Master 2008-2009
Real-time amplification of digital elevation models


Eric Bruneton


The research work about terrain modeling and real-time high quality rendering at Evasion.


The publicly available, most precise digital elevation models for the whole Earth have a resolution between 500 and 90m per pixel. This is sufficient for high altitude views, but not for ground views, where the lack of details seems unrealistic. Without more precise global data the only solution is to generate the missing details. These details must be plausible, and it must be possible to generate them on the fly (a precomputation would be too long and would generate to much data).

Several methods have been proposed to amplify digital elevation models. [1] and [2] use a multi resolution analysis ([6], [7]) in order to add details that adapt to the local terrain shape (plains or mountains). But with these methods the added details are isotropic, which is not realistic. [3] proposes an approach inspired from the texture synthesis methods ([4], [5]) in order to solve this isotropy problem. In order to add details at a point P, the idea is to look for, in a high resolution model, a zone that is "similar" to the one around P in the model to be amplified, and then to transfer the details of the high resolution model to the low resolution model. This method gives better results but it is too slow for a real-time application ([2] is real-time but does not give realistic results).

In this context the goal is to propose a real-time method to amplify a digital elevation model of the whole Earth, and that can produce plausible details. For this it might be useful to borrow ideas from the real-time texture synthesis algorithms on the GPU ([4], [5]). The proposed method will be evaluated by integrating it in the terrain rendering software of EVASION, which can render the whole Earth at all scales.


[1] Adding Synthetic Detail to Natural Terrain Using a Wavelet Approach
Perez M., Fernandez M., Lozano M., LNCS 2002

[2] Geometry Clipmaps: Terrain Rendering Using Nested Regular Grids
Losasso F., Hoppe H., SIGGRAPH 2004

[3] Terrain synthesis by example
Brosz J., Samavati F. F., Sousa M. C., GRAPP 2006

[4] Appearance-space texture synthesis
Lefebvre S., Hoppe H., SIGGRAPH 2006

[5] Parallel controllable texture synthesis
Lefebvre S., Hoppe H., SIGGRAPH 2005

[6] Generalized B-spline Subdivision-surface Wavelets for Geometry Compression
Bertram M., Duchaineau M. A., Hamann B., Joy K. I., TVCG 2004

[7] Dyadic Splines
Duchaineau M. A., PhD thesis, 1996

[8] Terrain Synthesis from Digital Elevation Models
Zhou H., Sun J., Turk G., Rehg J. M., TVCG 2007

[9] Terrain modeling: a constrained fractal model
Belhadj F., AFRIGRAPH 2007