Résumé :

In this paper we present a research related to the virtualization of an old town scale model. This is an experimental work that mainly focuses in establishing a valid workflow from data remote sensing to the real- time on-line walkthrough in the 3D model.
The real scale model encompasses the town itself and the surrounding countryside. Because the scale model is kept safe in containers, nobody has access to this information. Providing an on-line virtual model will unveil both the scale model and its attached information to the general public. In this paper we present the application we have developed for the visualization of the virtual model, using a game engine. After an introduction, each of the following topics will be developed:
Choice of Unity software: although Unity is a real time 3D engine devoted to video game development, we justify our choice to develop in this environment and explain how its API is appropriate to achieve our goals. Terrain: scanned with a hand-held laser scanner, we focus on how we have overcome some difficulties to optimize the terrain management. Buildings: when some geometry is imported in Unity, new textures are created. We have developed a modeling environment so that all the buildings easily share a set of common textures. Vegetation: the challenge was to create new kinds of vegetation that look like the ones on the scale model, that's-to-say not so realistic. We also have developed a tool to "plant" vegetation on the terrain at accurate locations.
Results and future work: we present result analysis and extrapolation of the workflow to the entire scale model that is twenty times greater in size than the part we have modeled. The workflow has been set keeping in mind that the visualization of the whole scale model on the web will be a challenge: 4000 buildings and more than 870 000 vines on a large terrain.

Keywords: architectural heritage, laser scanning, game engine, town scale model

• BUR Didier
• CHEVRIER Christine
• HUMBERT Pascal