The reason for this is in the article: > The reason for this bunching up of values near 1.0 is down to the non linear perspective divide. The function in ques

The reason for this is in the article: > The reason for this bunching up of values near 1.0 is down to the non linear perspective divide. The function in question is nonlinear. So using "normal" z, values in the range [0, 0.5] are going to be very, very close to the camera. The vast majority of things aren't going to be that close to the camera. Most typical distances are going to be in the [0.5, 1] range. Hence, reversing that gives you more precision where it matters.