined, non linear process, created by the players, facilitated by management tools. The refinery initiated the consultation of local stakeholders which was at the origin of the creation of tools, especially the local SDR. It is now a question of continuing this process by associating the local stakeholders with it. Deliberation about the form of such collaboration is under way; one of the chosen ideas is organizational feedback. It must now be made really operational and shared.

We can sense disappointment as regards how the process was managed. The initiator seems to be the only body to have started the learning process. The solitude of the refinery at this stage may be explained by the fact that the process was taken in hand in a very directive way and that the chosen actions (called axes of improvement) were not discussed. We can understand Total's independence in this type of decision making but it might be interesting for Total to try and measure the local stakeholders' perception of the impact of the actions undertaken. Furthermore, this learning process assumes that all the local stakeholders are players. Those associations for the defense of rights which were consulted must be involved not only at the dialog stage but also in the decision making if they are really to be part of the learning process. This involvement is a more sensitive question, and requires thorough learning of the global analysis.

Conclusion

The aim of this article was to report on corporation practice in terms of CSR in a territorial logic. Despite the fact that a lot of research now attempts to analyze the societal information disclosed by corporations about their institutional sites, hardly any is interested in local stakeholder management. The case study of Total in Upper Normandy enabled us to show that the exercise of CSR follows a learning process but is not part of a systems approach. The communications department has planned to involve local stakeholders in the formulation of the next local SDR. It will then be possible to check whether the organizational feedback requested is actually included. The subject of this research project, the local SDR, was one of the expectations expressed by the local stakeholders in terms of communication. It would be interesting to be able to analyze the initiated process for other expectations which have given rise to concrete action by the corporation. The concept of CSR still remains difficult to model (Mullenbach-Servayre, 2007), but the stakeholder theory makes it more operational as it becomes possible for the corporation to put "faces and names" (Carroll, 1991) to the societal requirements to be met. The territorial governance initiatives are thus less based on counter trading and the formulation of substantial standards and more based on the coordination of multiple group interventions oriented towards the definition and creation of a "shared territorial asset" (Dupuis, 2008). Being able to "map" one's stakeholders is not necessarily a sign of having the abilityor the desire -to meet all their expectations. This must not make us lose sight of the fact that the stakeholder theory remains a management tool with the ultimate aim of making a corporation legitimate.

The law no.

2001-420 dated 15 May 2001 on new economic regulations was published in the Official Bulletin dated 16 May 2001; the implementation decree no. 2002-803 dated 3 May 2002.

Stakeholders are defined as any person, groups of persons or organizations: -on which the activity of the entity (site, subsidiary) has a potential, direct or indirect, positive or negative impact -which have a potential, direct or indirect, positive or negative impact on the activity of the entity (site, subsidiary). This definition is close to that given byFreeman & Reed, 1983.

Observatoire de la Responsabilité Sociétale des Entreprises (French Corporate Social Responsibility Observatory)

Such as the CLIC (Local Information and Consultation Committees) set up on all the sites classified as Seveso in France, whose activity is centered on technological safety.

The Eco-Maires association groups together 800 French towns concerned by the setting up of industrial sites. For Total, Upper Normandy, it is a question of identifying the information procedures and the threshold beyond which information must be given (scale of severity and emergency). A list of the inhabitants' concerns has been drawn up and several kinds of tools have been tested to appreciate their effectiveness and accuracy (24/7

Only in hard copy, the refinery's website is under construction and should make the local SDR tool available.


Maxime Ferrera
email: maxime.ferrera@gmail.com

Vincent Creuze

Julien Moras

Pauline Trouv É-Peloux

Keywords: Dataset, Underwater robotics, Monocular Vision, IMU, Pressure, SLAM

We present a new dataset, dedicated to the development of simultaneous localization and mapping methods for underwater vehicles navigating close to the seabed. The data sequences composing this dataset are recorded in three different environments: a harbor at a depth of a few meters, a first archaeological site at a depth of 270 meters and a second site at a depth of 380 meters. The data acquisition is performed using Remotely Operated Vehicles equipped with a monocular monochromatic camera, a low-cost inertial measurement unit, a pressure sensor and a computing unit, all embedded in a single enclosure. The sensors' measurements are recorded synchronously on the computing unit and seventeen sequences have been created from all the acquired data. These sequences are made available in the form of ROS bags and as raw data. For each sequence, a trajectory has also been computed offline using a Structure-from-Motion library in order to allow the comparison with real-time localization methods. With the release of this dataset, we wish to provide data difficult to acquire and to encourage the development of vision-based localization methods dedicated to the underwater environment.

