BumpCapture

Bump maps are a powerful technique for creating realistically detailed surfaces; unfortunately an artist has limited tools for creating them. Typically he must use 2D image editing software, which doesn't provide all the tools necessary for creating 3D detail.

BumpCapture comes to the rescue by letting the artist use the power of the SoftImage modeler to create his bump map. First the artist models his surface as an actual geometric object, and then uses BumpCapture to transform the geometry into a bump map. Once in this form, the bump map can be manipulated in more traditional ways: distorting the bump map, scaling and mixing several bump maps, creating a tiled bump map, etc.

The image below-right shows the effectiveness of a good bump map. What appears to be a collection of spheres is actually a flat grid. The left image gives the grid its color, the middle image is its bump map - created with BumpCapture, of course.


Procedure

To capture the bump map:

Create the geometry you wish to capture.

Switch from a Perspective view to an Ortho view.

Position the camera to get a mostly straight-on view of the surface.

Set this window to be the rendering window. (Click the window's ID letter in the upper left corner. The window border will turn red.)

In the render dialogue box, select mental ray for the rendering type.

Turn off antialiasing.

Click on Options, and in the options dialogue select BumpCapture as the output shader.

Render.

To capture the color:

Repeat steps 1 through 5 above.

Turn off the BumpCapture shader.

For each object, in the Material dialogue box choose Constant as the shading model.

Render.


Parameters

Channel controls whether the bump-map should be sent to the color (RGB) channels, or to the Alpha channel. In current versions of Mental Ray, sending to the alpha channel can produce incorrect results.