max runs out of ram and crashes

[Joel C.]

Hi...

Max 2009 Design SP1, Mental Ray, XP64, 8-gigs RAM, Q6600 Quad-COre (not overclocked)

I have a scene - my Kitchen / Family Room WIP - and when I render at LOW preset values for AA and FG, it renders fine. When I render my AO pass, it renders fine.

When I turn up the presets to HIGH for both FG and AA, Max literally runs out of physical ram and when it hits 8-gigs, it crashes with a Mental Ray error (error unknown, as my PC it locked tight).

I try to use ProMaterials where possible, A&D otherwise, and just one or two BITMAPS for textures.

The scene has almost 2 millions polys and compromises of 5 rooms.

Should I 'turn off' the rooms that are completely out of camera view?

[Travis Schmiesing]

Does it crash while calculating the lighting solution, or after it starts rendering?

What resolution are you rendering at?

What BPS setting are you using, and are you using scanline?

Also, I thought A&D materials were better than Pro-Materials. Am I wrong on this? I heven't used Pro-Materials yet.

Alo, are monitoring the subdivisions on the materials? O opften find downloaded materials are geared towards product visuailization and not tweaked for Architectural Visualziation.

2 million poly's are nothing, that shouldn't be the probelm.

I do not have the answers, but these are quaestions that came to mind on diagnosing your crashing problem.

[Joel C.]

Hey Travis,

Thanks for the reply and some good questions.

max: 3ds max 2009 Design SP1
render engine: mental ray
resolution: 800x600
AA Settings: preset value of HIGH with no custom tweaks
FG Settings: preset value of HIGH with no custom tweaks
Pro-Materials mostly
A&D Materials everywhere else
except
1 texture (my white marble for my kitchen island)
All objects have a UVW Modifier (ProMaterials really likes them, and Mental Ray complains if you do not have a UVW Modifier on some primitives)


problem:
I reboot my computer to have nice, clean memory
I fire up Max and load my scene
At this point, RAM is about 1.2 gigs (as reported by Task Manager)

Max calculates the GI fine
Max calculates the fast lookup table
Max runs through the whole FG stage

At this point, RAM is about 3.5 gigs (as reported by Task Manager)

Max starts to render
It hits about 50% render and the memory usage starts to increase at a pretty good clip.
At this point, RAM is about 4.5 gigs (as reported by Task Manager)

It hits about 60% render and the memory usage starts to increase at a pretty good clip.
At this point, RAM is about 7.5 gigs (as reported by Task Manager)

As you can see, the percentage of render completion increases, it's just increasing faster than my physical RAM.

It hits about 70% render and the memory usage starts to increase at a pretty good clip.
At this point, RAM is about 8.5 gigs (as reported by Task Manager)

I had to leave the computer rendering at this point to go to work, but when I got to work about 30 minutes later, I was unable to connect remotely to my computer. I figure it errored out and locked up.

Not sure what "BPS setting" means...?

I understood that Max 2009 Design really likes ProMaterials.

Not sure what you mean by SubDivisions on the materials...?
I've increased the number of samples to 32 samples to help get rid of noise.


I also noticed that my free space on my boot partition is down to 30 gigs.
(BLOODY IDIOT that built my computer put a 1 terrabyte HD in there, but only gave me 100 gigs for the boot/system files...)

I just wonder if my windows swap file is just swelling up and it's running out of room?

I might try to move my swap file when I get off work today, just to see if that works.


===


Any ideas with this new info?

Just weird how it renders FINE when the AA and FG are set to lower.

[Travis Schmiesing]

Meant BSP not BPS. Samples not SubDivision, I am coming from a Vray background, so tend to use Vray terminology.

So the problem isn't with FG, nor should it be at 800x600. It would be with the AA or Sampling you are using, or the samples being to high on your materials, or a hghl reflective scene.

So next steps...

If you render with high FG, and low AA does it crash?

If you render with high FG, high AA, and a neutral materials override, does it finish?

Others may have a direct answer, I am simply trying to help by narrowing down what is causing the problem.

