14 hours…
reason?
I dont know…setup is: displaced frost object over the displaced pipe. The frost is refracting…the scene is lit by 1 light and hdri is reflecting.
Gi is quasi. Everything else is procedural textures with some other textures…in my opinion this has to render in no longer then few minutes, well with quasi maybe more, but not 14 hours.
the scene is here if anyone cares to pick at it (Vlado please) http://www3.telus.net/public/vinnik88/temp/procedural\_Frost.rar
I think vray has a problem with calculating displacement and any type of refraction. This is second time this week i get into such situation. First time was with sss, but I thought that sss/displacement just dont like eachother.
Dmitry, I just tried to render your file and slow it is!
I turn the indirect illumination off and it rendered in a minute.
Have you tried it without the SciAnaComp maps?
hmm…that might be part of it…
i will reasearch it soon. So far I only know and noticed, that rendering speed drops when it renders the part where the two maps blend between eachother. In any instance where blending occurs vray has hard time.
ok here is what i got: partially i think the problem lies within 3ds max itself. I am using blend material to blend between two shaders as the frost progresses. When i setup a simple test where there was a blend between max standard and vray mtl i rightaway noticed that second blending material (max standard) would take some time to render. I couldnt understand why, then i made vray mtl glass (reflective/refractive) and the rendering on the max standard material increased even more. So I thought - vray has some problem with blend. Then i tried same setup with brazil and…brazil rendered it 10 times slower then vray. Same fell for scanline and mental.
So my conlusion is that I dont know why but blend is very slow when compositing against refractive/reflective object.
This is because for a Blend material, all lighting calculations must be performed twice - once for each material. This is not such a problem normally, but when you consider GI and refractions, things get very problemmatic. If you have nested Blend materials, the situation deteriorates rapidly. VRay tries to avoid this issue to some extent, but there is no good work-around.
Instead of using a Blend material, you can use just 1 material and vary the corresponding properties of the surface - e.g. a map for the refraction color/glossiness/whatever. Often, you can get the same effect, and it will render a lot faster.
This goes for other materials too. Instead of using a compound material, use one material with maps to vary its properties.
BTW Dmitry, I have looked at the sss/displacement thingy, but I didn’t have much time to tinker with it; hope to have some today.
Don’t mean to hijack the thread, but I’ve never heard this about a blend material. As to your mapping workaround, I don’t follow. Do you mean using mix maps in each slot as necessary?
Vlado thanks…
I will also continue working on that scene. As to this one, I think per pass is the solution.
However we should not need to do this. Maybe later when vray 1.5 is out (this could turn into a wish thread) but you guys can script some nice vray shaders to allow blending and other composit modes with fast performance and all.
On the other hand, max 8 is going to be around soon. Who knows what it will bring.
What about Multi/Sub-Object materials? Do they also require more computing time? I’ve got a scene that uses one big Muti/Sub material and just a few single materials and it renders quite slow.
yeah its a max limitation. Im gon do some tests in maya to see if it works any differently…if so then I will request autodesk in next release to fix this.