Introduction

Accurate localization is critical for mobile robotics. In open outdoor areas, it can be obtained from Global Positioning System (GPS). However, in GPS-denied environments, such as indoor or beneath the sea surface, robots' position must be estimated from other sensors.

In underwater robotics, the localization problem is often solved by coupling high-grade Inertial Measurement Units (IMU) with compass, Doppler Velocity Logs (DVL) and pressure sensors [START_REF] Paull | AUV Navigation and Localization: A Review[END_REF]). Such solutions, classified as dead-reckoning (DR) localization, are highly dependent of the sensors quality and suffer from unbounded drift. While these methods can be employed quite safely for vehicles navigating in the middle of the water column (i.e. in obstacle free areas), they are not accurate enough for navigation in cluttered areas. In such places, Simultaneous Localization And Mapping (SLAM) methods are preferred. SLAM requires exteroceptive sensors, such as Lidar, sonar or camera, to measure the 3D structure of the environment. From these data, the localization is estimated while a 3D map is progressively built.

Visual SLAM (VSLAM) and Visual-Inertial Odometry (VIO) have been a hot research topic during the past decades (Cadena et al. (2016)). VSLAM consists in estimating localization from visual data, possibly enhanced by complementary sensors, through the mapping of the observed scenes. In ground and aerial robotics, the availability of many public datasets, such as KITTI (Geiger et al. (2012)), Malaga [START_REF] Blanco | The Málaga Urban Dataset: High-rate Stereo and Lidars in a realistic urban scenario[END_REF]) or EuRoC [START_REF] Burri | The EuRoC micro aerial vehicle datasets[END_REF]), to cite a few, has greatly impacted the development of VSLAM methods. Recent algorithms, relying on monocular cameras [START_REF] Mur-Artal | ORB-SLAM: A Versatile and Accurate Monocular SLAM System[END_REF]; Forster et al. (2017); Engel et al. ( 2018)) or on visual-inertial sensors [START_REF] Cadena | Keyframe-based visual-inertial odometry using nonlinear optimization[END_REF]; Mur-Artal and [START_REF] Tardos | Visual-Inertial Monocular SLAM With Map Reuse[END_REF]; [START_REF] Qin | VINS-Mono: A Robust and Versatile Monocular Visual-Inertial State Estimator[END_REF]), have shown impressive results, with centimetric localization accuracy. In underwater robotics, many operations occur near the seabed (biology, Oil&Gas Industry, mine warfare, archaeology...), making visual information available. Nonetheless, in such conditions, the acquired images suffer from degradation like turbidity, backscattering and illumination issues, due to the medium properties. These poor imaging conditions must be accounted for in the development of underwater VSLAM or VIO systems, thus preventing use of the previously cited algorithms [START_REF] Li | Experimental Comparison of Open Source Vision-Based State Estimation Algorithms[END_REF]; [START_REF] Weidner | Underwater cave mapping using stereo vision[END_REF]; [START_REF] Zhang | Robust Visual Odometry in Underwater Environment[END_REF]). Some previous works have investigated the use of monocular camera for underwater localization [START_REF] Burguera | Trajectory-Based Visual Localization in Underwater Surveying Missions[END_REF]; Ferrera et al. ( 2019)), sometimes coupled to low-cost IMU and pressure sensor [START_REF] Shkurti | State estimation of an underwater robot using visual and inertial information[END_REF]; Creuze (2017)), sonars [START_REF] Rahman | Sonar Visual Inertial SLAM of Underwater Structures[END_REF]) or even as a mean of detecting loop-closures in DR systems (Kim and Eustice (2013)). However, the limited amount of public datasets dedicated to this localization challenge prevent a fair comparison of these methods on common data. Moreover, the fact that these data are difficult to acquire, because of the required equipment and logistic, limits the development of new methods. [START_REF] Bender | Autonomous exploration of large-scale benthic environments[END_REF] proposed a dataset containing the measurements of navigational sensors, stereo cameras and a multibeam sonar. [START_REF] Mallios | Underwater caves sonar data set[END_REF] released another dataset dedicated to localization and mapping in an underwater cave from sonar measurements. Images acquired by a monocular camera are also given for the detection of cones precisely placed in order to have a mean of estimating drift. However, in both datasets, the acquisition rate of the cameras is too low (<10 Hz) for most of VSLAM and VIO methods. Duarte et al. ( 2016) created a synthetic dataset simulating the navigation of a vehicle in an underwater environment and containing monocular cameras measurements at a framerate of 10 Hz. Many public datasets have also been made available by the Oceanography community through national websites (https://www.data.gov/, http://www. marine-geo.org). However, these datasets have not been gathered with the aim of providing data suitable for VSLAM or VIO and often lack essential information such as the calibration of their sensors' setup.

