Speculars look bad on MentalRay (ArchMat)

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caledonian_tartan
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Speculars look bad on MentalRay (ArchMat)

Post by caledonian_tartan » 18 Dec 2014, 09:18

i used VRAY a lot lately.

now trying Mental Ray again i recognized strange behaviour on specular highlights.
using the default settings, they look blown out.

any idea?
Highlights.jpg
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Hirazi Blue
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Re: Speculars look bad on MentalRay (ArchMat)

Post by Hirazi Blue » 18 Dec 2014, 10:06

Could it be the following gotcha?
IMPORTANT:If you are not using anisotropic reflections, type "None" into the Transparency/Reflection > Anisotrophy > Texture Space selection box to avoid artifacts in the render.
(Quoted from here)
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caledonian_tartan
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Joined: 17 Feb 2010, 15:13

Re: Speculars look bad on MentalRay (ArchMat)

Post by caledonian_tartan » 18 Dec 2014, 10:29

some dots disappear when setting to "none". but the sampling (AA) of the speculars remains poor...
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ActionArt
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Re: Speculars look bad on MentalRay (ArchMat)

Post by ActionArt » 18 Dec 2014, 16:14

The specular on the that shader was always pretty much useless. You can bypass it by using another shader (such as blinn or whatever you want) and plugging it into the architectural shader (global settings / additional color) and turning off everything in the blinn except the specular. This will use just the specular from the blinn and the rest is still the architectural shader.

Kzin
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Re: Speculars look bad on MentalRay (ArchMat)

Post by Kzin » 28 Dec 2014, 18:33

if you use the highlight mode, then yes, it might looks blown out because its just a highlight and not an actual light reflection aka direct reflection.

real light reflections might be a problem with glossy reflections because the mia shader misses MIS, which means its sampling randomly without concentrating on important things. that also means dimmed light reflections with low material glossy sample counts. so it might be noisy except you use high local glossy sample counts, which can end up in really high raycounts but you will have brighter light reflections because more random rays are hitting the light source so more rays will contribute for the light reflection on the object.
keep in mind the mia mat was not designed for that usage in mind (i dont know which users gave their input back these days as mia was coded, but there was alot of user input). mila and mdl will solve it, but not in si anymore but watch out for the new maya version.

the blinn shader highlight might be stronger, but its not correct at the end because its possible to get more intensity for specs when it should be because its not energy conserving.

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