Current camouflage patterns are not only expected to be difficult to detect by the unaided human eye but must also be difficult to detect by various electronic vision enhancement devices.
*Night Vision Device comparison photos of US4CES and some of the U.S. Army Phase IV camouflage patterns *
http://www.hyperstealth.com/GenIII-NVG/index.html
*So the Answer to Why not just use MARPAT (Marine Pattern) is multiple.
A) While very effective in the visual spectrum, there is much room for improvement in the NIR (Near Infrared) and SWIR (Short Wave Infrared) spectrums where even the failed UCP (Universal Camouflage Pattern) performs better than MARPAT Woodland in the NIR.
B) The Green and Coyote colors in MARPAT Woodland combine into one color with no contrast between the two into both the NIR and SWIR spectrums.
C) The Canadians found an increase in the Macropattern (large Blobs) for Arid/Desert increased overall effectiveness and that a different color palette was more effective than what they used for their Desert Trial pattern (what would essentially become Desert MARPAT).
As CADPAT TW (Canadian Disruptive Pattern) was designed for both Visual and NIR, we can safely assume that CADPAT AR was also designed with both visual and NIR and our internal tests on CADPAT AR show it to be very effective within the NIR spectrum. The color change with AOR1 from Desert MARPAT did adjust some of this into the CADPAT AR color range.
D) AOR1 and AOR2 outperformed Desert MARPAT and Woodland MARPAT in the U.S. Army’s 2009 study.
Then the question becomes “Why not just use AOR1 and AOR2?”
E) See answers A and B regarding the NIR and SWIR issues and color separation requirement.
Can’t they just apply a coating the uniform to make it match the background reflectance in the NIR and SWIR?
F) This adds cost to the fabric and in some cases it works until washed, then you have a uniform that is worse in the NIR then it would have been had the NIR coating not been applied in the first place, (I won’t name which country this occurred to). It is always best to keep it simple and use a set of colors (with the proper inks) which will get you close before having to turn to additives and coatings*.
http://www.hyperstealth.com/coyote/index.html