3DMax多通道渲染技术

Final Product What You'll Be Creating

wice a month we revisit some of our reader’s favorite posts from throughout the history of Cgtuts+. Today we’re taking a look back at Ahmed Fathi’s tutorial on compositing Vray render layers in Photoshop. This tutorial was originally published back in July of 2010, and generated

a lot of interest. So if you missed it the first time, why not check it out now.

In this tutorial Ahmed Fathi takes a look at how to composite together V-ray render layers using blending-modes and masks in Photoshop. Once completed, this process allows you to change or tweak any aspect of your image in seconds without having to re-render a thing! Ahmed also covers a few extra post production techniques such as Chromatic Aberration and Depth Of Field, as well as how to emulate a Cross-processed look.

Step 1

As this is a compositing tutorial, not a lighting/rendering tutorial, I’ll assume that you have at least a basic knowledge of V-ray, and that you are able to render out your own scenes already. We’re going jump straight ahead into setting up the different render elements for the compositing process.

In order to make V-ray render out the different layers, we first have to enable them in the V-ray Render Elements tab within the Render Settings window. Once in the tab, we want to enable the following render elements as shown :

•VrayDiffuseFilter

•VrayMtlID

•VrayObjectID

•VrayRawGlobalIllumination

•VrayRawLighting

•VrayRawShadow

•VrayReflection

•VrayRefraction

•VraySpecular

•and VrayZDepth.

Most of these elements don’t need much work to get them right, but we are going to need to take a few steps to set up the VrayMtlID, VrayObjectID and VrayZDepth layers.

Step 2

We’ll start with the VRayZDepth element. The ZDepth layer is a black and white map that is used to tell Photoshop how far each object in our scene sits away from the render camera – the further the object is from the camera, the darker it will appear in the Zdepth layer. Typically the Min value is used to tell the compositor which objects will be in focus.

In order to correctly setup a Zdepth map, we have to adjust the Min & Max distances that V-ray should calculate, and therefore what appears as white (the Min value) and black (the Max value) within our scene. Select

the VRayZDepth item in the eleme nts list. At the bottom you’ll see the zdepth min and zdepth max values we need to adjust.

Step 3

To get a sense of what values you should use for the min and max values, you should use a tape helper object to measure the distance between the camera and your closest and furthest objects.

To simplify things, let’s say sphere #2 in the image below is the closest sphere we want to be in focus, whilst Sphere #6 should be slightly out of focus. We would use two tapes to measure those distances and put them in as your Min & Max Values.