And match the lighting across all of the shots, and in order to do that, we simulated the cg world where the lighting was exactly the same, and then we used a number of techniques to copy and mimic what we were seeing in the computer. we still used the photography and built on top of it, rather than replacing it whole hog, but we used the simulation to tell us what that should look like. the director was very keen to give as much of the stuff that he shot as he could. that included the people, that included the buildings the trees, even. but the trees didn t have snow on them, so each tree had to be particularly for the close up trees, they had to be modelled in c6! to look exactly like the trees that were there. we put snow on them digitally and then lifted the digital ....