Nicky Gkaretsa
email: garetsa.nicky@gmail.com

Lazaros Iliadis
email: liliadis@fmenr.duth.gr

Stephanos Spartalis

Antonios Kalampakas
email: akalampakas@gmail.com

Fuzzy Classification of Cyprus Urban Centers based on Particulate Matter concentrations

Keywords: Z, S, Pi, Gama, Exponential membership functions, Fuzzy Classification, Particulate Matter air pollution

This research aims in the design and implementation of a flexible Computational Intelligence System (CIS) for the assessment of air pollution risk, caused by PM10 particles. The area of interest includes four urban centers of Cyprus, where air pollution is a potential threat to the public health. Available data are related to hourly daily measurements for 2006, 2007 and 2008. This Soft Computing (SC) approach makes use of distinct fuzzy membership functions (FMFs) in order to estimate the extent of air pollution. The CIS has been implemented under the MATLAB platform. Some interesting results related to each city are analyzed and useful outcomes concerning the seasonality and spatiotemporal variation of the problem are presented. The effort reveals the severity of air pollution. Risk is estimated in a rather flexible manner that lends itself to the authorities in a linguistic style, enabling the proper design of prevention policies.

Introduction

The presence of any type of pollutants, noise or radiation in the air, can have a potential harmful effect in the health of all living creatures and might make the environment improper for its desired use. Globally, air pollution is considered responsible for a high number of deaths and it also causes several deceases of the breathing system, mainly in urban centers [START_REF]The Department of Labour Inspection (DLI)[END_REF]. PM10 are floating particles that have a diameter higher than 0.0002 μm and smaller than 10μm [START_REF] Garcia | Artificial Neural Network Models for Prediction of Ozone Concentrations in Guadalajara, Mexico[END_REF], [START_REF] Iliadis | Intelligent Agents Networks Employing Hybrid Reasoning: Application in Air Quality Monitoring and Improvement[END_REF]. Immediate actions have to be taken, as studies in the USA have shown that a slight increase of the PM levels only by 10 μg/m3, can increase mortality by 6%-7% [START_REF] Sumathi | Computational Intelligence Paradigms Theory and Applications using Matlab[END_REF].

Literature Review

Numerous papers describing various Soft Computing approaches have been published in the literature lately. Olej, et al., 2010 [16], have developed a FIS (Mamdani) towards air pollution modeling. Garcia, et al., 2010 [7] used a neural system and Artificial Neural Networks (ANNs) for the estimation of air quality related to O3. Iliadis and Papaleonidas, 2009 [START_REF] Iliadis | Artificial Neural Network Modelling of the surface Ozone Concentration[END_REF], have developed a distributed multi agent network, employing hybrid fuzzy reasoning for the real-time estimation of Ozone concentration. Aktan and Bayraktar, 2010 [START_REF] Aktan | The Neural Network Modeling of Suspended Particulate Matter with[END_REF] used ANNs in order to model the concentration of PM10. Hooyberghs et al., 2005 [9], propose ANN models as tools that forecast average daily PM10 values, in urban centers of Belgium, whereas Iliadis et al., 2007 [11], have done the same forecasting effort for O3 in Athens. A similar research is reported in the literature for Chile by Dı´az-Robles et al., 2009 [START_REF] Díaz-Robles | Seasonal Distribution and Modeling of Diesel Particulate Matter in the Southeast US[END_REF]. Thomas and Jacko, 2007 [START_REF] Theocharis | Fuzzy Systems Aristotle University of Thessaloniki[END_REF], have conducted a comparison between the application of Soft Computing and typical statistical regression in the case of air pollution. Finally, Mogireddy et al., 2011 [15] and Aceves-Fernandez et al., 2011 [START_REF] Aceves-Fernandez | Advances in Airborne Pollution Forecasting Using Soft Computing Techniques[END_REF], have used Support Vector Machines towards air pollution modeling.

Methodology

As it has already been declared, this paper presents a Soft Computing approach towards the assessment of air pollution levels in Cyprus, by introducing specific fuzzy sets. Soft Computing is an umbrella including neural networks, fuzzy logic, support vector machines and their hybrid approaches [START_REF] Kamataki | High scale transfer of Particulate Matter pollution in Thessaloniki[END_REF], [START_REF] Chaturvedi | Soft Computing Techniques and its Applications in Electrical Engineering Springer[END_REF]. Two types of exponential fuzzy membership functions and also S, Γ (Gama), Pi and Z FMFs were applied to determine the linguistics that characterize the severity of the problem in each case. It should be mentioned that this is the first time that such a wide range of FMFs are employed for the case of air pollution with actual field data obtained from urban centers.

Fuzzy membership functions

Fuzzy Logic (FL) is a universal approximator of real world situations. Several researchers use FL towards systems modeling [START_REF] Sumathi | Computational Intelligence Paradigms Theory and Applications using Matlab[END_REF]. The Z, S, Pi spline-based FMFs are named after their shape. They are given by the following functions 1 2 and 3 respectively. Function 4 stands for the Gama, denoted after the Greek letter Γ, where the exponentials Ex1 and Ex2 are given by functions 5 and 6.

(

) 1
(2)

(3) MATLAB has already built in code for the implementation of Z, S and Pi whereas the code for Γ and the two exponential functions have been developed in the form of ".m" executable files under the MATLAB platform. It must be clarified that in the case of the Z, S FMFs, parameters a and b locate the extremes of the sloped portion of the curve, whereas for the function Pi, a and d locate the "feet" of the curve and b and c locate its "shoulders" [START_REF] Olej | Modelling of Selected Areas of Sustainable Development by Artificial Intelligence and Soft Computing[END_REF]. Finally, in function 6 (Ex2) the parameters wleft (wl), cleft (Cl), cright Cr), wright (wr), must be positive numbers and their values must be chosen by the user, following the constraint that cl<cr Actual MATLAB code for the gamamf.m file:

            a X if a) - k(x 1 a) - k(x a X if 0 a) f(X, 2 2  (4)                          M X if e M X if e b) a, f(X, 2 2  b M X a X M   2 b a M   (5)                             case other any in 1 C X if e C X if e b) a, f(X,

function [ y ] = gamamf (x, params) % gamaMF(X, PARAMS) returns an array with the degrees of membership % for an input vector X % params=[X0 X1] is a vector with 2 elements determining the break points of the function if nargin ~= 2, error ('Two Parameters are required by gamaMF.'); elseif length(params) < 2, error ('gamaMF requires at least two parameters.'); end x0 = params(1); x1 = params(2); y = zeros(size(x)); % Creates table Y index1 = find(x <= x0); % If X is less than Xo or equal if ~isempty(index1), y(index1) = zeros(size(index1)); % τότε βάζει

0 end index2 = find(x > x0); % If X is greater than 31 if ~isempty(index2), y(index2) = (x1*(x(index2)-x0).^2)/(1+x1*(x(in- dex2)- x0).^2); end end 2

Data and Area of Research

This research effort presents the implementation of a soft computing system (SCS) that is based on fuzzy logic (FL). More specifically S, Γ, Pi and Z FMFs have been employed in order to determine the proper linguistic that corresponds to the levels of air pollution. The input data include 16,000 data vectors for the four main cities of Cyprus namely: Larnaka, Lemesos, Lefkosia (Nicosia) and Pafos. The field data are related to the period July 2006 to July 2008. Each record contains the following fields: Date and time, Time, Day, PM10 hourly concentrations (μg/m3), SEA (a binary index related to the seasonality of the case), DoW (direction of the wind), sin(HoD) and cos(HoD) (sine and cosine functions related to the effect of the hour of the day) [START_REF] Ziomas | A contribution to the study of photochemical smog in the Greater Athens area Beitr[END_REF] [21], PM10-24 (average PM10 related to 24 hours), T (Surface Temperature) and RH (relative humidity). The PM10 concentrations were measured by using the Tapered Element Oscillating Microbalance device and the Filter Dynamics Measurement system. In order to overcome the variations in the magnitude of the data, they were normalized (standardized to zero) by employing the following function 7:

    X Z (7)
where μ is the average value and σ is the standard deviation [START_REF] Dogra | Autoscaling" QSARword-A Stand Life Sciences Web Resource[END_REF].

