Application of Least-Squares Adjustment Technique to Geometric Camera Calibration and Photogrammetric Flow Visualization
Fang-Jenq Chen · NASA Technical Reports Server (NASA) · 1997
Flow visualization produces data in the form of two-dimensional images. If the optical components of a camera system are perfect, the transformation equations between the two-dimensional image and the three-dimensional object space are linear and easy to solve. However, real camera lenses introduce nonlinear distortions that affect the accuracy of transformation unless proper corrections are applied. An iterative least-squares adjustment algorithm is developed to solve the nonlinear transformation equations incorporated with distortion corrections. Experimental applications demonstrate that a relative precision on the order of 40,000 is achievable without tedious laboratory calibrations of the camera. 1. INTRODUCTION The photogrammetric technique was originally developed to determine topography using aerial photography with ÒmetricÓ cameras. Due to the advent of CCD (Charge-Couple Device) digital cameras, non-topographic applications of photogrammetry especially in the field of close-r...