Hi, I want to know how to transform between image coordinates epipolar image coordinates in DEM extraction. It seems all the parameters need to achieve this purpose are inside the header file, as I attached to the end of this email. but I don't know how to interpret all the parameters inside the header file, such as: adj coef, dlt coef,kx, ky,parallax correction. what's they mean? How can I use these parameters to achieve the transformation? Thank you, Regards, Chris, ------------------attached is a part of the header (.hdr)---------------------- .... right adj coef = { -8.33339849e-002, -2.11964173e-006, 1.09636325e-004, 3.60583429e-001, -5.59314829e-004, -2.58377560e-004} right dlt coef = { 2.03729503e-008, 2.94607864e-007, -9.82331739e-001, 1.91443156e-001, -3.99617180e+001, -1.91292696e-001, -9.81599281e-001, 5.49425364e+001, 1.10580998e-003, 1.10393887e-003, 1.00000110e+000, -3.04537201e-005, 1.63050000e+003, 1.27400000e+003, -1.59563947e+003, -1.89460573e+003} right kx = { 1.16346323e+002, 4.41484629e-008, 5.85755293e-006, -1.61909257e-012} right ky = { 3.99672350e+001, -4.49379668e-006, 4.07896530e-008, -3.91355821e-012} right rpc info = { -3.39600000e+003, 2.13000000e+002, 3.99825000e+001, 1.16347400e+002, .... 1.00000000e+000} parallax correction = { 4.33123082e-001, 1.51167169e-001, 6.08620346e-001, 3.44465673e-001, ...}