Creating a Custom Material in V-Ray
Screenshot
	This workflow explains how to create a custom material in V-Ray with found hi-res images using Texture mapping, as well as Bump and Displacement mapping.
Uses Tool(s)	VRay , Photoshop CS5

Creating a Custom Material in V-Ray

While V-Ray comes with a number of ready-made materials and many more can be found online, often we are unable to find one that is a close enough match for what we are trying to describe. In this case, we will want to create a custom V-Ray material.

Use these files to follow along:
Rendered Room.3dm
Concrete Image.jpg
Concrete Image_bw.jpg

Image Mapping

Sourcing your Texture Map Image

To start, you'll need to make an image to map onto a surface, simply called an "image map". You'll need to find an image of concrete. Not any image, but a nice image for tiling, without overly distinguishing areas that will be noticable in the tiling. These sites have some good selections for various material image maps:

Render Textures

A great collection of texture map ensembles. Each material consists of different matching material maps (such as diffuse, bump, displacement, transparency). This is a good place to go if you want to create your own material from scratch.

CGTextures

Vast library of high-resolution textures for download. Account registration required.

Maya NG's Textures

Over 4250 free, high-resolution textures. Limited to 20 downloads per day.

Preparing your Texture Map Image

As this source image will be tiled to create the material texture, it's best if the image is cropped to remove any distracting characteristics (ie watermarks, etc), as well as formatted to a square.

Your prepared image should look something like this:

Loading your Texture Map Image

Once you have your image, you need to apply it to a material in V-Ray. You do this by opening the V-Ray material editor, right clicking on "Scene Materials", selecting Add Material, and then clicking "Add VRay Mtl". Make sure to rename your new material by giving it a name that matches the material, such as "Concrete".

If you click the grey "Diffuse" layer, you'll notice a small "M". By clicking it, you'll open a new menu box that will allow you to apply your image map. Select "Bitmap" on the left menu and then upload the image and click "Apply". You can update for a preview of the change.

Texture Mapping

In order to add some depth to the material, we can add a bump map or a displacement map. These work like image maps, but add texture instead of an image. You'll need another version of your file that is black and white only, where white represents the part of the image you want to "pop out" slightly. Using Photoshop "desaturate" and "auto contrast" the image you used for the image mapping.

Your image for displacement or bump mapping should look like this:

A big difference between bump maps and displacement maps is that bump maps do not affect shadows, while diplacement maps actually alter the geometry for the render, and therefore affect shadows in the final output.

Bump maps and Displacement maps are set up in the same way. For this workflow, we'll use the Displacement map. Follow the same steps as the Image Map, clicking on the small "m" to add your image as a 'Bitmap', only add the new black and white concrete image as the Bitmap. For materials like brick, concrete, and wood the default 1.0 value for the Displacement and Bump maps is often much too strong and makes the texture very drastic; .25 is a better value to start with.

Transparency Mapping
Though we won't get into it here, there are also Transparency Maps, which you can check out here: Transparency Maps - VRay

Applying and Adjusting your Material

Once you have created your custom material, you can assign it to model geometry as well as adjust its scale and orientation .