tiled exr slows/crashes render when used in displacement

[gardeler]

I was comparing render speeds by doing tests on tiled exr vs. tiffs. First I was rather disappointed. There was a speed gain, but only from really far away, then moving the camera closer the rendertime of the tiled EXR started to creep up and passing the tiff shaders rendertime. going in on a closeup of the object finally caused maya to crash.

I re opened the file and turned off displacement in renderglobals, and suddenly the performance I was looking for was there.

can anyone try to reproduce this?
my setup is a vray material with 4 different tiff textures in displace, bump, reflection color and diffuse. A copy of that shader only with exr's instead of tiffs.

Thanks

Martin

EDIT: I took this snapshot of my netcard load after doing two renderings. It clearly shows that tiled exr's makes total sense. Nice feature!

[vlado]

Which V-Ray version is this?

Best regards,
Vlado

[mr furious]

I was under the impression that you don't want to tile displacement due to the nature of the multi-resolution and the way it would dynamically load that you might get undesired results in displacement.

??

[gardeler]

@ Vlado we are using Build_13801

@ Mr furious yes, you might be right here. But I still think it should not behave like this. But it might be unimportant if it not desireble to use tiled EXR's for it.

Thanks

Martin

[vlado]

Have you tried increasing the dynamic memory limit? You can also try using a separate texture cache using the VRAY_TEXTURE_CACHE=N environment variable where N is the texture cache size in megabytes. By default V-Ray uses a common memory pool for dynamic geometry and tiled OpenEXR files, which may be a problem if the memory limit is too low.

Best regards,
Vlado

[mr furious]

What does this texture cache do? does it copy locally the textures or is it separate allocation in ram for textures?

[vlado]

It is a RAM cache to store recently used tiles.

Best regards,
Vlado

[gardeler]

Thanks Vlado, I'll test it. I have noticed several places that the answer "upping the dynamic memory limit" pops up as it might be set a little low as default. What would you suggest it to be for a lets say a 12gb system? Or is there a % scale I can use? The reason I ask is that I'm thinking about creating a script that sets things up the way that we like to work, so I don't have to do that manually every time.

Thanks

Marre

[Metzger]

Are your exrs both tiled and mipmapped?

[mr furious]

Vlado,

Do the included image2exr that comes with vraay now do both tiled and mipmapped?

[gardeler]

@Metzger: yes. I used the img2tiledexr program with the -m option as I think you suggested in another thread.

[mr furious]

i don't see -m as an option flag in the help for the img2tiledexr.exe what build are you using?

[gardeler]

i don't see -m as an option flag in the help for the img2tiledexr.exe what build are you using?

Sorry, the -m option is when using exrmaketiled.exe from the openexr webpage. If you use img2tiledexr.exe it should do it by default. ( I tested them both, and I only got it to work with img2tiledexr.exe by some reason. I guess I confused the two. )
Btw. Does anyone know a program that can actually view the different tiles? Right now the only thing I can check is to see if the load time of the bitmaps shrinks when using them...

[vlado]

Do the included image2exr that comes with vraay now do both tiled and mipmapped?

Yes, by default it creates a mip-mapped tiled OpenEXR file. As to how big to set the memory limit, 8 GB might be good for a start.

Best regards,
Vlado

[gardeler]

Is there any way that you I figure out if the exr is mip map tiled, or just regular?

Thanks

Martin