hehe checked this as first thing before posting
but of course It would be 2 easy If it could work this way I would be stunned and then I would check if I'm still running F&L or some other apps
I'm certain the only way to do it is with Observers...which is not complicated at all. There's a spell in Mazz that makes all enemies visible--it probably relies on Observers, but you could ask ChrisP.
It's in Fear, under the Visibility drop-down menu. But Fury is right, there are only 3 choices - None (a blind unit) Nearsighted (units can't see very far) and Farsighted (farther than Nearsighted but still not very far).
in monster flags you can set a unit to 'not respect visibility' which means it will be seen from anywhere(for example the winch in Into The Breach) So you could set all units on your maps with this flag and then you have visibility of everyone!
Ah Ha. Yea that's probably the flag I was thinking of. Still not exactly what you want though
Set up a bunch of observers with Far and Extended flags set on them. Wont need too many. A submesh is 32x32 world units, and with extended as CP described, you get 38 all the way around the center of the unit. If you placed a unit where 4 submeshes meet in the center, you'd effectively be able to view those 4 submeshes with 1 observer
256 pixles to a submesh... you can do the math depending on how large your colourmap is, on how many observers you'll need.
If it could work this way I would be stunned and then I would check if I'm still running F&L or some other apps 
