I think this is from the back of Physically Based Rendering[0] by Pharr, Humphreys, and Jakob (3rd ed). The book is also available online[1]. [0]: https://www.

I think this is from the back of Physically Based Rendering[0] by Pharr, Humphreys, and Jakob (3rd ed). The book is also available online[1]. [0]: https://www.pbrt.org/ https://www.pbrt.org/ [1]: http://www.pbr-book.org/ http://www.pbr-book.org/