In this paper, we present AQUALOC, a new dataset aiming at the development of VSLAM and VIO methods dedicated to the underwater environment. The dataset sequences have been recorded using acquisition systems composed of a monochromatic camera, a Micro Electro-Mechanical System (MEMS) based IMU, a presssure sensor and a computing unit for synchronous recordings. These acquisition systems have been embedded on ROVs equipped with lighting systems and navigating close to the seabed. The recorded video sequences exhibit the typical visual degradation induced by the underwater environment such as turbidity, backscattering, shadows and strong illumination shifts caused by the artificial lighting systems. Three different sites have been explored to create the dataset: a harbor and two archaeological sites. The recording of the sequences occurred at different depths, going from a few meters, for the harbor, to several hundred meters, for the archaeological sites. The provided video sequences are hence highly diversified in terms of scenes (low-textured areas, very texture repetitive areas...) and of scenarios (exploration, photogrammetric surveys, manipulations...). As the acquisition of ground truth is very difficult in natural underwater environments, we have used the stateof-the-art Structure-from-Motion (SfM) library Colmap [START_REF] Schönberger | Structure-from-Motion Revisited[END_REF]) to compute comparative baseline trajectories for each sequence. Colmap processes offline the sequences and performs a 3D reconstruction to estimate the positions of the camera. This 3D reconstruction is done by matching exhaustively all the images composing a sequence, which allows the detection of many loopclosures and, hence, the computation of accurate trajectories, assessed by low average reprojection errors. Along with the computed trajectories, we also provide the list of matched images for each sequence which could be used to evaluate relocalization or loop-closure detection methods. We further include statistics on the 3D reconstruction to assess their accuracy.

With the release of this dataset, we provide to the community the opportunity to work on data difficult to acquire. Indeed, the logistic (ship availability) and the required equipment (deep-sea compliant underwater vehicles and sensors), as well as regulations (official authorizations), can be a barrier preventing possible works on this topic. We are convinced that the availability of this dataset will increase the development of algorithms dedicated to the underwater environment. Both raw and ROS bag formatted field data are provided along with the full calibration of the sensors (camera and IMU). Moreover, the provided comparative baseline makes this dataset suitable for benchmarking VSLAM and VIO algorithms. The rest of this paper is organized as follows. First, we present the design of the acquisition systems used and the calibration procedures employed. Then, an overview of the dataset is given and the acquisition conditions on each site are detailed, highlighting the associated challenges for visual localization. Next, the processing of the data sequences to create a baseline is described. Finally, we detail how the dataset is organized and in which way the data are formatted.

