对于平行光，Unity可以使用级联阴影贴图(或成为平行分割阴影贴图)有很好的阴影质量，特别是远距离观看。

For Directional lights Unity can use so called Cascaded shadow Maps (alternatively called "Parallel Split shadow Maps") which give very good shadow quality, especially for long viewing distances.

youdao

级联阴影通过分割可视区域逐步部分变大，并使用相同的大小，在每个阴影贴图。

Cascaded shadows work by dividing viewing area into progressively larger portions and using the same size shadow map on each.

youdao