Graphics Reference
In-Depth Information
Unfortunately, due to our tight release schedule, we didn't have time to find a
better solution that both improves quality and maintains acceptable performance.
3.8.2 Epipolar Sampling
To improve our rendering performance, we have reduced the amount of ray-march
samples by lowering the resolution of our volumetric light buffer. Epipolar sam-
pling [Yusov 14] also dramatically reduces the number of ray-march samples.
However, instead of lowering the resolution in screen space, it reduces the res-
olution across the epipolar lines from the light source relative to the viewer's
position. Lowering the resolution across these lines is far less noticeable. By
using epipolar sampling we should be able to reduce the amount of pixels for
which we execute the ray-march loop even more without losing or maybe even
improving quality.
3.9 Conclusion
We have shown a practical implementation of volumetric lighting effects as being
used in
Killzone: Shadow Fall
. Using half-resolution buffers and dithered ray-
march offsets, we have improved performance and maintained good image quality.
We managed to give the artist full control over the intensity of volumetric
light in our scenes by using particles to render a 3D texture that defines the
amount of light scattering.
By rendering another 3D lookup texture that defines the intensity of volu-
metric light over depth, we solved most of the compositing problems related to
transparent objects.
Although there are limitations to our approach, it does show a solution that
deals with the problems we have found during the development of the volumetric
light effects in
Killzone: Shadow Fall
.
Bibliography
[Bayer 73] Bryce Bayer. “An Optimum Method for Two-Level Rendition of
Continuous-Tone Pictures.”
IEEE International Conference on Communica-
tions
1 (1973): 11-15.
[Henyey and Greenstein 41] L. G. Henyey and J. L. Greenstein. “Diffuse Reflec-
tion in the Galaxy.”
Astrophysical Journal
93 (1941), 70-83.
[Lokovic and Veach 00] Tom Lokovic and Eric Veach. “Deep Shadow Maps.”
In
Proceedings of ACM SIGGRAPH 2000, Computer Graphics Proceedings,
ACS
, pp. 385-392. New York: ACM, 2000.