The output of the developed FIS comprises of the fuzzy linguistic values Normal, Alert, Alarm which are related to the level of air pollution caused by PM10 and their assigned fuzzy membership values (FMV). European Union (EU) considers 50μg/m3 as the limit for the acceptable maximum daily concentration of PM10 whereas the maximum acceptable average annual boundary is 40μg/m3. Also EU has established the average daily values of 90 μg/m3 and 110 μg/m3as the Alert point and the Alarm limit respectively. The employment of specific numbers as the boundaries between Normal, Alert and Alarm are not rational especially when the measured values might not be very accurate. For example how can we accept the fact that 50μg/m3 are satisfactory for the concentration of PM10 whereas the 50.001 μg/m3 are not. On the other hand the main advantage of the fuzzy linguistic model introduced by this research is the fact that it is flexible and innovative, classifying the conditions of each case based on a real value (in the interval [0,1]) that specifies the degree of belonging to the proper linguistic [START_REF] Hooyberghs | A neural network forecast for daily average PM10 concentrations in Belgium[END_REF].

The minimum and maximum concentrations of the PM10 for the period 2006-2008 were input to the MATLAB fuzzy toolbox. Based on the range of these values, the parameters a, b for the Z and S functions and the actual values of the parameters a, b, c, d for the Pi FMF were determined automatically.

Results

The It is interesting to compare the classifications for two different cities for two different seasons (summer and winter).

An interesting finding is that in a period of 18 months, the Exponential2 function offers the highest number of Alarms in 10 cases (55.5%.) The exponential1 is second in the frequency of Alarms in 55.5% of the classificationς, whereas the Γ FMF is first in five cases (27.75%).

From table 4 it is concluded that the frequencies of the total hourly worst case situations in Larnaka are more or less the same for 2007 and 2008, regardless the FMF. It is obvious from the figures 1,2,3,4, that all of the functions except from the Gama are moving in a parallel mode. The Exp2 FMF always assigns the highest number of Alarms. However (with the exception of the Γ function) the frequency of the Alarms does not have big differences from one membership function to the other. Thus the Exp2 can be employed when the civil protection authorities wish to apply a quite strict policy. Otherwise the S or the Exp1 FMFs can offer a good alternative approach. Another finding is that the Γ function in most of the cases underestimates the risk and it offers rarely only a small number of Alarms. Only for the period October 2006 to January 2007 for Larnaka we have a peak in the number of Alarms introduced by the Γ FMF, which contradicts with the rest FMFs. Thus, the Gama function is not the proper one for this problem. The following table 5 presents the Alerts frequency distribution on a daily basis, for Larnaka, Lemesos, Lefkosia and Pafos for the period (July 2006 -July 2008). It is clearly shown that in Larnaka the highest total number of Alerts has been obtained for Monday followed by Friday and Tuesday. In Lemesos the corresponding ranking was Tuesday, followed by Monday and Friday. In Lefkosia, again the same days are taking the lead. Friday has the most total number of Alerts, followed by Tuesday and Monday. Finally in Pafos Monday is first, followed by Sunday and Friday whereas Tuesday is very close only with a difference of two cases. It is clearly shown that the three most risky days for all cities (with a small differentiation in the order) are Monday, Friday and Tuesday.

The following figure 7 provides clearly, additional arguments to support the conclusions discussed above. Again it is shown that Monday, Friday and Tuesday are the most risky days.

Fig. 7. Classification distribution in 3 classes for Larnaka

Also in figure 7 it is shown that in most of the cases, there is an "Alert situation" regardless the day of the week. Sunday and Saturday have the most Normal days, followed by Thursday.

Discussion -Conclusions

A first certain conclusion is that the situation in Cyprus regarding the PM10 concentration is becoming worse every year. A first glance at the graphs 1,2,3,4 reveals that the year 2008 is by far the worst compared to 2006 and 2007. Also it is obvious that there is a continuous and rapid increase of the problem which is detected by the huge differentiations between the peaks. The worst year with the highest number of Alarms is 2008 for Larnaka (150), Lemesos (160), Lefkosia (155). Only for Pafos May 2007 is the most risky with 120 Alarms but the peak of February 2008 is very close with 106. The most dangerous seasons are either October to December or February to April. Concluding it can be suggested that the problem of the particulate matter concentration in the urban centers of Cyprus is quite serious and the Alert cases are very common, whereas the Alarms are quite frequent. Also it has been shown that the problem is seasonal and the day or the month, play a very serious role. This of course is due to human activities or weather conditions. The S function is a little bit more optimistic, giving the least number of Alarms, whereas the Exp2 FMF is the most strict one.

The Gama function has a very low estimation of the risk (the problem is underestimated significantly) and it is differentiated from all other FMFs that have very similar behavior.

Future research will be the conversion of the CIS to a real time one. Working in a real time mode and offering real time classifications, it can enable the effective handling by the local authorities.

Fig. 1 .Fig. 2 .Fig. 3 .

 123 Fig. 1. Evolution of Alarm Signals for Larnaka with various FMFs

Fig. 4 .

 4 Fig. 4. Evolution of Alarm Signals for Pafos with various FMFs

Fig. 5 .

 5 Fig. 5. Classification in 3 classes for Larnaka (December 06-February 07)

Fig. 6 .

 6 Fig. 6. Classification in 3 classes for Lemesos (December 06-February 07)

Table 1 .

 1 following table 1 is a small sample of the hourly classification performed for Lemesos Cyprus, on the 10th of July 2006 based on the PM10 concentrations. It is interesting that there is a continuous Alert situation after eight o'clock in the morning and at 12 o'clock there is an Alarm signal. The situation goes back to Normal after 18:00 whereas there is a continuous Alert situation in the mean time. A classification for Lefkosia on the 12th of October 2006 reveals two Alarm situations, one at 7:00 in the morning and one at 18:00 in the afternoon. Pafos has also been assigned Alert Linguistic from 9:00 in the morning till 17:00 and also two Alarm signals from 18:00 till 19:00 for the 13th of August 2006. Sample of hourly classification for the PM10 (Lemesos July 06)

			Degrees of Membership to the
	City of Lemesos	Pollutant	three Linguistics
	Date-Time	PM10	Normal Z-FMF	Alert Pi-FMF	Alarm S-FMF	Corre-sponding Linguistic
	10/7/2006 1:00	8.56	0.98	0.00	0.00	Normal
	10/7/2006 2:00	47.05	0.34	0.01	0.00	Normal
	10/7/2006 3:00	9.50	0.97	0.00	0.00	Normal
	10/7/2006 4:00	45.22	0.38	0.00	0.00	Normal
	10/7/2006 5:00	79.53	0.00	1.00	0.00	Alert
	10/7/2006 6:00	98.71	0.00	0.91	0.04	Alert
	10/7/2006 7:00	25.84	0.79	0.00	0.00	Normal
	10/7/2006 8:00	90.51	0.00	1.00	0.00	Alert
	10/7/2006 9:00	82.28	0.00	1.00	0.00	Alert
	10/7/2006 10:00	76.54	0.00	0.98	0.00	Alert
	10/7/2006 11:00	68.71	0.04	0.79	0.00	Alert
	10/7/2006 12:00	133.82	0.00	0.00	0.85	Alarm

Table 2 .

 2 Alarm cases for a period of 12 months in Larnaka

	Month 2007	S	Γ	Exp1	Exp2	Month 2007	S	Γ	Exp1	Exp2
	Jan	4	7	11	12	July	24	4	36	42
	Febr	18	13	24	27	August	19	20	17	19
	March	15	30	19	21	Sept	30	12	46	50
	April	15	49	23	24	Oct	90	64	116	124
	May	27	36	85	89	Nov	59	29	81	90

Table 3 .

 3 Alarm cases for 6 months of 2006 in Larnaka

	Month 2006	S	Γ	Exp1	Exp2
	July	7	12	13	14
	August	10	10	22	23
	Sept	29	11	38	40
	Oct	9	34	13	13
	Nov	3	58	5	6
	Dec	11	30	14	14

Table 4 .