[Shane Neal]

Probably "BSP" (Binary Space Partition/ing) and considering your problems increase at higher sample rates, I'd say CHG's hit the nail on the head. BSP controls how the renderer divides 3D space into "voxels" at render time, the resulting data being written into a BSP tree which is temporarily stored in memory. The two factors to consider are the BSP's size (how many triangular divisions are in each voxel) and it's depth (how many voxels). The higher the "BSP size", the more memory used. By adjusting the depth and size, you can affect how efficiently mental ray renders the scene.

So, if you're rendering at a low res, the amount of samples needed per voxel is lower and your memory use is lower. As you increase the sample rate and filter size, the renderer will need to look "closer" (AA) and "wider" (filter), if you will, at the geometry and consequently, there will be more stored data. To avoid running out of memory in these cases, reduce the size of the BSP and adjust the depth, forcing the renderer to sample smaller areas more frequently.

From the sounds of things, there's probably a few objects in your scene that are high-detailed meshes/ materials, which would explain why the renderer starts using all the memory about 50 - 70% through the render.

Somewhere in the depths of Max's MR setings, you will be able to render a BSP diagnostic (probably under Raytracing/ Acceleration). I've attached an example of a BSP depth diagnostic (from Maya, but should be the same in Max). It also has a diagram showing how a voxel is divided. Areas in blue/ green are using the least depth in the BSP tree, yellow uses close to the average depth and orange/ red uses the most depth in the tree. Ideally, you want to aim for a good mix of orange to yellow, without getting too much red or blue. Let the diagnostic render times guide you too.

Other things to check - use mipmap filtering on all your file textures, make sure the file textures are only as big as they need to be (no point having a 2048*2048 for a 800*600 render)

[Joel C.]

Travis! Shane! Great stuff!
Thanks for explaining that for me!
I never thought to delve into the diagnostic area.

re: big texture - very good point. I have been rendering A4 size and then reducing in Photoshop so I can control the quality as it resamples and reduces in size. It's not a critical piece of geometry in this particular case, so I can probably cut it in half or 1/4 and not be too worried (after I adjust my real world size, too).

This is going into my notes for sure!

VERY good stuff.

It sounds like I need to reduce my number of samples on my materials...

I'll try this tonight and report back in.

Thanks again VERY much! Both of you.

[william york]

I don't think you need to use a high preset in your FG...that might be overkill, and I have stress tested Max9 64bit on a computer with only 2gigs of physical ram, set my virtual ram to 20gigs...and MR kept taking virtual ram all the way up to like 10gigs as needed without crashing...really really slow cause it was paging from the hard drive, but it never crashed...

[Joel C.]

Thanks William.
Good info there. I'm going to play with my swap file tonight - I think that's part of the problem.

I put a raid 0 controller in the system when I had it built, so hopefully have two controllers reading and writing to the HD will help.

I never saw max use 8 gigs of ram before - it was exciting... until the scene wouldn't render.

I'm very anxious to try this now, but I have two photoshoots after my main job. So still a few hours to go.

Thanks for the info, William.

[Shane Neal]

re: big texture - very good point. I have been rendering A4 size and then reducing in Photoshop so I can control the quality as it resamples and reduces in size. It's not a critical piece of geometry in this particular case, so I can probably cut it in half or 1/4 and not be too worried (after I adjust my real world size, too).

If you're rendering oversize to reduce it in post, then you can render the A4 at lower AA sampling.

[Joel C.]

Wow...

VERY good to know.

Just walked in the door and had locked the PC hard at 68%.

I checked my free space and it was down to 20 gigs on the boot/swap file partition.



I moved the swap file to the d: drive, removed the old one from the c: drive, and it rebooted even quicker than I remember!

I also spent 30 minutes burned junk and crap off the c: drive and got the free space up to 45 gigs. I have had it as high as 70-gigs, so I'll need to review where the drive space is going to (but I'll do it later).

I've put a permanant 20-gig swap on the 900-gig d: drive and it's looking promising.
I've added the "Peak Mem Usage" column to Task Manager, so it'll be like a 'sticky' mark where the mem maxes out. This will let me gauge if 20 is too big or too little.

Firing off a batch of 5 renders now.

I'll post the results in the morning.

Thanks again everyone, some fantastic help has happened here.