Vray vs. Maya software RAM usage

[Seraph135]

I have some pretty heavy scenes that I'm trying to optimize and so I was starting to look into instancing as a way to cut down on RAM usage, as well as, file size and load times. I come from a long time 3dsMax background and was expecting maya's instancing to behave in a similar way. What I found has me a bit surprised.

In max if I take a single complex object and make 60 copies of it, I can watch the ram usage go up using task manager. Then at render time the ram goes up a bit more which is to be expected as it loads textures and such. If I do the same exact thing only with instances then the ram usage is far less both before and during render time. Both files sizes are roughly the same size though. I had to do this test with the scanline renderer because I don't have vray installed for max at work. So my testing may be somewhat flawed.

In Maya, however, I'm finding something very different. If I do the same test. Then the file sizes are very different with instances being a much smaller file than the copies, and the scene takes a lot less time to prepare before rendering. However, the RAM usage is pretty much the same if using copies or instances. (rendering with Vray). If I switch over to Maya software renderer then the RAM usage is about half of what it is with Vray, but again it doesn't seem to show much difference between copies or instances.

So my questions are....

1) Why is Vray using nearly twice the RAM than Maya software? All the geo is the same, textures are the just grey blinn and the light is just a direct light with shadows on.

2) Am I doing something wrong? Is there a checkbox I'm missing?

3) Is it just Maya's nature that I will far more quickly run up against a memory limit than if using Max? Since Maya doesn't seem to care RAM wise if something is instanced or not then I may only get 100 objects (for example) to render before I run out or RAM where in max I could render many thousands of that same object. I know I could use vrproxies/dynamic memory to render many thousands in maya, but I'm just looking into the behavior of maya and max out of the box so to speak. Not looking to start a "which is the better software" battle here so lets not go there please.

4) Does anyone have any tips for cutting down ram usage in Maya without using vray proxies?

Thanks!!

Tim J


BTW I'm using vray version 2.0.17 and Maya 2012 x64

[ivaylo.ivanov]

I think the only way to go are proxies, but Vlado may tell you more.

[paulDryzen]

Heya,

hope this helps.

1. During rendering VRay needs to put everything from Maya into his own file format, thats why it is using more ram than Maya.
2. Nope seems right to me.
3. Maya doesn´t like showing up geometry in the viewport. It can handle a lot but I try to make everythign invisible or shown as bounding boxes etc.
4. Use proxies for everything you can. Saves ram, saves diskspace, saves exporttime, renders faster (sometimes not). Easy to automate an script etc.

Let me know if you need some more information.


Cheers Paul

[t.petrov]

2) Am I doing something wrong? Is there a checkbox I'm missing?

Can you try to set the option "Render Settings -> Settings -> System -> Default Geometry" to Dynamic and see if there is a difference in the memory usage?

[Seraph135]

Thanks everyone. I need to do a little more testing to confirm this...but it appears my tests were flawed in an unexpected way. I had tested this using a model I didn't create. When I got unexpected results I tested with a different model (which I also didn't create) and finally I tried a third model (again didn't create). The first two models had this strange ram issue but the third did not. After further investigation it turns out that one object in both of the first two models had Vray subdivisions on it. Once I removed them the ram usage dropped down and was behaving as I expected. So it looks to be a non-issue. Although it doesn't explain why maya software renderer was showing no difference in ram usage.

Tim J

[vlado]

I believe the Maya software renderer is a z-buffer renderer (or similar technology); if you don't use raytracing it will take very little memory.

In V-Ray, render-time subdivision surfaces (as well as displaced surfaces) are always re-tessellated, even if the geometry is instanced - typically because the view-dependent subdivision is potentially different for each instance. In these cases, smoothing the meshes in Maya might work better.

Best regards,
Vlado