 4 Aggregation of the hourly Alarm situations in Larnaka for two years

	Year	Number of Alarms (S)	Number of Alarms (Γ)	Number of Alarms (Exp1)	Number of Alarms (Exp2)
	2007	381	337	512	556
	2008	388	480	452	476


Paris Giampouras
email: parisg@iit.demokritos.gr

Eleni Charou
email: exarou@iit.demokritos.gr

Anastasios Kesidis
email: akesidis@teiath.gr

Artificial Neural Network Approach for Land Cover Classification of Fused Hyperspectral and Lidar Data

Keywords: Hyperspectral images, LIDAR, land cover classification, neural networks, principal component analysis

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

Introduction

Operational monitoring of land cover/ land use changes using remote sensing is of great importance for environmental Remote sensing due to its repetitive nature and large coverage is a very useful technology to perform such kind of study. This technology, if properly integrated with automatic processing techniques, allows the analysis of large areas in a fast and accurate way. Several studies have been carried out in this field, analyzing the potentialities of different remote sensing sensors such us Passive Multispectral (3-10 spectral bands) or Hyperspectral(several 100s spectral bands). The abundance of spectral information in the hyperspectral image has the potential to differentiate land cover classes with similar spectral characteristics that cannot be distinguished with multispectral sensors. Active LIDAR remote sensing sensors are increasingly used in the context of classification and constitute a valuable source of information related to the altitude. Thus hyperspectral and LIDAR data could be used complementary, as they contain very different information: hyperspectral images provide a detailed description of the spectral signatures of classes but no information on the height of ground covers, whereas LIDAR data give detailed information about the height but no information on the spectral signatures [START_REF] Dalponte | Fusion of Hyperspectral and LIDAR Remote Sensing Data for Classification of Complex Forest Areas[END_REF]. In this study LIDAR and hyperspectral images are integrated for the land cover classification. To show the usefulness and complementarity of LIDAR and hyperspectral image, a land cover classification was performed using hyperspectral image alone. This paper is organized into 4 sections. Section 2 presents the methodology used, the main preprocessing techniques adopted and describes the data set used in our analysis. Section 3 describes and discusses the experimental results obtained. Finally, Section 4 draws the conclusion of this paper.

Methodology and Data

Hyperspectral data undoubtedly possess a rich amount of information. Nevertheless, redundancy in information among the bands opens an area for research to explore the optimal selection of bands for analysis. Theoretically, using images with more bands should increase automatic classification accuracy. However, this is not always the case. As the dimensionality of the feature space increases subject to the number of bands, the number of training samples needed for image classification has to increase too. If training samples are insufficient then parameter estimation becomes inaccurate. The classification accuracy first grows and then declines as the number of spectral bands increases, which is often referred to as the Hughes phenomenon [START_REF] Hughes | On the mean accuracy of statistical pattern recognizers[END_REF]. In the proposed method, hyperspectral image data are fused with LIDAR data in order to perform land cover classification. Principal Component Analysis is applied on the Hyperspectral image to perform feature extraction and dimension reduction while preserving information. The first four principal components along with the LIDAR image are used for classification by training a supervised feed-forward neural network. The following sections describe in detail the several steps of the method.

Principal Component Analysis

Classification performance depends on four factors: class separability, training sample size, dimensionality, and classifier type [START_REF] Hsien | Classification of High Dimensional Data[END_REF]. Dimensionality reduction can be achieved in two different ways. The first approach is to select a small subset of features which could contribute to class separability or classification criteria. This dimensionality reduction process is referred to as feature selection or band selection. The other approach is to use all the data from original feature space and map [START_REF] Petridis | Non redundant feature selection of multiband remotely sensed images for land cover classification[END_REF] the effective features and useful information to a lower-dimensional subspace. This method is referred to as feature extraction. The Principal Component Analysis PCA is a well known feature extraction method in which original data is transformed into a new set of data which may better capture the essential information. When variables are highly correlated the information contained in one variable is largely a duplication of the information contained in another variable. Instead of throwing away the redundant data principal components analysis condenses the information in intercorrelated variables into a few variables, called principal components.PCA analysis have been succesfully used in Hyperspectral data classification [START_REF] Rodarmel | Principal Component Analysis for Hyperspectral Image Classification[END_REF].

Neural Networks

The use of Artificial Neural Networks(ANNs) for complex classification tasks of high dimensional data sets, such as hyperspectral images, has been widely spread in the last years. Several studies dealing with pattern recognition/classification problems of remote sensing data, [START_REF] Mernyi | Classification of hyperspectral imagery with neural networks: Comparison to conventional tools[END_REF][START_REF] Mernyi | Quantitative comparison of neural network and conventional classifiers for hyperspectral imagery[END_REF] have shown that ANNs, in most cases, achieve better results in comparison to conventional classifiers.

Their non-linear properties and the fact that they make no assumption about the distribution of the data, are among the key factors of the NNs classification power. Neurons with nonlinear activation functions are arranged in layers and act like a set of piece-wise nonlinear simulators [START_REF] Hornik | Multilayer feedforward networks are universal approximators[END_REF][START_REF] Haykin | Neural Networks: A comprehensive foundation[END_REF]. Neural networks are able to learn from existing examples adaptively, thus, the classification is made objective [START_REF] Beale | Neural network toolbox[END_REF].

Data Description

The data used in this study is obtained from the data fusion contest 2013, organized by the Data Fusion Technical Committee of the IEEE Geoscience and Remote Sensing Society (GRSS). The current contest involves two sets of data a hyperspectral image (Fig. 1) and a LIDAR derived Digital Surface Model (DSM) (Fig. 2), co-registered and both at the same spatial resolution (2.5 m). The size of the bands of the hyperspectral image as well as the LIDAR is 349x1905 pixels. They were acquired over the University of Houston campus and the neighboring urban area. For the current data set, a total of 144 spectral bands were acquired in the 380 nm to 1050 nm region of the electromagnetic spectrum. The goal is to distinguish among the 15 pre-defined classes. The labels as well as a training set for the classes are also provided (Table 1).

Results and Discussion

For the purpose of this study the MATLAB software is used. The Principal Component Analysis is applied on the hyperspectral image. The first four PCA components i.e PCA1,PCA2,PCA3,PCA4 which convey the 99.81% of the information along with the LIDAR opted as our dataset for the processing that follows. A three layer feed-forward ANN is implemented. The input layer of the ANN consists of 5 neurons : 4 neurons for PCA1, PCA2, PCA3, PCA4 and one neuron for the LIDAR image. The hidden layer is composed of 120 neurons and the tan-sigmoid is selected as the layer's transfer function. The output layer comprised of 15 nodes equal to the total number of the classes. The linear function is opted as the output's layer transfer function. The ANN is trained by the set of 2832 samples of the Table 1. The training set is divided randomly into three sets, namely, the training, validation and test set, respectively. About 70% of the total samples is used as the training set of the ANN. Another 15% is used for validation while the rest 15% is dedicated to testing purposes. The ANN is trained using the Bayesian Regularization back-propagation algorithm [6]. In this case, the weights and bias values are updated according to Levenberg-Marquardt optimization. This minimizes a combination of squared errors and weights, and then determines the correct combination so as to produce a network that generalizes well. After 552 epochs the training procedure is stopped. The test set success is 94.6% , as it can be seen in detail in the confusion matrix of (Fig. 3). The performance achieved, is higher than 95% in the majority of the classes. Specifically, in 7 out of 15 classes (grass healthy, grass stressed, grass synthetic, tree, soil, water, running track), a 100% success is achieved. For 5 classes (commercial, highway, railway, parking lot 1, tennis court) the performance achieved lies between 95% and 99.5%. The classes "residential" and "road" present 85%-90% rate of success. The lowest value (61.5%) is noticed for class parking lot 2 mostly due to the high correlation and the low separability between this class and the parking lot 1 class. By applying the ANN on the whole dataset, we get the resulting image that can be seen in Fig. 4, where each class is depicted with a different color. A quantitative assessment on the whole image, is not possible since no ground truth data are provided. However, a qualitative assessment on the whole classified image reveals promising results. It can be noticed that most pixels which belong to classes where high success rates are achieved, are correctly classified (compared to the RGB image of Fig. 2). In contrast, poorer results are achieved for pixels in classes characterized by lower classification rates, such as "parking lot 2".

