Also in this issue:

Keynote: by Kostas Glinos

Joint ERCIM Actions:Future Research Challenges inSoftware Evolution andMaintenance – Report fromEC Expert Meeting

R&D and Technology Transfer:IT Security: Risk-BasedPrediction Tool and Method forCritical Infrastructures

Simulation& Modelling

for Research and Industry

Computational Science/Scientific Computing

Special theme:

ERCIM NEWSEuropean Research Consortiumfor Informatics and Mathematicswww.ercim.eu

Number 81, April 2010

only valid during trajectories of givenlengths, which may be very short.

Our work in the Nonlinear Dynamics,Chaos and Complex Systems Group atthe Universidad Rey Juan Carlos(URJC) in Madrid, is focused onanalysing and plotting predictabilitycharts for certain models. We get theshadowing times by computing thefinite time Lyapunov exponent distribu-tions. Each computational run is basedon the integration of one initial condi-tion with a well-known Runge-Kutta-Fehlberg integrator scheme. As the inte-gration progresses, the distribution iscalculated and the instability and hyper-bolicity indexes are derived. This isrepeated for several conditions andparameters, thus returning a completedescription about the predictability ofthe used model.

Note that this strategy is very wellsuited for high-throughput (Grid)numerical schemas. A set of shell scriptsfeeds the integrator with the proper ini-tial conditions and a grid engine (in ourcase, GridWay) and submits the processto the proper cluster in a user trans-parent way.

These techniques are general enough tobe applied to different models withminor modifications. Our work focuseson galactic modelling, where theapplied timescales are critical.Mathematically meaningful timescalescannot be physically acceptable here. Aparticle being shadowed during only afew crossing times (cycles) is a criticalissue. Galaxies are evolutionary enti-ties, from the point of view of both theirgravitational potential and their con-stituents. For instance, in a Milky Way

type model, the older stars will haveorbited the galactic centre just sixtytimes before death. And the galaxyitself may evolve during this shortperiod of time. Interpreting the dynam-ical system in a broad sense, given aninitial condition, the stability refers tothe location itself, not to the tracer parti-cles. But considering what happens tothe model in such short timescales, andfor the sake of our discussion, the fore-cast of the numerical galactic modelreliability is then of importance.

Link: http://www.fisica.escet.es

Please contact:

Juan C. VallejoUniversidad Rey Juan Carlos, Madrid,SpainTel: +34 91 8131366E-mail: juancarlos.vallejo@urjc.es

ERCIM NEWS 81 April 2010 13

The established practice in computervision, graphics and pattern recogni-t ion is to base inferences only onrestricted information. Virtual realityapplications typically use oversimpli-fied models that cannot even remotelyapproximate the appearance of realscenes, meaning human observers caneasily differentiate between real andvirtual scenes. Fortunately, the recentswift development of computer tech-nology has allowed models and toolsthat seemed theoretical only a decadeago to become feasible as a part offoreseeable future routine processes.Physically correct and accurate mate-rial appearance visualization is in highdemand. It not only has a huge eco-nomic impact in visual safety simula-tions and virtual design in automotiveindustry and architecture, but also haslarge potential in visual scene analyt-ical applications, including health care,security, defect detection and content-based image retrieval. However, many

challenging problems still exist, suchas efficient measurement of materialoptical properties, image compression,optimal mathematical representation,unsupervised segmentation and inter-pretation and many others.

We have developed several multidi-mensional probabilistic models basedeither on a set of underlying Markovrandom fields or probabilistic mixtures,which allow physically correct surfacelossless representation and modelling,huge measurement space compression(so far unbeaten at up to 1:1 000 000),and even modelling of previouslyunseen surface data or their editing.These methods are parametric, so theydo not require original measurementsto be stored. However, such models arenontrivial and suffer from several chal-lenging theoretical problems such asstability, parameter estimation and non-iterative synthesis, which must be cir-cumvented.

