From: Thomas Koninckx <Thomas.K<oninckx@es...>  20021126 15:58:13

Hi, I used PMatrixDec to extract the extrinsic cameraparameters M of a projectionmatrix P. With P[3x4]=K[3x3] x M[4x4] = K x [[R;0 0 0](RT;1)] and K the uppertriangular int. cam. mat. M, internal representation d_matrix, is computed using explicitly the conditions that K is upper triangular and contains a 1 at position (3,3). This worked fine for me if the P matrix was computed by a good (nonlinear) estimation. If I however used a linear least squares estimator for the computation of P (error on backprojection was still quite small) the decomposition resulted in a non orthonormal R inside the external matrix M. If I used PMatrixDecCR, and recomposed M as indicated above, the orthonormality of the Rmatrix was assured by the QRdecomposition that is used inside this class. This solved a least my problem (I only wanted to undo the influence of external cam.params.). Am I making a mistake somewhere... or might it be better to replace the internal computations of PMatrixDec, by an indirect computation based on PMatrixDecCR? Regards Thomas   Thomas Koninckx Katholieke Universiteit Leuven tel.+32(0)1632.10.90 Department Electrical Engineering(ESAT) fax. +32(0)1632.17.23 PSIVISICS (VISion for Industry Communications and Services) Kasteelpark Arenberg 10 tkoninck@... B3001 Leuven Belgium http://www.esat.kuleuven.ac.be/psi  