Reducing render times in MR

[Jonathan]

[ATTACH=CONFIG]39765[/ATTACH][ATTACH=CONFIG]39764[/ATTACH][ATTACH=CONFIG]39763[/ATTACH][ATTACH=CONFIG]39762[/ATTACH]Im working towards a short animation in Mental Ray, only problem is that the stills I have produced took nearly 40 minutes to render and thats just totally unacceptable for my approaching animation deadline. Some fairly basic settings really; 3 target lights, 150 rays per fg point, soft shadows precision:4, glossy reflections and refractions:2 and samples per pixel min-1 max-16. No GI. Any help on how to spped up the process would be most appreciated.

[Crazy Homeless Guy]

[ATTACH=CONFIG]39765[/ATTACH][ATTACH=CONFIG]39764[/ATTACH][ATTACH=CONFIG]39763[/ATTACH][ATTACH=CONFIG]39762[/ATTACH]Im working towards a short animation in Mental Ray, only problem is that the stills I have produced took nearly 40 minutes to render and thats just totally unacceptable for my approaching animation deadline. Some fairly basic settings really; 3 target lights, 150 rays per fg point, soft shadows precision:4, glossy reflections and refractions:2 and samples per pixel min-1 max-16. No GI. Any help on how to spped up the process would be most appreciated.

 

Things that slow down rendering... Soft Shadows, Glossy Reflections, Glossy Refractions. And placing a multiplier on these only makes matters worse.

 

High AA also contributes to high render times, but in this case I would say your ok as long as you haven't set the spatial contrast to low.

 

Do a material override, and check your rendering time. Eliminate all glossy reflections, and check your rendering time. Eliminate all glossy refractions and check your rendering time. Now, isolate bad materials and tweak them to be faster. In this case bad materials are the ones you have that are slowing down your scene.

 

I would not try to be physically accurate with your material when you are rendering an animation. Instead use educated judgments on what settings will allow you to convey the essence of the material while still making it fast and efficient.

Edited October 22, 2010 by Crazy Homeless Guy

[Jonathan]

Hey thanks Crazy Homeless Guy, very helpful. Regarding 'bad materials', how do you make a bad material good? Is this bitmap size, bump, blur etc? What are the most efficent ways to transform a begrudging material into a light, free and willing one?

[mskin]

i had issues initially. i set up a render farm at work. i just installed 3d max on a number of machines and ran the backburner server on them. read the backburner help, it was surprisingly easy to do. when its time to render, do a pre pass for the final gather (GI too typically, but apparently not in your case) and save them to a networked directory. make sure net render is selected for the final animation render.

 

i dont think its efficient to run an animation (as in avi or wmv) on a render farm so i set up the renderer to render all the frames as pngs or jpgs. the software will name them consecutively when they finish. each machine then participates in rendering each of the frames. when its done, it starts another until all the frames are finished.

 

finally, with a directory full of images, i use after effects to stich them back together. its worked great for me.

 

im by no means the most knowledgeable here in this matter, but this work flow has worked great for me. good luck.

[Justin Hunt]

With out seeing you settings its quite difficult to trouble shoot.

 

For your scene you problably could go for really low FG settings, like Draft, with a high FG interpolation setting. Of cause calculate every nth frame, freeze fg solution and re-render. You might even get away with 0 Bounce FG.

 

The glossie multipiers are problably the worst and last settings to play with.

 

For really glossie materials, where true reflections are not essential, try setting the refections to Highlights&FG only.

Set attenuation ON All lights, this will really speed things up. Shadow samples could also be lowered as well.

 

jhv

[maciejwypych]

Set the quality of you reflection/refraction in your materials and not by setting the multiplier, it will give you more control over the materials that actually need better quality and not the whole scene.

Also keep in mind that you don't need to calculate final gather for every frame, just every 5th or even 10th depending the speed of your camera.