uvmapping

Thank you very much for your much helpfull advices! If I may -another question- Is it possible to do retopology with the original texture of the model so it stays on the model while retopologing andis it possible to unwrap it?

Hello, I'm new to 3d coat and i've been doing some retopology to my head mesh which i've imported from my scanner. while doing the retopology I used the symetry option and when i've unwrapped it it was just half of the face and when I tried to export it to blender it was the same. what should i do in order to get a full head unwraped either in 3d coat or blender? does it have to do with using symetry? if it does how can i avoid it and still not retopology the all mesh by hand? would appreciate any advice . Thank you.