More on the subject:B.Y.O.B. wrote: ↑Fri Feb 23, 2018 7:27 pmYes, I remember an article about the feature in Thea but I can't find it anymore.
The only thing they offer is an example image, scroll to the bottom of this page: https://www.thearender.com/site/index.p ... iased.html
However I don't know if their workaround/hack is truly unbiased (but if it works, I'm not complaining about a little bias).
Terminator Artifact Treatment (@ Thea Render Forums),
based on "It's Really Not a Rendering Bug, You See…"
from "Mistakes to Make on a Raytracer" (@ geekshavefeelings.com)
IIRC, Corona dev. mentioned setting epsilon value to resolve the issue.Terminator Artifact Treatment
by giannis » Sun Dec 12, 2010 10:16 pm
In the next revision to come, there is an important fix, for a problem known as the "terminator artifact". For your information, this artifact is seen at the limit of lighting models that have low-poly subdivision (it is more obvious in low-poly meshes - it actually can be seen on arbitrarily detailed meshes on close up). It is very nicely described in this paper where it is identified as an inherent render artifact rather than a bug! This is why, you probably have seen this in a lot of other renderers as well.
As far as we know, the majority of unbiased renderers suffers from this problem. In biased renderers, it is somewhat easier to fix the problem. A nice (biased) solution used, is to appropriately tweak the material reflectance, compressing it and "pushing out" the jaggy artifacts. If an inherent solution does not exist on the renderer, the typical workaround is to subdivide models to a finer degree (something that costs both memory and speed).
In Thea Render, we didn't want a solution that could alter/bias material appearance but instead we very carefully compensate for the energy loss due to the terminator artifact dark zones. Our solution produces smooth renders even for very low-poly models with only the basic assumption that the subdivision is uniform (i.e. not abruptly changing). We are actually very happy that we have this working out-of-the-box for all engines. As an example, you can see in the images below some spheres rendered with sun light in current and next (forthcoming) revision (note that the spheres have increasing subdivision detail from left to right).
Current revision showing terminator shading artifacts.
New (forthcoming) revision produces perfect/smooth shading, artifact-free.
With this enhancement, Thea moves ahead and we believe as an established world class renderer, quality-wise. We are proud of making Thea better and we hope that you are proud of being a Thea user and getting artifact-free renders - getting ahead of unbiased competition.