Alternative approaches using physicalreflectance models or sophisticatedsampling were also investigated.Regardless of the traits of individualmodels, they all meet comprehensiblerequirements such as unlimited seam-less surface image enlargement, highvisual quality and compression, as wellas some less obvious features like strictseparation of the analytical and syn-thesis parts, possible parallelization andimplementation in advanced graphicshardware. Unfortunately, there is noideal universal visual surface mathe-matical model suitable for all applica-tions or material types. Each of theseaforementioned models have theiradvantages and drawbacks simultane-ously, hence optimal measurement aswell as modelling depends on bothmaterial and intended application, andmust be automatically recognized.Surprisingly, the reliable assessment ofvisual quality is also a difficult taskbecause no usable mathematical crite-

Realistic Material Appearance Modellingby Michal Haindl, Jiří Filip and Martin Hatka

Physically correct and realistic visual appearance rendering or analysis of material surface visualproperties require complex descriptive models capable of modelling material dependence on variableillumination and viewing conditions. While recent advances in computer hardware and virtualmodelling are finally allowing the view and illumination dependencies of natural surface materials tobe taken into account, this occurs at the expense of an immense increase in the required number ofmaterial sample measurements. The introduction of fast compression, modelling and renderingmethods for visual data measurements is therefore inevitable.

rion exists and such verificationrequires costly and time-demandingpsychophysical visual evaluation. Onthe other hand, we have successfullyapplied methods of visual psy-chophysics to the development of evenmore efficient material-dependent com-pression and measurement methods.

We believe that the combination of per-ceptually optimized measurement andeffective mathematical representationof surface appearance is a key to thewide applied usage of realistic view-and illumination-dependent surfacematerial optical measurements.

Links:

http://ro.utia.cas.cz/10cvpr_tutorial/http://staff.utia.cas.cz/filip/projects/pertex

Please contact:Michal Haindl - CRCIM (UTIA)Tel: +420 266052350E-mail: haindl@utia.cas.cz

ERCIM NEWS 81 April 201014

Special Theme: Modelling and Simulation for Research and Industry

Figure 1: Examples of the realisticrendering of view- and illumination-dependent textures in a car interior,on virtual drapery and on anenvironmentally lit tablecloth.

POSEIDON, a project co-funded by theEuropean Commission, DGEnvironment, Civil Protection Unit, aimsto design, organize and evaluate an oper-ational civil protection exercise involvingGreece, Cyprus and France, addressingthe results of a hypothetical extreme dis-aster caused by an earthquake of consid-erable magnitude followed by a tsunami.This hypothetical disaster will devastatethe island of Crete and will require theinvocation of the European CivilProtection Mechanism to bring assistancefrom other areas in Greece, France andCyprus. The aims of POSEIDON are: (a)to understand, verify and improve civilprotection procedures for preparednessand response, particularly in relation toearthquake events followed by tsunamis,(b) to provide a learning opportunity forthe actors involved in civil protectionassistance interventions, (c) to test thecoordination of EU civil protection assis-

tance particularly through theMonitoring and Information Centre(MIC), and (d) to validate new applica-tions for early warning and communica-tions systems as well as procedures bywhich to inform the public of emergencymeasures to be undertaken.

FORTH-IACM, and specifically theLaboratory of Coastal Research &Applications is responsible for per-forming a risk assessment study that willprovide the hypothetical disaster sce-nario from a large earthquake and thetsunami that follows, using advancedsimulation techniques. The risk assess-ment study involves the production oftsunami inundation and seismic inten-sity maps to be used before the exerciseby the emergency planners to preparetheir response and then during the opera-tional exercise when additional localscenarios will be added to overwhelm

the local command and control anddirect search and rescue operations.

We take as our starting point the histor-ical earthquake of 365 AD that occurredin the sea west of the island of Crete andwhich was followed by a tsunami.Historical sources report that this partic-ular earthquake caused extensivedestruction, and this has been verifiedby contemporary seismological and geo-logical research (Shaw B, AmbraseysNN, England PC, Eastern Mediterraneantectonics and tsunami hazard inferredfrom the AD 365 earthquake, NatureGeoscience 1, 268 - 276 (2008) ). Apartfrom the destruction, the earthquakecaused significant geological distur-bances, particularly acute in the west-ward coast of the island.

