Free Nuke 6.1 Gizmo: P_Matte Position Pass Mattes (Ivan Busquets)

Overview

Ivan Busquets' P_Matte extracts mattes from images containing position data in any given coordinates, such as a P pass, worldP, position or pRef. It lets you choose between a sphere or a cube-shaped matte, with controls for scaling, rotation and skewing and options to tweak the amount and type of falloff.

One of its main goals is to stay simple and fast for interactive sampling. Nukepedia lists it for Nuke 6.1 or later, and it is free with a Nukepedia account.