Michael
The original patterns sort of fell out of the sky. The suggestion to camouflage the M113s, I think, came from then Major Jack Vance, the ops officer of 2 RCR. I was the operational kit kid in HQ 4 CIBG and the project landed on my desk. There was considerable experimentation* with all the vehicle fleet, less the Centurions which already were cammed, and by 1968 patterns had developed. I know I spent a few days with the brigade commander observing various patterns in different light and foliage conditions through binoculars from a km or so away.
* The A Battery command post vehicle was painted in an odd and highly effective pattern that many years after the event was revealed to be based on v.gin.s. I am not making this up!