Next, you’ll paint a bump pattern on Dino. In Maya, a bump texture creates the illusion of surface relief. It does this by perturbing the surface normals to make the surface appear bumpy. This is useful for making Dino’s skin appear more “reptile-like”.
Earlier in the lesson, your painting affected only the Color attribute. To paint bumps, it’s necessary to select a BumpMap as the new attribute you want to paint, and then assign a new texture for the bumps you’ll create.
In the scene view, Dino’s color changes to white. Bump map textures are based on grayscale colors. By default, when you create a rendered image, bumps will appear in the areas of the surface where there is significant grayscale color contrast. For instance, if a region has black and white stripes, you’ll see grooves there. Regions with little or no contrast display no bump.
The bumps will not show in the scene view (unless the scene view is set to High Quality); you must create a rendered image in order to see them. The same is true when you paint certain other attributes, such as Transparency and Incandescence.
The bumps appear as grooves in Dino’s surface because you painted contrasting black stripes on the white texture. In general, gray or black over a white background results in bumps that appear indented.
If you wanted bumps that appear raised on the surface, you could start with a black background and paint gray or white over it. For example, you could flood the texture with a black Flood Color, then paint white or gray strokes rather than the default black.
Greater contrast between the background color and the color you paint results in deeper-looking bumps. Less contrast results in more subtle bumps. In the previous step, you painted using a black color, resulting in prominent bumps. If you change the Color setting to a light gray and paint on the white background, only subtle bumps will appear.