Possible Issues

Possible issues that can occur with Projected Shadows Maps .

Blur Color Bleeding

Blur can give flaws in the blend between a shaded pixel and one not.

The following examples have different blur values. In this example only, the floor receives shade.

Bad Self Projection

The parallel piped projects the shadow by itself. The color should be gray, and not pink.

No Z-Checks

Being a simple projection, there is no control on the z, so the parallel piped behind takes the shadow as if the parallel piped in front was not there.

This is also due to the fact that not all objects are casting shadow. Otherwise, the parallel piped behind would be in complete shadow and would not present this defect.

Back face projection

Some faces take shade even if they should not.

This configuration eliminates the defect in most cases; however, it can be slow.

<A HREF="Engine_Graphics_DOF_HDR_B.htm#backFaceRemoval"> this </A> in the DOF HDR B

If everything is cast and receiving shadow, the floor would be in complete shade and the defect would not exist.

If you do not pay attention to manage the lights (parameters and ranges) and objects that cast shadows, hundreds of shadow textures may be generated in a single frame.

Example

In the following example, there are three lights and 20 textures for the shadows.

Note: that Omni alone casts most shadows because it has been set to make an object ShadowMap.