Vray multipass probelm...please help

pjbazel

Hello,

Im using vray, and I would like to start exporting multipass layers to composite in PS. I am at my whits end trying to get the passes right.

From what I have seen/read elsewhere I should be able to add {(diffuse x raw GI) + (diffuse x raw lighting) + specular + reflection + refraction + shadow } and get the result that vray outputs in the main (beauty) render.

My problem is that my passes do not appear to be coming out properly. When I composite according to the above formula I get something quite far from the vray beauty/composite pass.

I suspect something is wrong with my vary settings, though I have tried most combinations which seem to make sense in color mapping. For instance when seeing compositing tutorials peoples Raw GI and lighting pass seem to be a grayscale image or have some muted colors, where mine come out black and white. Most time raw GI just has white where my objects are. When i add (diffuse x raw GI) + (diffuse x raw lighting), I can already see it dosent look right.

Can anyone give me some insight into what might be going wrong? It would be much apreciated as I have been toying with this for days now.

Ill attach the images of the passes im exporting, along with my colormapping settings.

Help.Diffuse.jpg

Help.Raw_GI.jpg

Help.Raw_Light.jpg

Help.Raw_Shadow.jpg

Help.Reflection.jpg

$Help.Refraction.jpg$

valerostudio

I have tried to do this as well and the composite does not come out correct. I couldn't tell if it was user error or something wrong with the way the channels are created. I posted this question here and on the Chaos forums with little response. For now, I just save to EXR and use my RGB pass as a base and add in GI, reflections, etc as needed on top of it. Its not true compositing, but it works.

valerostudio

Also, Bright Multiplier needs to be set to 1.0 if using true linear workflow.

pjbazel

Hi Valero,

Thanks for your reply. I am starting to wonder if this is an issue with Vray. I have tried everything I can think of, including almost all possible combinations on the color mapping options. I'm really at a loss.

I don't think this should be a linear workflow issue. Even if the gama was wrong I don't think I would be getting Raw_GI and Raw-Light passes which seem to contain just the wrong information.

I found a number of tutorials on multipass comping, mostly which relate to 3ds max. The passes they get ( specifically Raw_GI and Raw-Light) seem to be quite different from the passes I'm getting. My passes (as shown above) seem to have lots of missing information (again, Raw_GI and Raw-Light) which should multiply into the diffuse pass. The diffuse pass looks like its not the problem.

Ahhhh, very frustrating.

Valero, i'm curious, do your passes seem to be deficient in the same way?

Sorry for the belated response, didn't have internet access over the holidays.

Again any help would be welcome.

panixia

@pjbazel said:

I found a number of tutorials on multipass comping, mostly which relate to 3ds max.
can you link some of them? i'm curious to know more about this.. i mean i must admit i never understood what reflectionn or gi channels are meant to do.. i only know how to use alpha, mat-id and z-depht, but always wondered about the meaning of all those additional channels..

also were i can find a very basic and proper tutorial about "linear workflow"? is that related to color mapping, gamma, etc?? the tutorial i found about this were always aimed to an intermediate level, assuming you know the basics of this workflow and.. i do not

valerostudio

This video says it all. Its incredibly powerful and if you are not saving out GI, Lighting, Reflection and Refraction channels to 32 bit EXR, then you are missing out on a lot. I don't do trying comping like this video but I do render out those channels and overlay them in my post work. The most powerful rendering engine is NOT V-Ray, it's Photoshop!

valerostudio

I've tried to make this work several times with no luck. I asked the same question on the Chaos forums and did not get much back.

http://www.chaosgroup.com/forums/vbulletin/showthread.php?70634-Comping-VFB-Layers

panixia

thank you so much valero! i will give a long hard look at this video as soon as possible..

pjbazel

@panixia said:

@pjbazel said:

I found a number of tutorials on multipass comping, mostly which relate to 3ds max.
can you link some of them? i'm curious to know more about this.. i mean i must admit i never understood what reflectionn or gi channels are meant to do.. i only know how to use alpha, mat-id and z-depht, but always wondered about the meaning of all those additional channels..

also were i can find a very basic and proper tutorial about "linear workflow"? is that related to color mapping, gamma, etc?? the tutorial i found about this were always aimed to an intermediate level, assuming you know the basics of this workflow and.. i do not

Panixia, here are some of the better tutorials and vids Ive found. Valero posted one of them already, and if you look at the layers in that vid you can see how they correspond to the final image RGB. If you look at the layers I posted above in comparison to the RGB they do not seem to have the same kind of information. Thats my problem, Valeros too i believe. If you get to multipass in this way let us know if you have a similar issue.

As for LWF, it seems like it should be simple but I never found a single source which definitively clarified exactly how you should proceed from render settings to PS settings.

Here is a great multipass tutorial with tons of info and he even gives you the layers he's working with to follow along.

http://cg.tutsplus.com/tutorials/chaos-group-vray/compositing-v-ray-render-layers-in-photoshop/

This guys page has tons of great videos, some of wich deal with comping and LWF, for sure book mark that one.