Cascaded Shadow Maps
Shadows with more detail near the camera
Also known as: CSM · Shadow cascades · Directional light shadows · Cascade shadow distance · Shadow cascade split
Definition
Cascaded shadow maps are a technique for shadows from a directional light such as the sun. The view is divided into zones, called cascades, from near to far, and each gets its own shadow map, so shadows close to the camera are sharp and distant shadows use lower resolution. The number of cascades and the shadow distance trade quality against performance, and visible lines can appear where one cascade changes to the next.
In production
Set the shadow distance to what the player really sees, increase cascades if shadows look blocky in the middle distance, and soften the blend between cascades to hide the transitions. Unity exposes cascade count and distances in the pipeline asset, and Unreal Engine's dynamic shadows for directional lights use cascades unless Virtual Shadow Maps are used. Distant, static shadows can be baked to save cost.
