Hi, I am using the inverse transpose to transform normal vectors. But suppose D is the inverse transpose of a matrix M and that I am using homogeneous coordinates (w=0 for vectors). When I write D*v, where v = (x,y,z,0)^T (column vector), the w component of the product is not zero if M contained a translation. So it seems that vectors are no longer transforming to vectors. Am I doing something wrong or does the inverse-transpose derivation assume a linear transformation (not affine)?