ABSTRACT
Walking the min/max shadow hierarchy does add to the texturing cost. Ideally the texture operations count for quick rejections should be as low as possible. Also min/max shadow maps tend to not always quickly reject pixel blocks for flat features like floor polygons. This is especially true if one pixel in the min/max shadow map maps to a quadrangle of on-screen pixels. To be quickly rejected, one of these on-screen pixels has to either be in front of the minimum depth or behind the maximum depth. Without a big depth bias and all its associated problems
a pixel can usually only be rejected after a deep descent down the min/max hierarchy. This situation is depicted in Figure 2.1.
