Velocity Texture / Visualize Velocity

Hi there,

I’m trying to visualize the motion vectors of objects (for use in post production after outputting different buffer passes) - but can’t seem to replicate something similar to the VisualizeTexture in UDK (red/green channel to visualize motion vectors):

https://udn.epicgames.com/Three/MotionBlur.html

Anyone with ideas on how to replicate this?

Thanks!