1. Real-Time Rendering of Planets with Atmospheres
Tobias Schafhitzel, Martin Falk, Thomas Ertl
Universität Stuttgart, Germany

2. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Motivation
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

3. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Outline
Introduction
Atmospheric scattering
Computation of the scattering texture
Rendering
Results
Conclusion and future work
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

4. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Outline
Introduction
Atmospheric scattering
Computation of the scattering texture
Rendering
Results
Conclusion and future work
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

5. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Introduction
Rendering a planet’s atmosphere
Physically based computation
color shifts, light attenuation
Sunset, sunrise, midday
Combination with terrain rendering
Real-time approach
Games
CAD
Explorative tools (i.e. Google Earth,…)
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

6. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Previous Work
Atmospheric Scattering
Atmospheric Scattering Effects of the Earth [Nishita et al. 93]
Real-Time Atmospheric Scattering [O’Neil 04]
Interactive Rendering of atmospheric Scattering Effects using
Graphics Hardware [Dobashi et al. 02]
Accurate Atmospheric Scattering [O’Neil 05]
Terrain Rendering
Real-Time continuous Level of Detail Rendering of Height Field
[Lindstrom et al. 96]
Real-Time Generation of continuous Level of Detail for Height Fields
[Röttger et al. 98]
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

7. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Outline
Introduction
Atmospheric scattering
Computation of the scattering texture
Rendering
Results
Conclusion and future work
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

8. Atmospheric Scattering
Light scattering equation: Pv Pc Pa
atmosphere φ Pb
earth
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

9. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Outline
Introduction
Atmospheric scattering
Computation of the scattering texture
Rendering
Results
Conclusion and future work
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

10. Computation of the scattering texture
Parametrization of the 3D scattering texture:
Arbitrary height h = |Pv|
For each h Arbitrary view angle θ
For each θ an arbitrary angle to the sun φ φ θ Pv h
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

11. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Intersection Tests PV PV
Camera inside the atmosphere
→ use 1st intersection
Camera outside
→ no scattering
→ move camera to outer boundary
→ constant height for parameterization
→ use 2nd intersection
Two textures for intersections with
Inner sphere
Outer sphere
Easy to switch when rendering PV
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

12. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Outline
Introduction
Atmospheric scattering
Computation of the scattering texture
Rendering
Results
Conclusion and future work
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

13. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Rendering the sky
Sky: tessellated sphere
View ray Rv
connect vertex Pg with camera Pv
Compute h, θ and φ and map to [0,1]
φ is constant (directional light)
Fetch the scattering texture (simple lookup) Pc Pg φ θ Rv Pv
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

14. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Rendering the terrain
More complex
Consider structure of the terrain
Naive computation fails
Distance too long
Terrain color not considered
Solution
Compute scattering along PvPb
Subtract contribution along PgPb
Two texture lookups: PV Pg Pb
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

15. Rendering the terrain II
Considering the terrain color
Illumination of the terrain
Incident light is attenuated:
Reflected light is attenuated
Overall light contribution: Pc Ig PV
Igv Pg
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

16. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Outline
Introduction
Atmospheric scattering
Computation of the scattering texture
Rendering
Results
Conclusion and future work
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

17. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Results
Earth dataset (2572 x 24 x 12)
Mars dataset (652 x 24 x 12)
Earth
Mars
Outside
67.26
83.51
Inside
30.31
56.02
Terrain outside
76.44
102.37
Terrain inside
35.83
61.19
All measurements in fps
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

18. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Europe at morning
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

19. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Alps at morning
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

20. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Alps at midday
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

21. Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres
Sunrise
Tobias Schafhitzel – Real-Time Rendering of Planets with Atmospheres

22. Questions ?