Graphics Programs Reference
In-Depth Information
Attribute Editor), Maya generates shadow maps
that locate where shadows fall by following the path
of the light backward from the lighted object to the
light itself. Shadow maps create fast, fairly accurate
shadows through Maya's renderer. See the next sec-
tion on how to create shadow map shadows.
The second method for casting shadows is
achieved by raytracing with Maya's software ren-
derer.
Raytracing
involves tracing a ray of light from
every light source in all directions and tracing the
reflection to the camera lens. Therefore, you can
create more accurate shadows with raytracing.
However, this render can take longer to calculate,
particularly when using soft shadows. Later in this
chapter, you'll learn how to create raytraced as well
as soft shadows.
You need to turn on raytraced shadows for each
light when you want more accurate shadows: either
soft and diffused or sharp and crisp-edged, as well
as enabling raytracing in the Render Settings win-
dow. See Figures 10.25 and 10.26.
Figure 10.25
A Directional light with Depth Map shadows renders faster and is
usually detailed enough.
Shadow Map Shadows
For every light type except Ambient, you can turn
on shadow maps through the light type's Attribute
Editor, as shown in Figure 10.27.
The depth-map Resolution defaults at 512. The
higher this resolution, the better defined the shad-
ows. Figure 10.25 was rendered with a depth map
Resolution of 4096, a very high value. Figure 10.28
is the same render with a depth map Resolution
of 768. Most shadows are detailed enough with a
depth map Resolution of 1024.
Figure 10.26
A Directional light with raytraced shadows produces more detailed
shadows but sometimes renders more slowly.
Directional lights aren't the best lights to use for detailed shadow-map shadows
because they require a high resolution for the maps; however, their raytraced shadows are
extremely well done, as shown in Figure 10.26.
Spot lights create shadow maps with greater accuracy at lower depth-map Resolution set-
tings and faster render times. As such, Spots are preferred to Directionals for shadow-cast-
ing lights. Figure 10.29 shows the same render with a Spot light and a depth map Resolution
setting of only 1024, one-fourth the size of the Directional light's depth-map Resolution.
