tiled exr slows/crashes render when used in displacement

[vlado]

Back to the original issue; I could reproduce some problems with tiled OpenEXR files and displacement; looking at this now.

Best regards,
Vlado

[vlado]

You can do it with the exrheader tool from the OpenEXR distribution.

Best regards,
Vlado

[gardeler]

Thanks Vlado!
I also have some bad news regarding the tiled exr's. In my test It reads in faster, but doubbles the rendertime some how. It might be because of the higher bit depth, 8bit tif's vs 16 bit exr's. So I think for this time around I will have to go with the tiffs after all... If I get the time, I will try to dig deeper into what is going on..

[vlado]

Ok then; it would be useful to look at the scene if possible, to check/fix any issues that might be there.

Best regards,
Vlado

[gardeler]

Sorry Vlado, due to a 26 page NDA contract I can't send anything out..
But I can see that my computer is running out of RAM with the full res textures. I think that the exr's are consuming a little more ram than the tiffs due to the bitdepth perhaps. rendering with 1/2 scale textures my computer pulls through without reaching my 12 GB limit. The rendertime difference between tif and EXR is almost nothing then.

Best

Martin

[vlado]

In memory OpenEXR textures are stored as full floating point at the moment, whereas 8-bit TIFF files stay 8-bit when loaded... this could very well be a reason.

Best regards,
Vlado

[Metzger]

You sure you have mipmap turned on in the file read node? Also are you using Light cache at all? I wonder if light cache is loading up the max resolutions of the mipmap for GI calculations. It feels like that when I render Light Cache on. Vlado, what mipmap resolution does Light cache load for GI calculations?

[vlado]

I wonder if light cache is loading up the max resolutions of the mipmap for GI calculations. It feels like that when I render Light Cache on. Vlado, what mipmap resolution does Light cache load for GI calculations?

Now that you mention it, it does look like it uses more detailed mip-map levels than strictly necessary. This should be fixed for revision 14127.

Best regards,
Vlado

[gardeler]

@Metzger: No GI for the scene yet. So it is not that. However I notice a significant load speed increase when using the EXR's. Still the render takes longer. But I do run out of ram when using the 4K textures, both for the tiff' s and the exr's. I guess the exr's being float is eating up more ram than the tiffs. I have ordered another 12 gb ram and will do another test when that arrives. Hopefully 24gb ram should be able to handle the EXR's.

[mr furious]

so "mipmap" needs to be set to on in order for vray to take advantage of the mipmapped file? (just checking since lots is undocumented).

A

[Metzger]

so "mipmap" needs to be set to on in order for vray to take advantage of the mipmapped file? (just checking since lots is undocumented).

A

I did some tests and noticed a difference in mipmap loading times when mipmap was turned on in the file read node. If it was set to off, it would take longer to load meaning it was always loading the highest resolution.

gardeler: Are you running a 360 camera render? I had problems with Vray not loading the correct mipmap resolution because the 360 camera setting would load the highest mipmap at all times. Also, you are saving compressed tiled exrs? I use txmake from Renderman for conversions so I can't vouch for Vlado's converter.. though I do need to try it out eventually.

I have rendered a 32k map in Vray that was tile mipmapped at about 14 seconds a frame in Vray at HD. It was very impressive. Just one super highres camera projection baked to one UV set from Mari.

Also, try setting the global scene rays set to 3. I bet you have something reflecting back and forth where 1 bucket is trying to load all textures for the entire scene. Now if you have a lot of cores, more ram is a must. I recommend 24 gigs of ram at least for city renders with 3 rays. I don't know what you are rendering, but I do hope you find a solution to it..