OK, back to the technical aspects ... some issues of sharing a common server-based image were already discussed in the thread about a changing environment, a landscape eroding by the walking characters, making paths through the grass, and grass growing back over unused paths...
The usual server messages are small. UDP has a limit of less than 64 KB per packet (remember the risk of losing connection to overfilled storage categories?); bigger images would probably require several packets to be sent to fill the file, but UDP is an unreliable kind of connection, the server won't know if packets arrived, they may have to be sent several times to ensure their arrival. This will eat bandwidth a lot, possibly.