A method for mapping a sensor pixel array to an illumination pixel array according to a surface forms a group mapping by assigning each pixel to a corresponding group, each group with p adjacent pixels on the illumination array and each ordered set having k groups, by projecting and recording a sequence of group index images. Each group index image has, in at least two of the groups, no illuminated pixels and in fewer than (k−1) groups, from 2 to (p−1) adjacent illuminated pixels. The sequence of group index images uses pixels from each of the k groups. At least p multiline images are projected and recorded, wherein each multiline image projects a line within each group. Lines in the multiline images are correlated according to the group mapping and the correlation stored in memory. Integers k and p are greater than or equal to 3.