And now, on to issue No. 2, which is subtracting indirect illumination from this footage.

现在，到第二大问题——从镜头中去除间接照明。

Similar comparisons are also made for removing indirect illumination, which is also referred to as color unmixing in the paper.

对间接照明的去除也作了类似的比较，在本论文中称之为颜色分离。

One additional benefit of indirect  illumination and the use of secondary rays is that color can bounce from one object to another.

间接照明和使用二次射线的另一个好处是颜色可以从一个物体反射到另一个物体。

This light is called indirect illumination, and in order to calculate it, we take the  intersection point from the primary ray and generate a secondary ray that bounces off it.

这种光被称为间接照明，为了计算它， 我们取主射线的交点并生成从该点反射的次级射线。