The Acquisition Systems

In order to acquire the sequences of the dataset, we have designed two similar underwater systems. These acquisition systems have been designed to allow the localization of underwater vehicles from a minimal set of sensors in order to be as cheap and as versatile as possible. Both systems are equipped with a monochromatic camera, a pressure sensor, a low-cost MEMS-IMU and an embedded computer. The camera is placed behind an acrylic dome to minimize the distortion effects induced by the difference between water and air refractive indices. The image acquisition rate is 20 Hz. The IMU delivers measurements from a 3-axes accelerometer, 3-axes gyroscope and 3-axes magnetometer at 200 Hz. The embedded computer is a Jetson TX2 running Ubuntu 16.04 and is used to record synchronously the sensors' measurements thanks to the ROS middleware. The Jetson TX2 is equipped with a carrier board embedding the mentioned MEMS-IMU and a 1 To NVME SSD to directly store the sensors measurements, thus avoiding any bandwidth or package loss issue. An advantage of the selfcontained systems that we have developed, is that they are independent of any robotic architecture and can thus be embedded on any kind of Remotely Operated Vehicle (ROV) or Autonomous Underwater Vehicle (AUV). The interface can either be Ethernet or a serial link, depending on the host vehicle's features.

To record data at different depths, we have designed two systems that we will refer to as "System A" and "System B". These systems have the same overall architecture, but they differ on the camera model, the pressure sensor type and the diameter and material of the enclosure. System A (Fig. 1a) is designed for shallow waters and was used to acquire the sequences in the harbor. Its camera has been equipped with a wide-angle lens, which can be modelled by the fisheye distortion model. The pressure sensor is rated for 30 bars and delivers depth measurements at a maximum rate of 10 Hz. System A is protected by an acrylic enclosure, rated for a depth of 100 meters. System B (Fig. 1b) was used to record the sequences on the archaeological sites at larger depths. Its camera has a slightly lower field of view and the lens can be modelled by the radial-tangential distortion model. It embeds a pressure sensor rated for 100 bars delivering depth measurements at 60 Hz. Its enclosure is made of aluminum and is 400 meters depth rated. The technical details about both systems and their embedded sensors are given in table 1.

Each camera-IMU setup has been cautiously calibrated to provide the intrinsic and extrinsic parameters required to use it for localization purpose. We have used the toolbox Kalibr (Furgale et al. (2012(Furgale et al. ( , 2013))) along with an apriltag target to compute all the calibration parameters.

The cameras calibration step allows to obtain an estimate of the focal lengths, principal points and distortion coefficients. These parameters can then be used to undistort the captured images and to model the image formation pipeline, with the following notation:

u v = Π K (R cam w X w + t cam w ) (1)
u v = f x . xcam zcam + c x f y . ycam zcam + c y = Π K (X cam ) (2) with K =   f x 0 c x 0 f y c y 0 0 1   and X cam =   x cam y cam z cam  
where Π K (•) denotes the projection: R 3 → R 2 , K is the calibration matrix, X w ∈ R 3 is the position of a 3D landmark in the world frame, R cam w ∈ SO(3) and t cam w ∈ R 3 denote the rotational and translational components of the transformation from the world frame to the camera frame, X cam ∈ R 3 is the position of a 3D landmark in the camera frame, f x and f y denotes the focal lengths and (c x , c y ) is the principal point of the camera.

As these parameters are medium dependant, the calibration has been performed in water to account for the additional distortion effects at the dome's level. The results of the calibration of the fisheye camera can be seen in figure 2. The camera-IMU setup calibration allows to estimate the extrinsic parameters of the setup, that is the relative position of the camera with respect to the IMU, and the time delay between camera's and IMU's measurements. This relative position is represented by a rotation matrix R imu cam and a translation vector t imu cam . Camera and IMU's poses relate to each other through:

T w cam = T w imu T imu cam (3) with T imu cam . = R imu cam t imu cam 0 1×3 1 ∈ R 4×4 and (T w cam ) -1 = T cam w . = R cam w t cam w 0 1×3 1 ∈ R 4×4 where R imu cam ∈ SO(3), t imu cam ∈ R 3 , T w cam ∈ SE(3), T cam w ∈ SE(3), T imu cam ∈ SE(3)
and T w imu ∈ SE(3). T w cam and T w imu respectively represent the poses of the camera and of the body, with respect to the world frame. T cam w is the inverse transformation of T w cam and T imu cam is the transformation from the camera frame to the IMU frame.

Before estimating these extrinsic parameters, the IMU noise model parameters have been derived from an Allan standard deviation plot, obtained by recording the gyroscope and accelerometer measurements for several hours, while keeping the IMU still. These noise parameters are then fed into the calibration algorithms to model the IMU measurements. As these parameters (IMU noises, camera-IMU relative transformation and measurements time delay) are independent of the medium (air or water), they have been estimated in air. Doing this calibration step in air allowed to perform easily the fast motions required to correlate the IMU measurements to the camera's ones.

