Mental Ray memory problem. please help

[Chats]

Hi there,

I'm having problems rendering a very high res IGES model using Final Gathering that has been imported into Maya from Katia CAD software. If I hide half the objects I can render them, then render the other half separately but that is not appropriate for this project. I need to be able to render the whole model in one pass.
Basically when the RAM usage in the task manager reaches about 2.00 GB it falls over but my machine has 4gb of RAM.

Is there a way to change Mental Ray's max memory usage?
When I render I noticed this line:

MEM 0.0 info : heap size limit set to 800 MB

As in this industry deadlines are approaching fast so any light shed on my problem would be great.
Also I have already overrided all of the NURBS approximation to a very low value which helped alot. Also the amount of final gather rays does not seem to affect the mem usage at all.

Cheers,

[Fugitive]

You can change MR's memory usage from Render Globals>Memory & Performance> Memory limit. Default value is 800 but you can set larger values based on your available Physical RAM like 2000 (2GB)....

Also you may want to consider rendering separate passes e.g. do a Final gather pass and other Raytraced passes (reflection, refraction, shadows etc...) for large memory intensive objects...Try doing a Final gather diagnostics to achieve an optimized Final gather radius value...

BSP diagnostics may also help you come up with a managable BSP setting for your render.

[floze]

Assuming that you're using windows, by adding the /3GB switch to your boot.ini you might raise your crash-limit up to ~2.8GB total virtual memory usage. If you render out in batch mode, another ~500MB to ~1GB might be released, depending on scene. I suggest you to google for the /3GB switch and read through the microsoft help pages before applying it, since it may cause instability.

[carsten]

maya has a field for mental ray's memory limit, but you should know that this limit is for mental ray only. if you set it too high, maya uses a bunch of memory, and then mental ray thinks there is lots more, but runs out prematurely.

to set the value, load your scene, and try rendering out a pass without fg with the maya renderer. note the memory usage. then set mental ray's limit to your_memory - noted_usage. note also that your_memory may not be as much as you have in the machine. windows will often refuse to allocate more than about 1.3 GB per process in my experience. if you have more than this, try setting mental ray's limit to 1.3 GB - noted_usage.

if this doesn't work, export your scene to an mi file and render on the commandline, with no programs running. then you could set mental ray's limit to about 1.2 GB.