Terminator Artifact Treatment

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giannis
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Sun Dec 12, 2010 9:16 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).
terminator_artifact.png
Current revision showing terminator shading artifacts.
terminator_artifact.png (71.55 KiB) Viewed 13161 times
terminator_artifact_treatment.png
New (forthcoming) revision produces perfect/smooth shading, artifact-free.
terminator_artifact_treatment.png (70.15 KiB) Viewed 13161 times
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. ;)

best wishes
Science may limit knowledge but should never limit imagination - Bertrand Russell
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Javadevil
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Mon Dec 13, 2010 12:17 am

Ioannis, pure Genius !!

Must be the first Unbiased renderer to overcome the Terminator Artifact !
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blackice
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Mon Dec 13, 2010 5:30 am

giannis = terminator of (other) unbiased engine :lol:
http://www.ngonstudio.com
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19marco23
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Mon Dec 13, 2010 8:11 am

Semplicemente unici e mitici! Thank you!
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pckmark
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Mon Dec 13, 2010 9:58 am

giannis = terminator of (other) unbiased engine :lol:
:lol:

If i were the competition, i would cry right now :D

-Mark
They must find it difficult... Those who have taken authority as truth, rather than truth as authority
-G. Massey
smvwhite
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Mon Dec 13, 2010 11:13 am

Nice one Blackice. I have actually been waiting for a reference to Arnie. :lol:

Seriously, this is great news.
Last edited by smvwhite on Mon Dec 13, 2010 11:17 am, edited 1 time in total.
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SamHowell
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Mon Dec 13, 2010 11:16 am

You are right to be proud
e3d
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Mon Dec 13, 2010 11:57 am

Excellent work.. ;)
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kmarius
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Mon Dec 13, 2010 4:59 pm

Thanks Giannis! you are terminator!
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MrBraun
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Tue Dec 14, 2010 4:13 pm

Really great Giannis! :)

Just one question: can i write this news on my blog? :)
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