Contents
When does projective aliasing occur in a shadow map?
Projective aliasing occurs when the surface normal is orthogonal to the light; these surfaces should be receiving less light based on diffuse lighting equations. Shadow acne (Figure 8), a term synonymous with erroneous self-shadowing, occurs when the shadow map quantizes the depth over an entire texel.
How to improve the depth of Shadow in Photoshop?
In the image at left, the shadow is detached from the object, creating a floating effect. One technique for removing surface acne is to add some value to pixel position in light space; this is called adding a depth offset. Peter Panning results when the depth offset used is too large.
Why are my shadow maps not casting shadows?
Shadow map resolution can also be too high. Although a higher resolution is less noticeable, it nevertheless can result in small objects, such as telephone wires, not casting shadows. Also, having too high of a resolution can cause severe performance issues because of texture access patterns.
How to reduce erroneous self shadowing in Photoshop?
As shown in the left image, some of pixels failed the depth test and created speckled artifacts and moiré patterns. In order to reduce erroneous self-shadowing, the bounds on the near plane and the far plane for the light space view frustum should be calculated as tightly as possible.
Which is the best technique for perspective aliasing?
Cascaded shadow maps (CSMs) are the most popular technique for dealing with perspective aliasing. Although CSMs can be combined with PSMs and LSPSMs, it’s unnecessary. Using CSMs to fix perspective aliasing errors is addressed in the companion article, Cascaded Shadow Maps. Projective aliasing is harder to show than perspective aliasing.
What are some of the issues with shadow mapping?
A standard issue with shadow mapping is aliasing. Projective texturing can result in widely differing shadow map sampling rates across the scene. Raising the shadow map resolution is one solution, but what can we do if we can’t afford the extra memory to do that?
Are there any techniques to improve shadow depth maps?
Perspective shadow maps (PSMs) and light space perspective shadow maps (LSPSMs) attempt to address perspective aliasing by skewing the light’s projection matrix in order to place more texels near the eye where they are needed. Unfortunately, neither technique is able to solve the perspective aliasing.