Good stuff,
I used to play an online version of
"Where's Wally/ (Waldo to our American cousins)" with friends in the states. We'd take or have photo's taken of ourselves hiding in various environments and the others would have to spot them. (May be good to start it again).
As I've said in other threads different camouflage worked well in different environments and sometimes could work badly against you. I found that American "Tiger Stripe" worked better than trad old British camouflage generally in UK mixed woodland as it tended to break up your outline better. For multi terrain and open ground I found German Flecktarn pretty hard to beat and the clothing was cheap and well made.
My tweed shooting outfit (for posh days) was an autumnal brown and on the moor you just disappeared in it and indeed some odd colours work quite well, I had a woollen jumper that was mainly dull purples and browns (sound bad but I liked it) and the amount of times I almost lost the darn thing as it disappeared in mountain moraines. And I looked like a floating head in many photographs.
Hiding from mammals and modern military optics can be harder as they "see" into different light spectrums than we do. Why all my shooting clothing is never washed in standard detergents. They have UV brighteners which give the game away too easily. Some modern sniper outfits in development also have been made to hide body heat as potential enemy are increasingly using thermal imaging.
Outline and movement give the game away but also odour and animals can point you out. Hiding in obvious places too is dumb. I often worried that the locals may think I up to no good when out with the dog as I tend to be quite quiet and like to watch the local animal wildlife. The amount of times I've had to announce my presence to other dog walkers as they've not noticed me and I don't want to give them a start.
Some of the animal camouflage is quite stunning especially insect life though my fave pic is one of an owl hiding in a tree...
You can see it due to the closeness and the eyes but I just love it.