Some guys of you may know this lil video from the Truevision3D forums, where I was visualizing the different frustum splits in a tinted way:

The split distances are recalculated very time the maximum frustum depth changes. In other words: The shadow maps cover the whole visible area to push more shadow map texels onto the geometry. This happens when the player looks “outside” the map, that is, when the frustum depth is further away than the worlds boundaries. Note that the near red split disappears for some reason. In addition, the split borders become nearer to the player and when theyre to close to the camera, the borders and mainly the resolution/quality differences are noticeable. To avoid this problem/artefact, I rewrote the split distance calculation. The original code uses logarithmics to adapt the effect of view depth. I ended up with a small addition, which “snaps” the nearest split distance to a static border. The effect is quite nice and offers far better shadows:

So this one has a better split sheme applied to it. Take a look at the near red layer. It will always cover the near area around the player to assume the highest detail - regardless of the maximum frustum size.