I don't know how you intend to get that plot from that data, but maybe your actual data has more resolution.
ZCV=[1 2 1 2;6 5 2 8;3 5 9 4; 11 2 0.5 6]; % yellow surf
ZBTmod=[5 2 9 4;1 2 0.2 9;10 9 5 7; 0.6 5 8.3 4]; % cyan surf
ZCD=[2 8 9 5;1 0.2 5 8;6 2 5 8; 0.6 9 8 7]; % red surf
ZCB=[6 2 6 2;2.3 6 7.3 5;4 4 4 6; 0.1 2 8 6]; % blue surf
% stack the arrays
ZZ = cat(3,ZCV,ZBTmod,ZCD,ZCB);
% find the minimum values and the corresponding source index
[Z idx] = min(ZZ,[],3);
% if all that's desired is a flat-colored image
% then there's no need for surf() or the Z data
% just generate an image from the indices and the colormap
CT = [1 1 0;
0 1 1;
1 0 0;
0 0 1];
outpict = ind2rgb(idx,CT);
% image has the same size as the Z data
imshow(outpict)