Conclusion

A fully automated process based on hyperspectral and LIDAR data for efficient land cover classification is presented. The fusion of hyperspectral image and LI-DAR data is shown that can be used complementary, for effective land cover classification based on ANNs. Even in highly correlated classes such as grass healthy, grass stressed (unhealthy) and grass synthetic (ANN's) performance is very satisfactory. The methodology presented can also be used in other classification tasks.

Fig. 1 .

 1 Fig. 1. RGB combination of hyperspectral image of the study area

Fig. 2 .

 2 Fig. 2. LIDAR image of the study area

Fig. 3 .

 3 Fig. 3. Test Set Confusion Matrix

Fig. 4 .

 4 Fig. 4. Resulting Image

Table 1 .

 1 Distribution of training sample among investigated classes

	Class Index Class Name Training Samples Number
	1	Grass Healthy	198
	2	Grass Stressed	190
	3	Grass Synthetic	192
	4	Tree	188
	5	Soil	186
	6	Water	182
	7	Residential	196
	8	Commercial	191
	9	Road	193
	10	Highway	191
	11	Railway	191
	12	Parking lot 1	192
	13	Parking lot 2	184
	14	Tennis Court	181
	15	Running Track	187

ACKNOWLEDGEMENTS : This research has been co-funded by the European Union (European Social Fund) and Greek national resources under the framework of the Archimedes III: Funding of Research Groups in T.E.I. of Athens project of the Education & Lifelong Learning Operational Programme. The authors would also like to acknowledge the Data FusionContest 2013 Technical Committee of the IEEE Geoscience and Remote Sensing Society (GRSS) for providing the dataset.


David Palma
email: palma@onesource.pt

Joao Goncalves

Luis Cordeiro
email: cordeiro@onesource.pt

Paulo Simoes
email: psimoes@dei.uc.pt

Edmundo Monteiro
email: edmundo@dei.uc.pt

Panagis Magdalinos
email: panagis@di.uoa.gr

Ioannis Chochliouros
email: a.ichochliouros@oteresearch.gr

Tutamen: An Integrated Personal Mobile and Adaptable Video Platform for Health and Protection

Keywords: HD video, Streaming, Smart Cities, Mobile First Responders

A framework for mobile and portable High-Definition Video streaming is proposed, developed and assessed. Suitable for emergency scenarios, involving for instance ambulances and fire-fighters, the presented framework resorts to a state-of-art platform which considers offthe-shelf hardware and available video codecs for High-Definition Video. The obtained results show that the proposed architecture is able to efficiently support rescuing teams in the demanding scenarios where they operate, guaranteeing video quality and ease of use. This solution is particularly useful for situations where experts in the fields can accurately provide their insights and contributions remotely and in a timely fashion.

Introduction

Everyday advances in technology and its availability within an increasing number of communities has motivated new approaches towards technological innovation in many sectors. A valuable contribution in this aspect is the definition of Smart Cities, where technologies can be used to provide dynamic and adaptive services and contexts. Among several topics, the LiveCity project, in which this work has been developed, is concerned with sustainability as well as with a reliable, smart and secure cities. By exploring the advances in wireless communications, in conjunction with the portability of increasingly more powerful computers, this work aims at extending the benefits of integrated personal mobility for demanding scenarios involving aspects such as healthcare and civil protection.

Previous works have already proposed many end-to-end mechanisms connecting hospital experts with ambulances and similar agents in emergency scenarios.

For instance, not only simulation based but also real-time non-diagnostic systems have been developed, capable of providing trauma and echo-cardiogram videos [START_REF] Panayides | An overview of recent end-to-end wireless medical video telemedicine systems using 3g[END_REF]. Nonetheless, these solutions are strongly dependent on the entire infrastructure provided by ambulances, being limited in terms of their operational area, requiring patients to be inside the vehicle. Moreover, the addition of features such as the monitoring of other vital signals, a clear image of the patients' face or any non-digital medical equipment is non-trivial in these solutions.

Nowadays a big challenge is the design of mobile and ubiquitous telemedicine, versus the known store and forward telemedicine which typically demands tightlycoupled services and rigid architectures [START_REF] El Khaddar | Emerging wireless technologies in e-health trends, challenges, and framework design issues[END_REF]. The Tutamen proposal, takes its name from the same latin word which stands for protection, defence and caring. It tackles flaws such as lack of real-time communication between rescuing teams, the portability and flexibility that will allow its usage in a seamless and effective manner, defining a new perspective towards the exploitation of technology for effectively improving the quality of living both in urban and remote areas. Moreover, this proposal is expected not only to allow a physician to be available anywhere at anytime, but also to follow a well defined methodology with field trials and real feedback from the involved professionals, which are typical disregarded by other solutions.

Other recent solutions, such as the eBag [START_REF] Sugita | Telemedicine system necessary in disaster areas[END_REF], require teams operating in the field to carry a suitcase equipped with a full-size laptop and other equipment. This not only creates difficulties in transportation but also in setup. When responding to an emergency scenario, timing is critical and other similar solutions such as the use of robotic agents [START_REF] Kumar | [END_REF], makes the operation more cumbersome, possibility creating trust issues with patients regarding their efficacy.

The technological challenges raised by the need of providing an ubiquitous and real-time high definition (HD) stream have been addressed in three different approaches, guaranteeing that a modular solution would be achieved. By separating the proposed Tutamen architecture into three blocks -video acquisition, streaming and interfacing -the personal video-to-video (v2v) system was designed taking into account the possibility of future hardware and software updates.

This work presents the Tutamen framework, concerning both wearable and flexible hardware and the software mechanisms used for adaptable real-time video streaming, taking into account the available network conditions.

A general description of the LiveCity project in which the mobile video platform has been developed is presented in Section 2, followed by a detailed presentation of the proposed solution in Section 3, considering a preliminary use case for ambulances, requirements and methodology in Section 4. The assessment of the performance and main characteristics of the Tutamen personal unit are included in Section 5. Finally, Section 6 highlights the main contributions provided by this work.

Empowering inhabitants of a city by providing them means to interact with each other in a farther prolific, effectual and socially useful way, by the use of high quality v2v over the Internet, could be presented as the main goal of LiveCity Project. The proposed augmentation could be used to save patients lives, improve city administration, reduce fuel costs, reduce carbon footprint, enhance education and improve city experiences for tourists and cultural consumers.

LiveCity promotes the context of a modern world where live HD interactive v2v can be easily available on a variety of display devices and where a video call with HD quality can be as globally reachable to a city environment as a plain old telephony call; or even a world where any video screen coupled with a video camera in a city could connect an HD full screen video call (where HD video represents moving pictures with at least a resolution similar to 1280 pixels wide and 720 pixels height) at an attractive cost with seamless, utterly simple usability. This is the vision of the essential LiveCity approach. To realize its strategic aims, LiveCity considers standard video encoding already available in off-the-shelf devices.

The LiveCity effort aims to fill the above matters, per separate option, by providing appropriate responses and by suitably promoting experiences and results gained from pilot actions.

Camera Data Acquisition Prototype

Initially developed for emergency first responders -namely paramedics units deployed in emergency ambulances -so as to provide a balanced compromise between computational resources (necessary to acquire, encode and transmit live HD video), mobility (wearable device, battery autonomy and hands-free operation) and good performance under extreme conditions, mostly due to the inclusion of rugged devices, video camera able to self-adjust to variable lighting environments and to the possibility of integration with emergency responders equipment, as shown in Figure 1. The system, with its core component depicted in Figure 2, supports any type of Global System for Mobile Communications (GSM) or Long Term Evolution (LTE) based networks by the means of a Universal Serial Bus (USB) dongle. Composing the system is an x86 compliant dual core board, coupled with an High-Definition Multimedia Interface (HDMI) Mini Card capture device which interfaces with a Mini Peripheral Component Interconnect (PCI) Express expansion card needed by the main board to support this kind of device. External to the main component, we have buttons connected to the machine, allowing the user to control and change states of the current call. Travelling through the back of the user, is a sleeve with cabling to connect the external camera and headset, providing the user with audio feedback and the hospital with a realtime video and audio feed. This setup has been developed within the LiveCity project and its performance results for v2v communication are presented in this paper.

