Texture and Light for Architectural Exteriors - 3D for Graphic Designers - page 411

This will randomly assign a value from somewhere in the gradient to each individual blade of grass, as
shown in Figure 11-27 . This method of colorizing the grass gives you exact control over the range of colors
in the material but no control over the position of these colors.
To gain more control over the coloration, image maps can be useful. Any image can be applied to the
Diffuse Color channel to add color to the grass. In addition, the Diffuse Amount can be altered in the same
way. A photograph of grass can make an excellent start because the particles can derive their color from the
color in a real-world sample. If the colors in the photo do not match exactly with your designs, a process
layer can be used to alter Hue, Saturation, and Brightness of the image, and as a result, the grass blades. Fig-
ure 11-28 shows the grass with an image of grass (from the preset modo content) used as the Diffuse Color
and a process layer used to add some additional saturation and darken the colors slightly.
Figure 11-27: A gradient set to Particle ID randomly controls the color of each blade.
Figure 11-28: Grass colors based on a photograph that has been slightly altered via a process layer