Invalid Framebuffer Errors

[bartolo]

Hi

Right now I'm going through real hell trying to render a rather high resolution image.
The final image is going to be 14k by 5k. The scene is pretty complex in terms of geometry.

Of course I knew from the start that I will not be able to render such a frame whole. Btw... i have ten rendering units at hand. I decided to split it to 3 cameras with matching film-offset. This gave me 3 images 4k by 4k each.
Unfortunately those didn't render at all, breaking with memory errors during the process. Each of the machines has 2 gigs of ram. Though memory usage didn't seem to be too excessive.

Then I proceeded to split those 4k frames in 4 subregions using the -reg commandline option.

Now ... those subregions finish rendering but somehow mental ray cannot save the bloody framebuffer to a file!!! There are completely no errors in all stages of rendering, except ONE which directly follows the line "writing image..." ... and it is:

error 051003: frame buffer 0 invalid, cannot create file (filename follows)

Btw ... I have post-effects and output shaders disabled in the scene. I tried using different output formats to no avail. I tried rendering it on different machines with/without distributed rendering without any success.
Sometimes the images make it to the disk, but most of the time they don't. It happens on a completely random basis.

I have plenty of diskspace, temporary storage, and the scene is pretty clean. There is no animation, no custom shaders, and the shading networks are pretty basic as well. Just phongE materials with textures. The textures are minimal.

This is in maya 6.5

I've been using mental ray since version 1.9 in softimage 3d, then in XSI, now also maya, and I consider myself a rather advanced user, but this is beyond me. I never ever had any problems of this kind in the past.

Thanks in advance for any suggestions.

Ah... and rendering it in standalone is not an option for me. Sorry.

[joojaa]

QUOTE(bartolo @ 04/03/06, 01:49 AM) [snapback]233114[/snapback]
Ah... and rendering it in standalone is not an option for me. Sorry.

Well your probably not in position to say this definetly, sometimes the only way is to do what you cant. THus forcing your hand. THing is tough you could lease the software insetad of buying it, or even lease the entire rendering. But i cant se that much helping your problem, other than making your life easier with the higher memory cap.

But yes it sounds rather wierd that it would render and then not write out. It rather sounds like theres still some memory peaking that does probit it from taking place. But truth is splitting a raytracing render to pieces does not realy help much.

Now the reg command does not realy work to minimize memorey consumption for the framebuffer at all due to the way it works. bacause it does reserve a framebuffer of real size, wich is the problem. So try splitting it to more cameras that might help. Since its tge framebuffer peaking thats failing. Also you could do some manual pruning for each part so the parts that render region a dont include geometry in region C wich you have eyeballed or tipped wont account for much in the image anyway. OR render out parts of it to reflectable imageplanes.

Also try leaving aslpha and zbuffer away form the images?!? if you need thenm render in other passes as this can be enough to tip teh scales in your favour.

then lastly try spitting some of the stuff out as mi and include that mi in the scene. THis renders out in batch form commandline fine but taxes the coneversion much less, also you miight find some things to optimize in the result mi.

now sanity chek for me 15x5k is that a 2,5 * 0,84 m printjob? if it is then you could probably safetly drop the res a bit if its half this then you ABSOLUTELY can afford to drop the resolution to 150 dpi

[bartolo]

Thanks for a prompt reply and all the hints.

This framebuffer dropping is indeed very weird. It seems to be somehow linked to the render time... I.e. the longer the image takes to render, the higher the probability it will fail.

I tried opening the temp framebuffers which mentalray leaves in %TEMP%/fbXXXX using imf_disp. Some of them open up OK though they are visibly lacking a few tiles, while others are just zero data.

Regarding the final resolution ... it actually is a 12 by 4 in ten-scale, and my resolution is as low as it can go.

I'm just wondering why on earth isn't it possible for mentalray to save framebuffers tile-at-a-time, when using the .map format.

sigh

Thanks
b

[pornozvedepo-pornozvedepo]

Thank you for good communication.

dubli