Use Case -Ambulances

During the so called "golden hour", patients suffering from an heart attack, on the verge of having a stroke, or suffering from some type of environment induced trauma, could significantly benefit from speed about decision making.

Early recognition of stroke features and opportune referral to a stroke unit by the means of v2v enabled technology should improve overall outcome, saving lives and improving the patient chance of independently functioning, as well as an expedited advice concerning optimal pain management and requirement of evacuation on trauma victims.

Requirements and Methodology

The most important step in the design and implementation of the prototype was the extraction of a detailed list of requirements from the involved user groups. Due to the focus of the application, this effort was of paramount importance and had to be designed and implemented in every possible detail. Most of these requirements were assessed by working closely with emergency personnel from several different areas, but mostly, first responders.

From a methodological point view we applied an iterative and incremental process (closely resembling the concept of Rational Unified Process [START_REF] Kruchten | The Rational Unified Process: An Introduction[END_REF]) imple-mented through consecutive cycles of interviews and subsequent software releases. The latter facilitated timely feedback from the involved user groups while in parallel assured that the development process will not result in an application which although functional is useless to the end user.

In the context of this paragraph we will try to briefly present this process focusing primarily in end user requirements, how they were captured and what they implied for the subsequent design and implementation process. The end product is a v2v software application with an end user interface which offers the doctor an opportunity to intervene early in emergency situations and offers the paramedic the opportunity to get medical assistance in a difficult situation.

We look at the three use case scenarios of heart attack, stroke and trauma together for the purposes of the hardware and software development. The storyboard for the emergency use case is the following:

-The paramedic initiates a video-call to the hospital using a portable device.

-In case the doctor is directly available, an alert is sent to his smart phone.

-The doctor proceeds to the emergency room and answers the call.

-The paramedic speaks into the microphone held on his headband and explains the issue. -The doctor looks at the patient via the monitor and instructs the paramedic to focus on the part of the patient of interest. -The doctor asks questions to the patient in order to assess his condition.

-The doctor instructs the paramedics on how to proceed.

The latter provided the first basis for design of the application. However, more user specific requirements came after the first release of the application. The involved user groups have different requirements; paramedics need a simple application with a maximum number of two or three buttons that will enable them to communicate with the hospital with minimal overhead; on the other hand the doctors required an application that supports full management of the incoming video and audio streams. Thus, following the well known Model-View-Controller software design concept, two different flavours for the end user application were designed.

From the hospital perspective, the application caters for stream management (video and audio stream management), notifications to the end user (SMS texting in case of absence, highlight of emergency call), capturing of still images from the video source, manual and/or dynamic adaptation of the video/audio quality and encrypted storage of patient information. Finally, the doctor can initiate a call to an ambulance; however the latter is permitted if and only if a call has been received by that ambulance. Figure 3 provides the layout.

From the paramedics' point of view, the application should be simple and easy to use with a minimum number of buttons facilitating communication with the hospital. All notifications and interruptions should take place through a simple beep-code thus enabling the ambulance crew to minimize the amount of time being distracted because of the application.

Not only the application has gone through the scrutiny of the paramedics', but also the hardware configuration of the whole platform. Targeted at personnel with different requirements, one of the most requested features was modularity. Being able to switch the position of the computer box and how the cabling flows through the belt and hoses, became mandatory.

Main Results

Aiming to provide a proper evaluation of the platform, measurements regarding the overall performance of the platform during the process of video acquisition, processing and transmission will be performed. Two different types of measurements will be made; firstly the resulting Peak Signal-to-Noise Ratio (PSNR) of the codec while encoding the acquired video into the different bit rates and resolutions shall be measured; secondly a measurement of the transmitted video's PSNR, using different bit rates and resolutions, will be obtained as well. For the sake of simplicity, only the performance of one video codec will be reviewed and the choice will fall upon the open implementation of the H.264/MPEG-4 AVC video codec, x264, since it is the considered to be very robust for video streaming in wireless networks [START_REF] Wang | RTP Payload Format for H.264 Video[END_REF].

In order to measure the encoding performance of the codec, its internal measuring tool will be used to retrieve the global PSNR, but with the caveat of not enabling its optimizations for PSNR monitoring. The reason behind this decision has to do with the fact that it is intentional to measure the codec performance with the optimizations that were selected for the Tutamen live streaming, and not the optimizations that achieve a most advantageous PSNR during the encoding process.

An additional quality metric that is typically considered is the Mean Opinion Score (MOS) which indicates the quality of a video and is quantified from 1 (bad quality) up to 5 (excellent quality). However, this metric is a sensorial metric, which means it depends how the quality perceived by humans, therefore not necessarily providing accurate results when calculated [START_REF] Bernardo | Voip over wimax: Quality of experience evaluation[END_REF].

The video quality assessment will be performed taking into account the degradation introduced both by the transcoding and streaming processes. For comparison purposes, the raw FullHD video will be considered as a reference value and compared against the transcoded videos at different bit-rates prior to and after streaming. In fact, variable bit-rates will be used during the streaming of the video, adapting to the available network conditions. However, the reduction of the videos' bit-rate will lower the initial PSNR, therefore the bit-rate reduction must be sensible. In order to measure the PSNR resulting from the transcoding and streaming process, the Evalvid tool [START_REF] Klaue | Evalvid -a framework for video transmission and quality evaluation[END_REF] and its known methods will be used.

Usability / Wearable Characteristics

Bearing in mind the use cases proposed for the Tutamen platform, its usability and overall look and feel experience is of paramount importance. In fact, the definition of a comfortable and intuitive device for either physicians, fireman or any other unit working under emergency situations, has influenced not only the design of the wearable communication unit but also of its mechanisms and interaction procedures with the remote units in control centres. Therefore, the results obtained from the process of creating the hardware-based interface and the communication module, provide important insights for future related works.

The developed work was closely followed by doctors and physicians which provided their contribute and knowledge regarding the main requirements and challenges in emergency situations. A key point was the ease in using the entire platform, not only should the device be easily carried, being light in both weight and size, but it should also be intuitively operated, requiring as few buttons as possible. These requirements resulted in a solution slightly exceeding 1kg that can be used by fitting an adjustable belt, capable of being worn with any uniform in any atmospheric conditions. Moreover, taking into account the ease of operation, a simple three button system was developed.

With the available buttons, the units carrying the Tutamen device are able to start and stop the entire system by using the power button as well as to start and stop a direct call to the control centre or hospital. Moreover, since some disaster scenarios lack the desirable lighting, the third button can be used to enable a powerful lighting system, capable of providing good quality video. Finally, due to the harsh conditions in which emergency units usually operate, the buttons module is protected with a cover and each operation (i.e. button press), requires a button press of at least two seconds, thus avoiding accidental operations.

An important requirement identified during the development of this work, in conjunction with emergency teams, was that the equipment should be as handsfree as possible. Therefore, the video acquisition unit, as well as the audio and lighting systems, have considered taking into account this aspect. Regarding the video and lighting systems, they have been designed so that both can be attached to a working helmet or to a headband, allowing the individual wearing the device to transmit and illuminate the desired regions of interest without any adjustments or configurations. Additionally, in order not to distract the person operating Tutamen, each action in the system is transmitted through a headset that is also used to transmit audio to the control centre.

Technical Performance

In order to correctly address the difficulties found by the operating teams in the field, the performance of the used hardware has been taken into consideration, influencing the choices for each component included in the equipment. The used camera is able to provide FullHD Video at several frame rates, guaranteeing a 170°field of view through a wide angle lens, for up to 2.5 hours of continuous video. The camera has a dedicated power source which can easily be replaced or recharged.

Coupled with the camera acquisition unit, a supportive light system has been developed, providing a 52 Lumen output with a wide viewing angle as well. The lighting system not only has a small power consumption (1.1 Watt), which increases the total working time of the Tutamen solution, but also it is able to operate for 50,000 hours without having to be replaced.