All the calibration results are included in the dataset, that is the cameras' models (including the intrinsic parameters and the distortion coefficients), the IMUs' noise parameters, the relative transformation from the camera to the IMU and the time delay between the cameras' and the IMUs' measurements.

Dataset Overview

As explained in section 2, System A was used to record the shallow harbor sequences, while System B was used on the two deep archaeological sites. We propose a total of 17 sequences: 7 recorded in the harbor, 4 on the first archaeological site and 6 on the second site. As each of these environments is in some ways different from the others, we describe the sequences recorded in each environment separately. Table 2 summarizes the specificities of each data sequence. Note that, for each sequence, the starting and ending points are approximately the same. In most of the sequences, there are closed loops along the performed trajectories. Some sequences also slightly overlap, which can be useful for the development of relocalization features.

Harbor sequences

The harbor sequences were recorded in April 2018. System A was embedded on the lightweight ROV Dumbo (DRASSM-LIRMM) with the camera facing downward, as shown in figure 3. The ROV was navigating at a depth of 3 to 4 meters over an area of around 100 m 2 . Although the sun illuminates this shallow environment, a lighting system was used in order to increase the signal-to-noise ratio of the images acquired by the camera. The explored area was mostly planar but the presence of several big objects made it a real 3D environment, with significant relief.

For each sequence, loops are performed and an apriltag calibration target is used as a marker for starting and ending points. On these sequences, vision is mostly degraded by light absorption, strong illumination variations and backscattering. In two sequences, visual information even becomes unavailable for a few seconds because of collisions with surrounding objects. Another challenge is the presence of areas with seagrass moving because of the swell. Moreover, the ROV is sensitive to waves and tether disturbances, which results in roll and pitch variations.

Archaeological sites sequences

The archaeological sites sequences were recorded in the Mediterranean sea, off Corsica's shore. The System B, designed for deep waters, was embedded on the Perseo ROV (Copetech SM Company) displayed in Fig. 4. In the way it was attached to the ROV, the camera viewing direction made a small angle with the vertical line (≈ 20 -30 • ). Perseo is equipped with two powerful led lights (250,000 lumens each) and with two robotics arms for manipulation purposes. As localization while manipulating objects is a valuable information, to grab an artifact for instance, in some sequences the robotic arms are in the camera's field of view. A total of 10 sequences have been recorded on these sites, with 3 sequences taken on the first site and 7 on the second one.

The first archaeological site explored was located at a depth of approximately 270 meters and hosted the remains of an antic shipwreck. Hence, this site is mostly planar and presents mainly repetitive textures, due to numerous small rocks that were used as ballast in this antic ship (Fig. 5a). These sequences are affected by turbidity and moving sand particles, increasing backscattering and creating sandy clouds (Fig. 5b). These floating particles are stirred up from the seabed by the water flows of the ROV's thrusters and lead to challenging visual conditions. A shadow is also omnipresent in these sequences in the left corner of the recorded images, because of the limits of the lighting system. The second visited archaeological site was located at a depth of approximately 380 meters. On this site a hill of amphorae is present (Fig. 6b), whose top is culminating a few meters above the surrounding seabed level. During these sequences, the ROV was mainly operated for manipulation and photogrammetry purposes. While the amphorae present high texture, the ROV was also hovering low-textured sandy areas around the hill of amphorae (Fig. 6a). Because of the presence of these amphorae, marine wildlife has been growing on this site. Hence, the environment is quite dynamic, with many fishes getting in the field of view of the camera and many shrimps moving in the vicinity of the amphorae. In one of the sequence, both arms get in front of the camera. Otherwise, the visual degradation are the same as on the first site.