The reconstruction of the earthquakecharacteristics from bibliographical

Risk Assessment Study based of the 365ADEarthquake to Drive a Civil Protection Exercise by Evangelia T. Flouri, Costas E. Synolakis, Nikos A. Kampanis and Catherine E. Chronaki

The simulation of the extreme destructive historical earthquake of 365 AD in the Aegean Seawill help to draw a realistic disaster scenario to test EU member state collaboration in the frameof the European Civil Protection Mechanism.

ERCIM is the European Host of the World Wide Web Consortium.

Institut National de Recherche en Informatique et en AutomatiqueB.P. 105, F-78153 Le Chesnay, Francehttp://www.inria.fr/

Technical Research Centre of FinlandPO Box 1000FIN-02044 VTT, Finlandhttp://www.vtt.fi/

Irish Universities Associationc/o School of Computing, Dublin City UniversityGlasnevin, Dublin 9, Irelandhttp://ercim.computing.dcu.ie/

Austrian Association for Research in ITc/o Österreichische Computer GesellschaftWollzeile 1-3, A-1010 Wien, Austriahttp://www.aarit.at/

Norwegian University of Science and Technology Faculty of Information Technology, Mathematics andElectrical Engineering, N 7491 Trondheim, Norwayhttp://www.ntnu.no/

Polish Research Consortium for Informatics and MathematicsWydział Matematyki, Informatyki i Mechaniki, Uniwersytetu Warszawskiego, ul. Banacha 2, 02-097 Warszawa, Poland http://www.plercim.pl/

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Consiglio Nazionale delle Ricerche, ISTI-CNRArea della Ricerca CNR di Pisa, Via G. Moruzzi 1, 56124 Pisa, Italyhttp://www.isti.cnr.it/

Centrum Wiskunde & InformaticaScience Park 123, NL-1098 XG Amsterdam, The Netherlandshttp://www.cwi.nl/

Foundation for Research and Technology – HellasInstitute of Computer ScienceP.O. Box 1385, GR-71110 Heraklion, Crete, Greecehttp://www.ics.forth.gr/

FORTH

Fonds National de la Recherche6, rue Antoine de Saint-Exupéry, B.P. 1777L-1017 Luxembourg-Kirchberghttp://www.fnr.lu/

FWOEgmontstraat 5B-1000 Brussels, Belgiumhttp://www.fwo.be/

FNRSrue d’Egmont 5B-1000 Brussels, Belgiumhttp://www.fnrs.be/

Fraunhofer ICT GroupFriedrichstr. 6010117 Berlin, Germanyhttp://www.iuk.fraunhofer.de/

Swedish Institute of Computer ScienceBox 1263, SE-164 29 Kista, Swedenhttp://www.sics.se/

Swiss Association for Research in Information Technologyc/o Professor Daniel Thalmann, EPFL-VRlab, CH-1015 Lausanne, Switzerlandhttp://www.sarit.ch/

Magyar Tudományos AkadémiaSzámítástechnikai és Automatizálási Kutató IntézetP.O. Box 63, H-1518 Budapest, Hungaryhttp://www.sztaki.hu/

Spanish Research Consortium for Informatics and Mathematics,D3301, Facultad de Informática, Universidad Politécnica de Madrid,Campus de Montegancedo s/n,28660 Boadilla del Monte, Madrid, Spain,http://www.sparcim.es/

Science and Technology Facilities Council, Rutherford Appleton LaboratoryHarwell Science and Innovation CampusChilton, Didcot, Oxfordshire OX11 0QX, United Kingdomhttp://www.scitech.ac.uk/

Czech Research Consortium for Informatics and MathematicsFI MU, Botanicka 68a, CZ-602 00 Brno, Czech Republichttp://www.utia.cas.cz/CRCIM/home.html

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ERCIM – the European Research Consortium for Informatics and Mathematics is an organisation

dedicated to the advancement of European research and development, in information technology

and applied mathematics. Its national member institutions aim to foster collaborative work within

the European research community and to increase co-operation with European industry.

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