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mastajappa
07-23-2007, 02:31 PM
When I render a object buffer into OpenEXR the nice black and white alpha gets an artifact like the attachement http://forums.cgsociety.org/attachment.php?attachmentid=116194&stc=1 But when it renders its perfect in the picture viewer. I do use compression in the options so I think there is lead but maybe I am doing something wrong?

Sorry for the messy post but safari is all i got here and it sucks.

marcorabellini
07-23-2007, 08:29 PM
I think there was a thread a while back about OpenEXR. I too have found that it can leave a little, undesirable edge, even with a straight alpha. I think the work-around was double the render size and scale down, which isn't exactly great but it can work in some cases.
Do a search in here for EXR. There's also some good articles on using it in After Effects, although you didn't say where you were using it; might apply to Photoshop as well. Do a search on the net as well for that stuff. Might also be in the AE forum.
m

mastajappa
07-23-2007, 09:11 PM
I think there was a thread a while back about OpenEXR. I too have found that it can leave a little, undesirable edge, even with a straight alpha. I think the work-around was double the render size and scale down, which isn't exactly great but it can work in some cases.
Do a search in here for EXR. There's also some good articles on using it in After Effects, although you didn't say where you were using it; might apply to Photoshop as well. Do a search on the net as well for that stuff. Might also be in the AE forum.
m

Well its not only the edge but the whole color is wrong it should be 100% white, its an object buffer to use it as an luminance alpha in AE. I suspect it should have something to do with the compression cause it seems to render it well. I'll give it another try without compression but then the dataload will be huge so I hope there is an answer. Thanks for your reply will search the forum a bit.

Mylenium
07-24-2007, 09:15 AM
Well its not only the edge but the whole color is wrong it should be 100% white, its an object buffer to use it as an luminance alpha in AE. I suspect it should have something to do with the compression cause it seems to render it well. I'll give it another try without compression but then the dataload will be huge so I hope there is an answer. Thanks for your reply will search the forum a bit.

Why evenb bother to render an object buffer as EXR (considering that C4D doesn't generate multichannel EXR). I recommend you try the alternative EXR tools for AE from FNord ( http://www.fnordware.com/OpenEXR ), it behaves much better than the default EXR loader for AE.

Mylenium

C.Smith
07-24-2007, 02:13 PM
I thought Maxon was working on OpenEXR fixes or did in 10.111. Not sure if this specific thing was addressed. But at any rate, render out your images themselves in OpenEXR, but Object Buffers in 8 or 16 bit non-OpenEXR. You aren't losing anything. They are simply defining areas for composites and the floating point nature of OpenEXR is useless to it.

govinda
07-24-2007, 05:50 PM
Well, these aren't answers, but I agree with Mylenium and Chris and add my own spin to the ball: EXR files are really big for what they give you out of C4D. Seriously big, hard drive space-killing big.

I can understand this being no solace for a purist and no solution for the problem shown, but for now I think another image file type is a better bet. Until Maxon, busy with a million other things using less staff than other app dev teams, lets us use EXR's multichannel-ality, it looks like there's no upside to using the format and now two downsides.

Simon Wicker
07-24-2007, 09:38 PM
it looks like there's no upside to using the format and now two downsides.

well the up-side is if you need to work in a film pipeline based around .exr then you can.

we just need maxon to beef up the support. also people need to make sure they use the correct compression to get the best file sizes (piz v.s. zip).

cheers, simon w.

Mylenium
07-25-2007, 05:42 AM
...lets us use EXR's multichannel-ality, it looks like there's no upside to using the format and now two downsides.

Yepp, without multichannel support it's pretty useless but to use it to the fullest, Maxon would have to beef up multichannel/ multibuffer rendering in general.

Mylenium

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