Product Render in Layers | Compositing in Photoshop

[Keef86]

Hoping someone can explain how to render out in layers and composite in Photoshop. Part of my job is doing mock-ups and product renders. I have a setup I use that uses a white backdrop with three large rect lights adjusted with temperature, physical camera, and linear workflow.

I've rendered out layers like diffuse, lighting, reflect, refract, shadow, specular, etc and tried compositing using the screen blend mode in Photoshop, but it never comes out like the beauty render. Also, I have no idea what to do with the shadow and matte shadow renders, they look reversed-out and grainy as hell. Would I be better off using a material wrapper for the shadow?

I notice a lot of Vray compositing uses Nuke. Is Photoshop not ideal for compositing rendered layers, or am I just using the wrong render layers and blend modes?

[Neilg]

did you do it like this?
http://cgi.tutsplus.com/articles/com...oshop--cg-4077

[Racso]

Hi, check out this link http://www.stevenolver.com/tutorial-...after-effects/

It's for After Effect but the principle is the same for PS. It explains very well how to composite the render elements, one basic and one advance method.

My experience is that if you render in 32bit the render elements you should do the stacking and assigned correct blend mode in 32 bit mode to get the same result as the beauty. After that's done you can down grade to 16 for easier editing in photoshop.

What I have understood, Photoshop is not handling premultiplied alphas the same way as Nuke or other compositing softwares. This can cause black fringes on the edges and makes comping in Photoshop not optimal. The OpenEXR plugin from fnordware.com does a quite good job when importing multi EXR into PS.

We often use Mtrl Wrapper for shadows which is very handy, so I would recommend that. For even more control in comp you can place the backdrop on a separate render layer within Maya and use VRay object properties to control how objects in the scene effects each other.

Regarding grainy shadows I think you may need to up your subdivs on the lights. A good way to adjust optimize quality is to render elements like RawLight, RawReflection a so on as they better show grain and where it needs to be adjusted. There are some good tutorials out there talking about this.

I hope this shine some light on the issues you have.

/Oscar

[Keef86]

Thanks, all. I tried the cgi.tuts method and it was closer than other attempts, but still didn't get close enough to the beauty render. I'll give this AE tut a try.

Quick question: When I render out, I save the images as targa, which I believe is 32-bit, yes? When I load the layers into photoshop, I do it with the script 'load files into stack'. The bit depth of the resulting stack in photoshop shows as 8-bit. Photoshop will let me change it to 32-bit, but will that make any difference or has the information I need in the renders already been erased?

[Neilg]

.tga is not 32bit - for some reason every other file format refers to 32bit as per channel, and tga's 32bit is 32bit total - which is 8 in red, 8 in green, etc, added up.
its really stupid, but start using exrs and ignore tga. exr gives you 32 in red, 32 in green, etc.

[beenyweenies]

After experimenting with every format available, I've personally settled into 16-bit multichannel EXRs with ZIP compression. It's lossless, so you get the smallest "truly linear" files possible without image degradation. 16-bit gives you almost all of the control of 32-bit in post, without the massive file size. The ZIP compression causes your editing application to slow down a tiny amount to decompress, but the file size savings is worth it.

Multichannel EXR is awesome because all of your render layers are encapsulated in one file.

[Keef86]

I'm having trouble getting the exr to open in layers in psd. In render settings I have 'exr (multichannel)' selected, I save it out from the vray frame buffer as exr, and I've opened the file using both OpenEXR and ProEXR in psd and all I get is a single layer. Any idea what I'm doing wrong?

[Neilg]

I'm not sure if photoshop works with layered exr's - we save every channel as a separate exr.

[Racso]

I have to agree with beenyweenies, multichannel EXR is fantastic!

Layered exr's works fine in Photoshop. Keef86, when you open the layered exr in ps with the ProExr plugin, do you get the ProEXR Import Option box? If not press the shift key when right-click opening an exr file. If not, the plugin may not work. For older versions of PS you need to remove the native ps exr plugin to make the ProEXR to work. in CC you don't need to do that.