Lighting Properties
To view and edit lighting properties for the surface data map, surface grid map, surface function map, 3D bubble plots, 3D pie charts, and 3D doughnut plots, first select the plot or map. Then click the Plot tab in the Property Manager. You can then set the lighting type; horizontal and vertical angles; ambient, diffuse, and specular colors; and surface shininess.
Lighting
Click the text next to Lighting to modify the lighting properties. There are three lighting options: None, Smooth, and Flat. None disables all lighting effects. The color shown is from the surface material color only. Each grid cell is divided into two triangular polygons. With Smooth lighting, Gouraud shading is used to interpolate colors within the triangles from the three vertices of each triangle. This results in smooth transitions across the triangles and the entire grid, but it is slightly slower than flat shading. With Flat lighting, only one vertex (grid node) is used to define the shaded color for the entire polygon. Note that each grid cell is divided into two triangular polygons. This results in a faceted look since each triangle is only filled with a single color.
Angles
The Horizontal and Vertical define the angle from which the light is shined onto the surface. These values must be between -360 and 360 degrees.
Colors
There are three different types of light color, Ambient, Diffuse, and Specular. Note that these colors are used to represent reflectivity. White is 100% reflective and reflects the material color unaltered to the viewer. Black is 0% reflective, and causes all material color to be absorbed. Our perception of color is based on reflected and absorbed light. For example, a leaf appears green because it absorbs all colors in the light spectrum EXCEPT green. Since only green is reflected to your eye, the leaf appears green.
Grapher uses a pure white light source. The light "strikes" the surface and some of the light is absorbed based on the color of the surface material at the point the light ray struck it. Some light is reflected to the viewer according to the type of light (Ambient, Diffuse, and Specular), and the reflectivity color associated with each type of light.
Ambient refers to light that has been scattered so evenly by the environment that its direction is impossible to determine. Increasing the ambient light component brightens the scene without casting shadows. The default Ambient color is 90% black which means that the ambient light contribution is fairly small.
Diffuse refers to light coming from a particular direction and is brighter if aimed directly down on a surface than barely glancing off the surface. When diffuse light hits the surface, it is scattered uniformly in all directions so that it appears equally bright no matter where the eye is located. Increasing diffuse light intensifies shadow effects. The default Diffuse color is white, which is the maximum amount of reflectivity.
Specular refers to light coming from a particular direction, and tends to bounce off the surface in a preferred direction. A shiny surface such as metal has a high specular component, while a surface like carpet has almost no specular component. Increasing the percentage of specular light results in strong shadow effects and more pronounced "shiny" or glare spots. The default Specular color is 90% black.
In general, these reflectivity colors should be specified as shades of gray in order to evenly reflect the surface material color components. However, special effects are possible by specifying non-gray colors for the reflectivity. For example, assume the Ambient reflectivity is set to pure red, and the Diffuse and Specular components are set to pure black. The Diffuse and Specular components are essentially disabled by setting their reflectivity color to black. The only light that is reflected to the viewer is red ambient light. Portions of the surface that lack a red component in the material color will appear black, since only red light is reflected to the viewer.
To change the Ambient, Diffuse,
or Specular color, click the
existing color sample to open the color
palette. Click on a color in the palette to use it for the selected
color. Click the 
button to the right of the color
sample to open the Colors dialog,
setting a custom color.
Shininess
Shininess controls the size of the specular reflections. As the shininess increases, the reflections become more focused. Select a value between 1 and 128.