Comparative Baseline

As the acquisition of a ground truth is very difficult in natural underwater environment, we have used the stateof-the-art Structure-from-Motion (SfM) software Colmap [START_REF] Schönberger | Structure-from-Motion Revisited[END_REF]) to offline compute a 3D reconstruction for each sequence and extract a reliable trajectory from it. By setting very low the features extraction parameters, we were able to extract enough SIFT features [START_REF] Lowe | Distinctive Image Features from Scale-Invariant Keypoints[END_REF]) to robustly match the images of each sequence. Performing a matching of the images in an exhaustive way, that is trying to match each image to all the other ones, allows to get a reliable trajectory reconstruction as many closed loops can be found (Fig. 7).

In Table 3, we provide statistics for each sequence about Colmap's 3D reconstructions to highlight the reliability of the reconstructed models. These statistics include the number of images used, the number of estimated 3D points, the average track length of each 3D points (i.e. the number of images observing a given 3D point) and the average reprojection error. The high average track lengths for each sequence (going from 6.7 to more than 20) assess the accuracy of the 3D points' estimation as it leads to a high redundancy in the bundle adjustment steps of the reconstruction. Moreover, given these high track lengths, the average reprojection error is a good indicator of the overall quality of a SfM 3D model and for each one of the sequences this error is below 0.9 pixel.

The extracted trajectories have been scaled using the pressure sensor measurements and hence provide metric positions. Although these trajectories cannot be considered as being perfect ground truths, we believe that it provides a fair baseline to evaluate and compare online localization methods. Evaluation of such methods can be done using the standard Relative Pose Error (RPE) and Absolute Trajectory Error (ATE) metrics [START_REF] Sturm | A benchmark for the evaluation of RGB-D SLAM systems[END_REF]). Furthermore, we have made available the list of overlapping images (i.e. matching) according to Colmap for each sequence. These files could hence be used to evaluate the efficiency of loop-closure or image retrieval methods.

Table 2. Details on all the AQUALOC sequences and their associated visual disturbances.

Data Sequences Format

As explained in the introduction, the sequences are all available as ROS bags and as raw data. The dataset is split into two folders, one for the harbor sequences and the other for the archaeological ones.

The dataset repository architecture is the following: The calibration files are given in the output format of Kalibr (Furgale et al. (2012[START_REF] Bender | Autonomous exploration of large-scale benthic environments[END_REF]).

The trajectories computed by Colmap for each sequence are available as text files and contain the pose in a translationquarternion form. These files format is the following: #Frame tx ty tz qx qy qz qw 0.

-1.88 2.41 -0.47 0.01 0.06 0.14 0.91 20.

-1.83 2.35 -0.46 0.05 0.64 0.14 0.99 40.

-1.80 2.10 -0.34 0.04 0.58 0.12 0.98 ... The files containing the loop closures detected by Colmap provide information in the following format:

1,1,0,0,1 1,1,1,0,0 0,1,1,0,0 0,0,0,1,1 1,0,0,1,1 ... where a 1 indicates an overlapping between row i and column j, with i and j standing for the frame numbers. Note that only a subset of the images has been used to compute the offline reconstruction with Colmap (1 image out of 5 for the harbor sequences and 1 out 20 for the archaeological ones). Therefore, the frame number given in these ground truth files is the number of their corresponding frame in the full sequence.

About the bag files, each sequence is stored in a separate bag containing the following topics:

• /camera/image raw: Images recorded from the camera. • /barometer node/temperature: Pressure sensor's temperature measurements.

In their raw format, each sequence contains the following data:

For each csv files, the first row starts with a # and then gives the name of the different fields along with their related measurements unit into squared brackets. The following rows contain the values of the measurements. In all these files, the first field is the acquisition timestamp of the measurements. For instance, the depth.csv files look like:

Conclusion

In this paper, we have presented a new dataset of subsea monocular video sequences synchronized with inertial and pressure measurements. This dataset is intended for encouraging the development of localization methods for underwater robots navigating close to the seabed. The sequences have been recorded from Remotely Operated Vehicles in three different environments at different depths: a harbor at a depth of 4 meters, a first archaeological site at a depth of 270 meters and a second one at a depth of 380 meters. The diversity of the recorded environments allowed to capture video sequences with different visual perturbations typical in underwater scenarios. For each sequence, trajectories have been computed offline using a Structure-from-Motion library and are provided as a baseline for performance comparisons of localization methods. The datasets are available both as ROS bags and as raw data. In future work, we plan to perform new acquisition missions in different underwater environments in order to augment this dataset and increase its diversity.

