Shadow Map Shadows
You can turn on shadow maps for every light type except Ambient through the light type's Attribute Editor, as shown in Figure 10.25.
The depth map Resolution defaults at 512. The higher this resolution, the better defined the shadows will be. Figure 10.23 was rendered with a depth map Resolution of 4096, a very high value. Figure 10.26 is the same render with a depth map Resolution of 768. Most shadows will be detailed enough with a depth map Resolution of 1024.
Now, Directional lights are not 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 10.24 earlier in this chapter.
Spot lights create shadow maps with greater accuracy at lower depth map Resolution settings and faster render times. As such, Spots are preferred to Directionals for shadow-casting lights. Figure 10.27 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.
Trying to squeeze a detailed shadow map from a Directional light with an absurdly high-depth map Resolution setting can even crash your system. In these cases, it is wiser to use a Spot light. If a Spot light cannot be used (for example, when an even Directional light is needed instead), use raytraced shadows.
Figure 10.26
The depth map Resolution setting affects shadow quality for shadow maps.
Figure 10.26
The depth map Resolution setting affects shadow quality for shadow maps.
Figure 10.27
Spot lights cast faster and more detailed shadow map shadows.
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