Regarding the overall system's autonomy, the used batteries are able to support the platform up to 3 hours in full load, offering the possibility of being replaced by other charged batteries while the empty batteries can be recharged in a separate module. The running time of the system can be vastly extended if the calls to the coordination centre are only periodic. Moreover, the system can be easily shut-down and booted into working mode in a matter of seconds. Considering the audio system, which will provide most of the feedback to the physician, a single-sided ear coupling Sennheiser headset is used for system related events (i.e. warnings and notifications such as system ready, new call arrived, among others), while at the same time it is also used for the communication between the physician and the control centre. The headset includes also an adjustable microphone, a button to mute the microphone and a volume regulator for a better experience.

Calling Performance

The establishment of call between the field teams and the control centres involves the transmission of both audio and FullHD video. Since audio over the internet has already been widely studied, the call performance analysis will focus on the challenges posed by the transmission of high-definition video. Taking into account the variable and limited bandwidth of 3G Networks, different tests were performed with different encoding bit-rates of the video codec, reflecting the available bandwidth at a given time. This feature of the Tutamen architecture aims at guaranteeing the best possible quality at any given time.

Generally, when connecting to a 3G Wireless Network, the device knows the available bandwidth. However, the announced bandwidth does not always correspond to the real available bandwidth, for instance, while the High-Speed Downlink Packet Access (HSDPA) standard may announce 7.2Mb/s bandwidth, this value only represents the maximum bandwidth than can be achieved, providing no actual guarantees. The presented results show the quality of different bit-rate videos, transmitted through the same network conditions of 7.2Mb/s of bandwidth. Since many interferences may occur, the desired transmission bitrate should be bellow the maximum available bandwidth.

The transcoding process at lower bit-rates may reduce the overall quality of the video. However, the results we present in this paper show that less harmful to previously adapt the video quality to the available network conditions, rather than maintaining a higher quality and incur packet losses that may carry key frames. In fact, the resulting degradation of a higher bit-rate video being transmitted over a lower bandwidth network, may be higher than the the degradation of a video previously transcoded with a lower bit-rate, thus with a forced reduction of the video quality before being streamed, which during the streaming process has few or no losses that compromise the video integrity.

Table 1 presents the percentage of degradation obtained for different bitrate videos, considering the same network conditions. This illustrates the need to correctly adapt videos' bit-rates during the transcoding process, guaranteeing that the number of losses is reduced and that overall perceived quality is the best possible. In particular, by analysing the results in this figure, it becomes clear that bit-rates higher or closer to the network's maximum bandwidth, despite having a lower degradation during the transcoding process, register a higher degradation after being streamed. On the other hand, moderate adjustments of bit-rate are able to provide a better quality after being streamed, presenting a lower degradation. Nonetheless, as previously mentioned, the sent videos' bit-rate must be enough such that it does not affect the original quality significantly. For example, for a 2Mb/s bit rate, it is clear in Table 1 that even though the lower bit-rate video is within the limits of the network, with few packet losses, it has an initially higher degradation than for 5.5Mb/s, not being worth the using a lower bit rate.

An interesting result occurred for the 384kb/s bit rate as despite having a higher transcoding degradation, there were no registered packet losses. The overall quality is a result of the x264 codec which is able to maintain an acceptable quality regarding the measured PSNR, suggesting that other measurement mechanisms should be used with this codec.

Conclusions

The constant development of lighter and more powerful hardware has motivated the creation of new approaches for improving citizens life quality. The work presented in this paper introduces a portable platform for high quality video transmission in emergency scenarios. By resorting to state-of-the-art hardware and video codecs, 3G networks are used to guarantee the expertise of highly qualified professionals in remote locations in timely matter.

Resulting from the feedback obtained from different emergency teams, the designed equipment and architecture stand-out by being extremely portable and simple to use, while allowing High-definition Video to be seamlessly transmitted between teams in the field and experts in the control centre.

In order to assess the quality provided by the Tutamen platform, comprehensive video tests were performed, evaluating the quality of the transmitted videos with different bit-rates in different network conditions. The perceived video quality is of paramount importance as it will be the main input source at the control centre. The obtained results revealed that the platform is capable of successfully encoding and transmitting HD Video with a good MOS (higher than 4), adapting to different network conditions.

An important contribution from the developed work concerns the integration of off-the-shelf hardware with the defined software platform, guaranteeing real-time adaptable video transmission that guarantees the best possible video quality.

Future work involves the extension of this platform to other services such as security and education. Moreover, in order to further improve the adaptable characteristics of the presented solution, an additional feature would be the reduction of the video's resolution when FullHD is not mandatory or whenever network conditions are very poor.

Fig. 1 .

 1 Fig. 1. Equipped Member

Fig. 2 .Fig. 3 .

 23 Fig. 2. Micro Computer

Table 1 .

 1 Degradation Comparison over a network of 7.2 Mbps

	Bit Rates	% of Degradation
	Mb/s Transcoding Streaming Overall
	12.0	2.17	33.65	35.09
	7.2	4.64	22.47	26.06
	5.5	6.02	18.45	23.36
	2.0	11.08	16.61	25.85
	.384	18.37	0.00	18.37

Acknowledgements

This work was performed in project LiveCity which has received research funding from the Community's Seventh Framework programme. This paper reflects only the authors' views and the Community is not liable for any use that may be made of the information contained therein. The contributions of colleagues from LiveCity consortium are hereby acknowledged.


Andreea Molnar
email: andreea.molnar@brunel.ac.uk

Vishanth Weerakkody
email: vishanth.weerakkody@brunel.ac.uk

Defining Key Performance Indicators for Evaluating the Use of High Definition Video-to-Video Services in eHealth

Keywords: high definition video, eHealth, tele-monitoring, glaucoma, KPIs

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

Introduction

In the current economic climate, where governments are under constant pressure to deliver 'better for less', the role and impact that Information and Communication Technology (ICT) has on core public services such as healthcare has increased more than ever before. In particular, most European governments see ICT as a means to facilitate and improve health services and as a mechanism to reduce the cost associated with healthcare service delivery [START_REF] Charles | Telemedicine can Lower Costs and Improve Access[END_REF][START_REF] Dorsey | Randomized Controlled Clinical Trial of "Virtual House Calls" for Parkinson Disease "Virtual House Calls" for Parkinson Disease[END_REF][START_REF] Porter | Redefining Health Care: Creating Value-based Competition on Results[END_REF][START_REF] Stefanou | ERP Integration in a Healthcare Environment: A Case Study[END_REF]. Among the variety of existing health services, in this paper, we focus on tele-monitoring and we argue that it is possible to improve the quality and acceptance of existing tele-monitoring services by using HD V2V communication. This research is performed in the context of the LiveCity project (EU FP7 CIP grant agreement No. 297291), and focuses on the case of tele monitoring for glaucoma patients.

Although tele-monitoring is not necessarily a new concept, problems are reported due to image noise and jerky sound that may be crucial for the proper diagnosis of patients [START_REF] Shimizu | High-Quality Telemedicine using Digital Video Transport System over Global Research and Education Network[END_REF]. In this context, the LiveCity project aims to ensure that HD V2V communication is provided between the hospital and the patient. This is of particular importance for the LiveCity case study, as it involves communication with glaucoma patients, and in this case, for a consultation, high quality images are imperative [START_REF] Stamatelatos | Video-to-Video for e-Health: Use Case, Concepts and Pilot Plan[END_REF].

However, the technical details on providing high quality video are out of the scope of this paper, as this paper focuses on the evaluation of tele-monitoring services through V2V by defining a set of KPIs.

In order to do so, the paper is structured as follows: The next section sets the background of this research. It is followed by a brief introduction on how delivery of HD V2V services can be facilitated over public infrastructure. The next section then briefly introduces the evaluation phases of the LiveCity project, followed by an initial set of KPIs for eHealth services. This is followed by the main results of a semi-structured interview that was conducted to collect data from a doctor treating glaucoma patients. The paper then concludes by offering a discussion of the results, conclusions and future work.