Figure 1 .

 1 Figure 1. The acquisition systems equipped with a monocular monochromatic camera, a pressure sensor, an IMU and a computer along with the sensors' reference frames.

Figure 2 .

 2 Figure 2. Distortion effects removal from Kalibr calibration on one of the harbor sequences. Left: raw image. Right: undistorted image.

Figure 3 .

 3 Figure 3. The Remotely Operated Vehicle Dumbo and the acquisition system A, used to record the harbor sequences.

Figure 4 .

 4 Figure 4. The Remotely Operated Vehicle Perseo, used on the archaeological sites. Credit: F. Osada -DRASSM / Images Explorations.

Figure 5 .

 5 Figure 5. Images acquired on the first archaeological site (depth: 270m).

Figure 6 .

 6 Figure 6. Images acquired on the second archaeological site (depth: 380m).

Table 1 .

 1 Technical details about the acquisition systems.

		Camera sensor	UEye -UI-1240SE
		Resolution	640×512 px
		Sensor	Monochromatic
		Frames per second	20 fps
		Lens	Kowa LM4NCL C-Mount
		Focal length	3.5mm
		Pressure Sensor	MS5837 -30BA
	System A	Depth range	0 -290m
	(Harbor	Resolution	0.2 mbar
	sequences)	Output frequency	5-10 Hz
		Inertial Measurement Unit MEMS -MPU-9250
		Gyroscope frequency	200 Hz
		Accelerometer frequency	200 Hz
		Magnetometer frequency	200 Hz
		Embedded Computer	Nvidia -Tegra Jetson TX2
		Carrier board	Auvidea J120 -IMU
		Storage	NVME SSD 1 To
		Housing	4" Blue Robotics Enclosure
		Enclosure	33.4 x 11.4 cm
		Enclosure Material	Acrylic
		Dome	4" Blue Robotics Dome End Cap
		Camera sensor	UEye -UI-3260CP
		Resolution	968×608 px
		Sensor	Monochromatic
		Frames per second	20 fps
		Lens	Kowa LM6NCH C-Mount
		Focal length	6mm
		Pressure Sensor	Keller 7LD -100BA
	System B	Depth range	0 -990m
	(Archaeo.	Resolution	3 mbar
	sequences)	Output frequency	60 Hz
		Inertial Measurement Unit Same as System A
		Embedded Computer	Same as System A
		Housing	3" Blue Robotics Enclosure
		Enclosure	25.8 x 8.9 cm
		Enclosure Material	Aluminium
		Dome	3" Blue Robotics Dome End Cap

  The archaeological sites sequences do not appear here but are organized exactly in the same manner.

	Harbor site sequences/
	Calibration files/
	camera calib.txt
	imu camera calib.txt
	imu noises.txt
	ground truth files/
	colmap traj sequence X.txt
	...
	colmap detected loop sequence X.txt
	...
	sequence X bag.tar.gz/
	sequence X.bag
	...
	sequence X raw data.tar.gz/
	imu.csv
	mag.csv
	images.csv
	images/
	...

  • /camera/camera info: Images width and height info. • /rtimulib node/imu: Accelerometer and gyroscope measurements. • /rtimulib node/mag: Magnetometer measurements. • /barometer node/pressure: Pressure measurements in millibars. • /barometer node/depth: Depth measurements in meters.

Prepared using sagej.cls

Acknowledgements

The experiments conducted on the archaeological sites have been done in the French waters, in the framework of a research campaign of the DRASSM (French Department of Underwater Archaeology -Ministy of Culture) in accordance with the international regulation (UNESCO Convention on the Protection of the Underwater Cultural Heritage, 2001). The authors are grateful to the DRASSM for its logistical support. The authors acknowledge support of the CNRS (Mission pour l'interdisciplinarité -Instrumentation aux limites 2018 -Aqualoc project) and support of Région Occitanie (ARPE Pilotplus project).

The authors would also like to thank Anthelme Bernard-Brunel for his help in the design of the acquisition systems and Abderrahmane Kheddar for his helpful remarks.

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