Memory error after 30 frames of animation in MR

[Gwilliam]

This is a copy of the email I sent to Discreet's support team, so apologies for it being so long.

 

I have an architectural flythrough set up with a 5km x 5km ground plane set up and plenty of blocks scattered all over to represent buildings. The ground plane has a 4000x4000 pixel jpg bitmap mapped to it. There is a 5km diameter cylinder with a 8000 x 4000 pixel panoramic sky mapped to it. The building the flythrough focuses on is around 200m x 200m. There is one conform spacewarp to put the road to the ground, and one conform compound object to put the site landscape to the ground plane. There are around 1500 objects in the scene - lots of low poly cars and low poly trees etc. There is plenty of glass in the scene- standard material with raytraced reflection (max reflection and refraction rays:1, total:2) and fresnal falloff, and plenty of bitmaps used, but no particularly complex materials. The are about 170,000 faces in the scene. The units are set to metres. I am using mental ray to render with, using one skylight to provide GI (just to generate GI, not caustics) and one standard omni light to provide raytrace shadows (all GI and Caustics options turned off). I'm using Mental Ray Final Gathering only, with the option to save a FGM file ticked and saved to the hard drive. FG settings:

Min radius: 0.1m,

Max radius: 2.0m,

Samples: 1000

Falloff Limits: 100m

Raytrace settings: Max reflections: 2, Max refractions:2, Sum: 3

 

Receive and generate GI is turned off for all minor objects that won't make a difference.

 

BSP is set to size: 6, Depth: 39

 

Antialiasing samples are min -1, max +1, with box filter.

Jitter is on, Lock samples is off.

Raytrace max reflections: 2, Max refractions: 2, Sum: 3.

 

The scene renders fine for a single frame (the largest I've gone is 2400x1400 pixels and with higher quality settings than those above), but when I come to render the flythough itself, it will render around 20-40 frames in 1-5 hours and then hang with the message:

 

Mental ray has experienced a problem:

mem0.2 Fatal 031006: cannot free memory

 

The flythough is 2200 frames long and is being rendered at 600 x 400 pixels at 25fps to a sequence of .tga files. The only movement in the scene are 10 cars which drive around following path constraints.

 

I have tried changing various options; Bitmap pager on/off, FG rebuild on/off, FG Fast lookup on/off, save fgm file on/off, lower resolution frames, lower FG samples size, Direct X/open GL, larger/smaller/static page file size, different BSP size and depth settings, conserve memory on/off, hyperthreading on/off, smaller/larger render bucket size, collapsing all meshes etc, but nothing seems to make a difference. The time it takes to render a frame may alter with these different options but it still crashes with the same error after a period of between 1 and four hours. A couple of times point it wouldn't even render one frame after being reset after the error, but rendered after I deleted the FGM file which had reached about 100Mb in size.

 

I haven't got a standalone Mental ray license so cannot do distributed bucket rendering. I have tried rendering on two different machines.

 

PC 1:

3.0Ghz Intel P4 with hyperthreading

4Gb Ram, various swap size tried.

Win XP Pro

ATI Radeon 9800 XT 256Mb

P4 Titan 875P GA-8KNXP / GA-81875 Ultra motherboard

 

PC 2

2.4Ghz Intel P4

1.5Gb Ram

Win XP Pro

Nvidia GForce 5200 128Mb

 

3ds max 6 is fully updated with SP1.

 

I would have thought that these machines would easily have enough ram and processing power to do the job. I previously had 3dsmax 5 on the second machine and rendered stills and flythroughs that were much more complicated (1,000,000 faces, 5000 objects) with and without the light tracer and never had any problems.

 

I have spent hours and hours looking for solutions on the internet and help menu but cannot find anyone who's had a similar problem.

 

This is really annoying me (and my boss!), as I cannot leave the machine to render overnight or over weekends without it crashing, so we are losing loads of time. This is driving me mad! Please help!

[K-Mike]

Use backburner and use ur lachine as master and slave. Once max crashes, it reboots automatically at the good frame number, and whith the same settings. If u use radiosity, try to set up for it to save the solution on ur disk at each end frame. I had the same problem, once i found that backburner restars automatically, i was very happy

[Gwilliam]

Thanks for the advice. I spoke to a guy from Discreet a few times this afternoon and he suggested the same thing, but couldn't tell me why it was happening. It's now set up to do about 200 render jobs with just 15 frames a job - and it hasn't crashed yet!

However, Discreet are looking further into it to give a proper solution, or work out whether it's a bug in the program.