we would like to share with you what we are currently working on, with respect to the very core development of Thea. We always felt and feel that one of the strong points of Thea is the ability to render both biased and unbiased renders, an advantage over the other renderers. And we want to strengthen this point even further; and this goes through improving the Adaptive (BSD), i.e. our photon map / final gathering based engine.
This is not an "easy" job, but we have made a substantial progress with various new ideas, bringing BSD one step closer to perfection. Here are a few things that are completed and/or we are researching for further improvement.Improved Final Gathering / with Perceptual Estimation
Final gathering is improved, reducing blotches and making it more robust. Final gathering with perceptual estimation has been vastly improved in terms of speed & quality. This means that scenes with many lights and heavy geometry, like below, are rendered much faster now (and we are close to our goal for this specific one, rendering 1024p with good/high quality, under 1h on quad core).
File comment: A complex scene with ~65 million polygons and 120 elementary light sources (scene credits: Motiva Infografia).
victor_offices.png [ 414.42 KiB | Viewed 2839 times ]
Improved Photon Map Distribution
Photon map is getting substantially improved! One of the things we realized, was that, in certain cases, the distribution of the photons was not good. The distribution of the photons, plays a central role in having a smooth indirect lighting in BSD renders. Now, with careful observations, we managed to improve the distribution, make it more uniform and reduce considerably blotches that come later in the final gathering step. See below for a before/after comparison.
In the pictures below, we can see the global photon map directly. There are artificial lights placed in various positions inside the kitchen. There is also sun lighting that comes from a window behind
File comment: Sun lighting mixed with artificial lights has been producing uneven photon distribution, but now the situation is vastly improved (scene credits: George).
distribution_before_after.jpg [ 148.66 KiB | Viewed 2839 times ]
Effective Light Leak Removal
We have also moved further, with respect to removing unwanted light leaks in photon maps that can produce light blotches in final gathering step (which in many cases, FG cannot "hide" them). It is possible now to be very "harsh" on these leaks and prevent them altogether, improving the final result a lot. Here is a before/after comparison.
In the pictures below, we can see the final gathering pass with photon mapping, where the direct lighting is not included to show better the difference. The only light source is the sun, that comes through the windows on the left. Note that light areas on the BEFORE image, that are totally wrong, while the AFTER image has effectively removed them, while improving the quality at the same time (for example, the color bleeding of the ball & cube on the floor).
File comment: A simple interior rendered with same settings (250k photons) showing the irradiance pass only with effective light leak removal.
lightleaks_before_after.jpg [ 51.03 KiB | Viewed 2839 times ]
Last but not least, we do not stop here! One thing is for sure, Adaptive BSD will come much stronger in next release and we anticipate to see it being used more and more!