Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: snakebox on 2014-09-23, 10:30:10

Title: No GI render element ?
Post by: snakebox on 2014-09-23, 10:30:10

I know this has been brought up a few times (when I use search) but I haven't found any actual answers yet.

So is it currently possible to render out the elements needed to fully composite an image? coming from Vray I would expect some sort of direct light and GI element but I can't seem to get my head around this currently?

I might just be totally blind or missing something but it feels like all I can get out is reflection, refraction and direct light... no the GI ?

Thanks guys! 

(see corona is so awesome that I haven't really needed to break up my renders yet :P )

EDIT: aaand I just found the Indirect pass... my bad!

Title: Re: No GI render element ?
Post by: Ludvik Koutny on 2014-09-23, 11:06:36

There is a bunch of elements at the top starting with CESSENTIAL. If you add all of these and combine them all using ADD operation in post, you should get exactly 1:1 same output as your beauty pass. But only if you keep your output linear (do not use highlight compression in color mapping settings).

Title: Re: No GI render element ?
Post by: snakebox on 2014-09-24, 01:57:30

Ooooh...  no highlight compression.... Hmm :P  but that's the coolest thing about corona! haha

Title: Re: No GI render element ?
Post by: Ludvik Koutny on 2014-09-24, 09:57:09

Quote from: snakebox on 2014-09-24, 01:57:30

Ooooh...  no highlight compression.... Hmm :P  but that's the coolest thing about corona! haha

Yes, it is, but in Vray, Reinhard color mapping for example also breaks element compositing. HL compression is just non linear operation, so it does not add up correctly. You can always simply disable HL compression before final rendering, compose layers in post, and tone map it in post after layers are composed.

Title: Re: No GI render element ?
Post by: johan belmans on 2014-09-24, 12:10:27

Hi Rawalanche


two questions:
-disabeling HL compression=  set the value to 0 or 1?
-Has Exposure, contrast and white balance influence aswell?

edit: typo

Title: Re: No GI render element ?
Post by: Ludvik Koutny on 2014-09-24, 12:17:11

About HL compression. Keep it at default. I think default is 1. That means linear.

As for the other question. I am not sure. Keymaster will know. :)

Title: Re: No GI render element ?
Post by: Ondra on 2014-09-24, 13:57:46

contrast, gamma (other than default), and highlight compression are only nonlinear parameters

Title: Re: No GI render element ?
Post by: johan belmans on 2014-09-24, 14:05:13

OK many thanks

Title: Re: No GI render element ?
Post by: johan belmans on 2014-09-25, 09:46:27

Keymaster

I left contrast, gamma and HL compression at 1.
Saved out as a 1 EXR (16 bit) with all the Cessential passes included.
In After Effects (linear workflow) opened the EXR and extracted all the different pases.
When ever I put the beauty pass on top of the extracted pases there is a difference in, I think, translucency.

Am I doing something wrong?

Title: Re: No GI render element ?
Post by: Captain Obvious on 2014-09-25, 11:33:31

Could you post the OpenEXR file(s)? I can check in Nuke to see if it's a problem in AE or with the render elements.

Title: Re: No GI render element ?
Post by: johan belmans on 2014-09-25, 11:47:53

OK no problem

By the way I now it is huge, but I have a backplate shot with a Nikon D800......

here is the link to download the EXR

http://we.tl/STb1EK8kku (http://we.tl/STb1EK8kku)

Title: Re: No GI render element ?
Post by: Captain Obvious on 2014-09-25, 14:31:47

239 megabytes? Crikey.


Looks like it's AdobeMath(tm) at work. Looks fine in Nuke, aside from a small fringing. Not sure why there would be fringing.


The attached images show the result from adding together all the render elements. The "difference" one shows the difference between the result and the main output, while the other one shows the comped and the main output spliced together in a checkerboard pattern. You can't really see which is which.

Title: Re: No GI render element ?
Post by: johan belmans on 2014-09-25, 14:36:29

OK so it is After Effects.............:-


Thanks Captain

Title: Re: No GI render element ?
Post by: Captain Obvious on 2014-09-25, 14:37:42

This is really weird. I have *no* idea what could be wrong in After Effects. My first thought was that it was treating everything as sRGB but "linearizing" with gamma 2.2, which causes a discprepancy in dark colours, but when I adjusted for that in Nuke, it made for a much much bigger difference. It's really just the foliage that's different between your images, and any kind of incorrect colour math produces a massive difference everywhere.


Frankly, just buy Nuke or Fusion. Or dig out an old Mac and look for a copy of Shake. Almost anything is better than After Effects for comping.

Title: Re: No GI render element ?
Post by: johan belmans on 2014-09-26, 10:25:03

Ok I just found the poblem.

Apparently the opacity of my translucency layer was 50% 8-/

Thanks for the efforts, at least now I know I do not have to buy Nuke :-)

Title: Re: No GI render element ?
Post by: Captain Obvious on 2014-09-26, 19:05:02

Ooops :-)