View Full Version : Urgent help required - Mental Ray

05 May 2010, 11:42 PM
I'm in the middle of a project that I need to render with mental ray. Everything is working fine, except for one small problem (2 different ones on different computers, actually).

Problem 1: I set a batch render to run, and it completes immediately. In the render log, it says that 'The renderer mental ray is not registered'. Rendering a single frame in the render view works fine, so Maya knows that mental ray is there.

Problem 2: On a different computer, I've tried rendering a different shot using batch render. It renders the first frame fine, but then just hangs on the second frame for ages, and then gives the out of memory error. I've limited mental ray to 512meg in the mentalray default options, and also in the batch render dialog box. The same happens if I try to render from the command line.

I'm in urgent need of a solution to this, so if anybody can help, I'd be very grateful!

System specs:

Computer 1
Windows XP Pro x32

Computer 2
Windows XP Pro

05 May 2010, 01:36 AM
I am no pro at troubleshooting since I am still in the process of elimination mode... but from what I can gather, 512mb of ram for a render doesn't seem much at all... especially if it's a large scene. One cannot simply just limit the amount of ram used and expect mr to complete it with the amount allowed. I would set it to a little below the max amount of ram the computer has in order for it to work properly... even then it might not even work.

A possible reason as to why it's crapping out after the first frame is that it needs to cycle through all the DAG sets (transform data for all object in the scene and consequently memory expensive). If you have a heavy scene with lots of geo, combine some stuff that shares the same shader... or delete what is not being seen. Even then, you might need to break the scene into separate render files. Basically, and this is again if you have a heavy scene, if you have a depth pass, save out the file and delete all the shaders/textures that aren't being used. Same with AO or RGB passes. Just try and cut down the amount that Maya has to think before rendering. It might take time, but it'll definitely save you in the long run.

Also, look into BSP diagnostics... it basically tells you if your geo is sucking too much memory and allows you to trim it down so it can render more efficiently with no loss in data.

I had one project where it rendered about 2 frames and then ran out of memory and it was because of the DAG sets, so perhaps you are having the same problem.

Also, delete non essential history.

There was also a time when we had to bake geo in order to have the file render.

Hope this helps!

Sorry that I do not know a solution to problem #1

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05 May 2010, 01:36 AM
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