Background

Using ICT in health services (electronic health -eHealth) has been seen as a solution for reducing the cost associated with healthcare delivery [START_REF] Dorsey | Randomized Controlled Clinical Trial of "Virtual House Calls" for Parkinson Disease "Virtual House Calls" for Parkinson Disease[END_REF], improving decision making to increase the quality of service offered to patients, improving the access to information [START_REF] Lenz | Towards a Continuous Evolution and Adaptation of Information Systems in Healthcare[END_REF], and contributing to the saving of lives through advanced tools and techniques [START_REF] Haughom | Implementation of an Electronic Health Record[END_REF]. However, the adoption of ICT in healthcare has not met initial expectations with reports of poor take up by both practitioners and patients [START_REF] Atherton | An Information Revolution: Time for the NHS to Step up to the Challenge[END_REF][START_REF] Cresswell | The NHS Care Record Service (NHS CRS): Recommendations from the Literature on Successful Implementation and Adoption[END_REF]. Prior research has identified several issues with the current use of e-Health such as the communication infrastructure [START_REF] Charles | Telemedicine can Lower Costs and Improve Access[END_REF][START_REF] Cresswell | The NHS Care Record Service (NHS CRS): Recommendations from the Literature on Successful Implementation and Adoption[END_REF], the necessity for the system to be user centric [START_REF] Westrup | What's in Information Technology[END_REF], and the need to involve stakeholders from the initial stages of service design [START_REF] Charles | Telemedicine can Lower Costs and Improve Access[END_REF]. Several services that have been used in e-health, such as Electronic Health Records (EHRs) [START_REF] Currie | Evaluating the Governance Structure for Public Sector IT: The UK National Programme in the Health Service[END_REF][START_REF] Lafky | Information Systems and Health Care X: A User Driven Approach to Personal Health Records[END_REF], picture archiving and communication system, and tele-medicine [START_REF] Menachemi | Factors Affecting the Adoption of Telemedicine-A Multiple Adopter Perspective[END_REF] as core services that are enabled by ICT. This research focuses on a particular type of tele-medicine/tele-monitoring, and explores the use of HD V2V between the patient and the hospital. Tele-monitoring has been used for the monitoring of patients suffering from a wide range of diseases such as: diabetes, hypertension, home delivery, home nursing care for elderly and chronically ill, and glaucoma, either through the use of voice or voice and video communication [START_REF] Hjelm | Benefits and Drawbacks of Telemedicine[END_REF][START_REF] Kassam | Teleglaucoma: Improving Access and Efficiency for Glaucoma Care[END_REF]. In this paper we address telemonitoring for glaucoma patients. Glaucoma is one of the major causes of blindness worldwide and its treatment requires frequent monitoring of patients [START_REF] Poon | Editorial: Special Issue on Health Informatics and Personalized Medicine[END_REF]. When the communication between patient and doctor has been done through V2V, prior research shows that although there is no cost saving between a tele-monitoring consultation and one in the hospital, patients were often satisfied with their personal cost and time savings that came as a consequence of using the system [START_REF] Tuulonen | The Application of Teleophthalmology in Examining Patients with Glaucoma: A Pilot Study[END_REF]. Among the drawbacks reported for remote consultation, poor image quality appears as one of the biggest issues impeding tele-monitoring.

Problems with the image quality have also been observed in conventional telemedicine [START_REF] Demartines | Assessment of Telemedicine in Surgical Education and Patient Care[END_REF]. Such problems have resulted in adequate information not being available for proper diagnosis of patients [START_REF] Shimizu | High-Quality Telemedicine using Digital Video Transport System over Global Research and Education Network[END_REF]. In a more recent study, Bradford et al. [START_REF] Bradford | Safety for Home Care: The Use of Internet Video Calls to Double-Check Interventions[END_REF] reported that problems with poor video quality in tele-monitoring contexts have led the nurse "to use a mobile phone for audio and the Internet video call for visual communication only, as the quality of the video could be improved by allowing more bandwidth" [START_REF] Bradford | Safety for Home Care: The Use of Internet Video Calls to Double-Check Interventions[END_REF]. In this respect, LiveCity aims to alleviate the problems that exist with the delivery of video over public internet infrastructure and facilitate the delivery of high definition video for the eHealth context as part of its portfolio.

Using High Definition Video in Tele-monitoring: LiveCity

As previous studies performed on video to video communication for tele-monitoring reported various difficulties encountered when delivering video over the Internet, such as poor image and noise quality [START_REF] Shimizu | High-Quality Telemedicine using Digital Video Transport System over Global Research and Education Network[END_REF], the LiveCity project aims to alleviate the problems that the transmission of high definition video over public Internet infrastructure faces, through the use of a Virtual Path Slice (VPS) controller (Fig. 1). While it is not our intention to discuss the technical characteristics and functions of the VPS controller in this paper, essentially it is an application that manages bandwidth by avoiding interference from unwanted traffic and therefore ensuring that any loss of delivered data and delays are reduced [START_REF] Chochliouros | Description and Thematic Context of the LiveCity Project[END_REF]. It therefore creates a virtual path over the public Internet to allow traffic (data, voice and video) to flow freely without losing quality. This ensures that signals are not interrupted by other external Internet traffic when the connection between two points of contact is established, therefore guaranteeing the transmission of high quality live video images between two points of contact.

Fig. 1. Video Platform with the Use of VPS Controller [21]

Transmission of HD V2V is particularly important for certain consultations for which the medical staff need to see detailed information. In this respect, the quality of images need to be very good, as is the case of glaucoma patients, where a high quality picture of the eye is necessary for a proper diagnosis [START_REF] Stamatelatos | Video-to-Video for e-Health: Use Case, Concepts and Pilot Plan[END_REF]. Glaucoma treatment usually consists on applying eye-drops, this being the preferred treatment to an operation. The treatment requires taking the medication in the same dose at the appropriate time and proper application of the eye-drops. However, it is reported that almost half of the patients fail to apply the eye drops correctly [START_REF] Stamatelatos | Video-to-Video for e-Health: Use Case, Concepts and Pilot Plan[END_REF], resulting in improper treatment of glaucoma leading to complications, side effects, eye-damage and vision loss. In such circumstances the communication between the doctor and the patient is extremely important for the success of the treatment. However, due to various reasons, such as convenience, cost or impossibility to arrive at a hospital premises or private clinic, communication and/or consultation between the patients and the healthcare provider can sometimes be difficult. This is especially significant in cases where patients are unable to physically visit their doctor due to disability or old age, or for those people living in remote locations. In this respect, tele-monitoring could help in consulting glaucoma patients and checking whether they take their treatment properly. In this paper we focus on the first phase of evaluating the tele-monitoring of glaucoma patients using HD V2V in the context of the LiveCity project and defining the KPIs to be used in the second phase for assessing the success of tele-monitoring in this context.

Evaluation

The purpose of the evaluation is to determine relevant Key Performance Indicators (KPIs) for successful adoption of video-to-video tele-monitoring for glaucoma patients. The LiveCity evaluation consists of two phases [START_REF] Weerakkody | Utilizing a High-Definition Live Video Platform to Facilitate Public Service Delivery[END_REF]. In the first phase, KPIs are determined. During the second phase, the obtained KPIs from the first phase are being applied to assess the LiveCity use case (in this case, the treatment of glaucoma patients using V2V tele-monitoring) and revise the KPIs. The revised KPIs will result in final recommendations for designing and implementing V2V tele-monitoring services for glaucoma patients.

The research presented in this paper focuses on the first phase. During this phase an initial set of KPIs are identified, followed by a revision of the originally obtained KPIs based on stakeholders consultations (in this case, interviews with doctors). The importance of involving relevant stakeholders in the implementation of ICT in public services in general [START_REF] Goel | Role of Key Stakeholders in Successful E-Governance Programs: Conceptual Framework[END_REF] [START_REF] Currie | Evaluating the Governance Structure for Public Sector IT: The UK National Programme in the Health Service[END_REF], and understanding doctors' perception of using HD V2V communication in particular is imperative before such services are implemented in healthcare settings to facilitate their adoption.

In this respect, it is important to find out what criteria are necessary to facilitate a successful adoption of HD V2V communication as proposed in the LiveCity project in the context of a healthcare setting. With this aim, we performed a preliminary interview with a doctor treating glaucoma patients at a large University Clinic hospital in Attica, Greece. This is the place where the LiveCity pilot will take place and the interviewed doctor will be involved in tele-monitoring glaucoma patients.

