Colors in the Suburbs map

[kurtosis]

Hello,

I'm a new young scientist player looking for a good way to get rid of the zombie threat. 

My question is about this map :
http://wiki.urbandead.com/index.php/Suburbs

How are the colors updated ? Is it the concatenation of all the local Necronet data ? This would mean that the colors depends on the frequency and accuracy DNA scanners, right ?

Thanks for your answers !
K.