New to ACES, and confused with results! C4D and Arnold

Hi all!

This looks like a place to get an answer or two! I’m new to ACES and trying to understand what I’ve got right and what I’ve got wrong, so I’d like to pose a list of questions…specific to Cinema 4D and Arnold, if anyone can help? Rendering straight from C4D to multipass compositing in AE, but no footage to mix with or whatnot, just CG renders.

  1. What is the correct format for EXR multi-layer files rendered from C4D (using Arnold renderer, but C4D file encoding, not Arnold drivers): I have simply set to OpenEXR 32 bit, with Zip compression in blocks of 16 scanlines, default from C4D.

Now I suspect I should be using uncompressed 16-bit EXR with 16 bit-float checked ‘‘ON’’…
Is this simply a matter of efficiency and disk space utilization? Or is there an impact in colour / luminance etc.? I ran a test, and there seem to be few differences, but the uncompressed 16bit EXR with 16bit float is actually larger than ZIP compressed 32 bit EXR.

Please confirm / deny!

  1. Using ACES OCIO 1.2 delivered a very different looking render than using the default ACES option standard in Arnold 7. Is it best to stay ‘up to date’ with the latest OCIO, or is the implementation in Arnold the best way to access ACES through that renderer? FWIW, the OCIO 1.2 has less saturated colours, seems a little darker than the default ACES in Arnold 7, some lighting differences.

Of course, I had to use ACES 1.2 OCIO as the config file in AE, as I don’t think there is a config file anywhere for the Arnold default implementation.

Or is there? That might explain the big difference in the renders…:thinking:

Is it to be expected that ACES color-conversion makes 'darker’textures, and the answer is more light in the scene?

Many thanks for any clarification.

The most important thing is to use the same OCIO config in all of your software. That insures a consistent viewing environment.

Yes the Arnold and Maya configs are available, and on your machine currently. This is what Maya is reading in the color management prefs. If you do a search on your machine you should be able to find them.

You don’t need 32 bit float, 16 bit half float should be plenty. It is surprising that you were getting the file size discrepancy that you are. One would expect 16 to be smaller than 32.

There is some disagreement as to whether the files need to be uncompressed. I think it is not uncommon in production to use lossless compression.

As far as the color discrepancies this could come from the files being read with aces2065–1 rather than acesCG which is the color space for renders.