out of memory and mental ray

MikeF

So i've started doing some render tests for my 3d final, as of late i've been getting an out of memory error when rendering with mental ray +physical sun/sky. I cant for the life of me figure out what is causing this, i've played with all the optimization settings i can think of, i've deleted tons of detail from my backgrounds, but i always get the same problem. I'm able to render like 8-9 frames in a row, then maya becomes unstable, i get the out of memory error and i have to restart. This is really starting to scare me, i only have about a month left for final renders and this cant be hapening.

I was able to crash my rendering farm of 12 quad core 3.4ghz
3gb after only a couple hours into the latest render, meanwhile just a few weeks ago my last render test took 6 hours to complete and the only thing i can think of thats been added since was a bit of new animation, some background details and textures. Do textures really bog down mental ray, if so should i just shrink every texture as much as i can and try that?

Illusions

What file format are your textures? If any of them are .tiff/.tif convert them to something else because MentalRay doesn't like them. Have you changed your render settings at all since just clicking the create physical sun/sky button?

Mark Dygert

Normally memory errors at render time are textures or shadow mapped shadows. Shadow Map is bitmap for that light, smaller maps are quicker and can be blurred but larger maps give better shadow detail. Depending on how big you've set the map size per light, it could eat up a ton of memory.

If the lights are set to ray trace and you're using a lot of omni lights you could be sending a ton of rays in directions and they are going to areas you don't really care about. In that case switching to spot or direct lights can help point those rays where they will all count. So instead of using 1000 rays all over the place trying to get 25 to land in one particular spot, switch to spot and only send out 25.

6hrs seems like a really long render time even when using MR sky/sun with settings cranked.

Shadow generation and reflections are by far the biggest drain at render time so make sure if you only have lights set to cast shadows when it is absolutely needed. If every light in the scene is set to cast shadows theres a good chance its what is slowing you down.

It would help if you could show a screen grab of the scene and explain what type of lights you're using?

MikeF

6 hrs was for 1800 frames.
all my textures are 24 bit targas, i just went through and cut the dimensions in half for everything, so i'm giving that a go with a batch render now.
Currently there is only one directional light in the entire scene which is the sun direction for the physical sun/sky.
I've been reading about memory conservation and MR rendering, one thing that comes up pretty often is some sort of option that loads the textures into temporary HD space, cant really see any options like that in maya though, only xsi and max.