already watch Avatar the making at astro couple days ago....
The navi's are totally CGI
if u watch the making...
they use human muscular face (with dot) to copy face movement in cgi...
thats y we see its so real and this tech quite new...
u can see the different if u watch terminator salvation which they create arnold with funny face..
y happen like that... its because they create...

for avatar.. the computer copy the movement from real actor faces...



p/s : maybe somebody here have best explanation about creating movement in cgi using real person..