2. Main Goal Development of an application that allows flying virtually over El Hierro Island (Canary Islands), showing the building structures of a hydroelectric power station that is in construction.

3. Input data: Aerial photos 66 TIFF images of 2.500 x 2.500 pixels 1:5.000 scale of the island surface (1 m2 per pixel).

4. Input data: Height map Rectangular grid with data value each 10 meters. 3.000 points 2.500 points

5. Input data: Building and structures design Planes and designs of buildings and structures of the power station (including one new harbour).

6. Development tool used Free and portable game development kit It supports funcionality to: –handle large poligonal meshes, –moving around a 3D world, –show atmospheric and light effects to make the scene more realistic.

7. LOD Algorithm The whole island is covered by a triangle mesh, created from the input height map. This mesh is composed of 66 simple meshes of 250x250 triangles (approx. 62 thousand). Total for the island is more than 4 million of triangles. A LOD (Level Of Detail) algorithm is used to simplify meshes too far from viewer.

8. Texture mapping 2.500 x 2.500 1 pixel = 1m 2 2.048 x 2.048 1 pixel = 1.5 m 2 Aerial photos are texture mapped on every mesh. Every texture is re-dimensioned to 2.048 x 2.048 (power of 2)

9. Mipmapping We use an special file format to store the mipmap data on every image. A mipmapping algorithm decides the detail level of each texture according to the distance to viewer. 2.048 x 2.048 1.024 x 1.024 512 x 512 256 x 256

10. Generation of the sea Represented by a single large polygon, mapped with a synthetic sea photo. Next, every aerial photo that include sea areas was processed to blur the real sea. This allows to avoid the visual discontinuity between real and sinthetic sea.

11. Sky representation The sky is represented by a semisphere. A synthetic sky with clouds was generated and texture mapped on the semisphere. In areas close to horizon, the sky was blurred to achieve a more realistic effect.

12. Buildings design Every structure of the power station was designed with a 3D modeller software and located in the exact position over the island.

13. Natural structure design Some natural structures was designed. It achieves a 3D effect when the camera approach, much better that using just the 2D photo viewed from the top.

14. Interface design

15. R Automatic flights between two points A Current view direction B Final view direction 2. Straight line 3. Final rotation 1. Initial rotation Between a point A with an initial orientation, to a point B with a final orientation.

16. Collision detection y x, z Height of viewer Height of terrain under viewer position We have to avoid that viewer crosses the terrain

17. Visualization of names y x, z Population d View direction View up vector Visualization of names of populations and interest places over their exact location on the island.

18. Information panel visualization y x, z Interest place d View direction Generation of information panels, with photo and text. Application must show the suitable panel in every moment, depending on the place flown over.