The interview was semi-structured with open-ended questions. Semi-structured interviews are the most common used tool in qualitative research in information systems [START_REF] Myers | The Qualitative Interview in IS Research: Examining the Craft[END_REF]. The interview was conducted in April 2013 and tape recorded with the doctor's permission. Since the purpose of this study was focused on the initial exploration of the concept of V2V used for the tele-monitoring of glaucoma patients, and not generalisation, a single in-depth interview was deemed adequate to fulfil the overall aim of the study.

Initial KPIs

In Table 1, we present the initial Use Case related KPIs we perceive to be important for evaluating the LiveCity platform, as drawn from the literature and consultation with LiveCity project partners. The technical KPIs related to the network connectivity and application are not presented in this paper as they are general to every LiveCity services and have been previously covered in [START_REF] Weerakkody | Utilizing a High-Definition Live Video Platform to Facilitate Public Service Delivery[END_REF][START_REF] Weerakkody | A Research Proposition for Using High Definition Video in Emergency Medical Services[END_REF]. The remaining KPIs have been organised into user requirements and process requirements.

User Requirements: these are related to the actual utilisation of the V2V service by the involved users and the respective level of user experience. KPIs are built around:

 Usability/Ease of Use: V2V services shall be easy to use by different classes of users,  Satisfaction: captures the different levels of user experience,  Reliability: reflects user point of view regarding reliability aspects of the V2V provision. Process Requirements: these are related to the end-to-end process tailored to the various V2V provision scenarios. In this case, in Table 1, we outline examples of the specific use case related KPIs for delivering health services using V2V. Ease of appointment scheduling (time required)

Table 1. Initial Health KPIs

Ease of appointment scheduling (ease of set up)

Refining the KPIs: Interview with the Doctor

After defining the initial KPIs from literature and secondary research, we conducted an in-depth interview with the doctor involved in treating glaucoma patients and who will be testing the tele-monitoring HD V2V solution offered by the LiveCity project. The purpose of this interview was to assess the criteria that are most important from his (the doctor's) point of view for the successful adoption of V2V in treating glaucoma patients. The interviewed doctor worked at the University Hospital Clinic responsible for treating (including performing surgical operations) patients with glaucoma in the Attica region as well as from across Greece who commute to the hospital for check-ups and treatment. In this particular case, it is anticipated that telemonitoring using HD V2V will facilitate better patient conformance to the right treatment and correct application of the eye-drops with the remote assistance from their doctor. Moreover, it is hoped that V2V will help patients access medical information remotely when needed and have their questions or queries answered with regards to their treatment. In the scope of the proposed activities, doctors will be able to interact with their patients and will be able to monitor them allowing frequent patient consultation during the medical treatment process. The high quality of live V2V will eliminate the necessity for patients to travel and visit their hospital and will allow doctors to monitor how patients apply their eye-drops and guide them to take corrective action when necessary. The necessity of refining the KPIs is motivated by the fact that the quality of service is mostly context dependent [START_REF] Babakus | An Empirical Assessment of the SERVQUAL Scale[END_REF][START_REF] Carman | Consumer Perceptions of Service Quality: An Assessment of the SERVQUAL Dimensions[END_REF][START_REF] Dabholkar | A Measure of Service Quality for Retail Stores: Scale Development and Validation[END_REF], with prior research showing failed attempts to measure it using general scales in new contexts [START_REF] Dagger | A Hierarchical Model of Health Service Quality Scale Development and Investigation of an Integrated Model[END_REF].

The interview with the doctor took place in April 2013. As a result of the interview, additional items were created and qualitative findings were matched with the existing scales to match construct definitions. During the interview, the doctor high-lighted the importance of some of the initial KPIs presented in Table 1, such as the importance of patient satisfaction with the system, "….if they [patients] are happy themselves, the patients who use the technology are satisfied, they will like it, will use it or we may even lose them in the process". In this process, the Doctor emphasised that the "video quality is the most important thing" due to the neccessity to see a detailed picture of the human eye.

Improved monitoring of patients by doctors "We [doctors] are always worried whether they [patients] use the drops correctly" "Patients underestimate the difficulty to put a drop into the eye, so we [doctors] can see them [patients] in their home and how they use the eye drops"

Improvement in the availability /easiness for patients to reach doctors "in case they [patients] want to ask something as an emergency … they will find it easier this way" "patients often complain that when they want to reach us [doctors], it is very difficult to get an appoitment" "through the V2V solution, they [patients] find it more easy to reach us"

Improve patient perception of doctor availability "feeling that we [doctors] are available for them [patients]"

Improvement in patient management "we [doctors] can decide whether they [patients] need to came or they can stay at home and continue the treatment…. This will help to reduce transportation costs" "..So many times they [patients] do not need to come to the hospital…it would be even better for us to decide if they need to come….. I believe that patient management as a result of using the system would be extremely better with V2V… not just better" Improvement in the number of patients treated "due to the improved patient management and less appointments and physical consultations, we will be able to treat more patients" Improve the patient skills/knowledge in applying their eye drops "Patients underestimate the difficulty of putting a drop into the eye"… "they [patients] need to be trained, educated, and reminded" Patient reliability in getting the treatment correctly "Ideally we would realise that patients who have been educated for the first month with more consultations, appoitments, video to video consultations could be more reliable with the treatment afterwards"

Discussions, Conclusions and Future Work

One of the clear benefits of using V2V enabled tele-monitoring is the ability to treat patients without the need for physical consultation and the need to be transported to a hospital. This could be particularly important for patients living in remote locations where access to the hospital is difficult, or for the elderly (who are most prone to be affected by glaucoma and require usually to be accompanied to the hospital) by allowing them to be independent for a longer period of time without the need to commute to the hospital. The purpose of this paper was to determine a set of KPIs aimed at assessing telemonitoring services for glaucoma patients. With this aim, we first identified generic KPIs from the literature, secondary sources and through consultation with the involved partners in the LiveCity project. This was followed by an interview with a doctor treating glaucoma patients at a large hospital in Athens, Greece. We presented the KPIs identified initially as well as the new ones obtained as a result of the interview.

From a theoretical perspective this study extends service quality research by developing a set of indicators for tele-monitoring patients who suffer from glaucoma. The implications of this research are highly relevant to the decision makers of eHealth platforms who are offering tele-monitoring services for glaucoma patients. These findings improve the general understanding of how doctors evaluate service quality in the context of glaucoma treatment using tele-monitoring. The proposed indicators should contribute to paving the way for conducting effective design of service delivery systems in the context of eHealth services.

Several limitations in this paper are worth noting. This research was conducted in only one country, and by interviewing only one doctor responsible for treating glaucoma patients. Replication in other contexts would increase the confidence in the proposed indicators; hence, the findings should be treated as indicative rather than confirmatory.

Once the V2V system is implemented for tele-monitoring of glaucoma patients in the context of the LiveCity project, we propose to refine the KPIs during the implementation and testing of the system and consequently propose a framework for evaluating the V2V enabled tele-monitoring of health services. The obtained KPIs and framework will then be used as a source to develop a 'how to' guide for delivering V2V based eHealth services.

  for the new system Learning time for new system use Time-to-doctor: meeting the doctor and starting the examination Physical presence cost including transfer to the hospital Waiting time in the hospital for examination Number of patients involved in the pilot Number of visits to the hospital (emergency) Number of visits to the hospital (outpatient) Waiting time in the hospital (emergency visit) Waiting time in the hospital (outpatient appointment) Number of patients Conformance to treatment Intraocular pressure control

Table 2 .

 2 New KPIs Identified for tele-monioring of Glaucoma Patients using V2V

	Criteria				Interview quote
	Improvement in the patients' health	"if they do not follow the treatment correctly, the eye will be lost"
					"if they put their drops correctly, maybe they need
					less bottles, less medicine, less eye drops… this
	Reduce the medication cost		means they do not pay extra money for medicine
					they do not need to use… often a lot of medicine is
					wasted because patient do not know how to use it"
	Improved	doctor	/	patient	"follow our patients more closely"
	communication
	Perespective
	Process

ACKNOWLEDGMENTS

The authors acknowledge the contributions made to this article by the LiveCity consortium of partners who are funded by the European Commission, especially to NKUA for helping in organising the study presented in the paper.