EXTRACTING FOCAL LENGTH USING GEOMETRIC CONSTRAINTS IN TWO UNCALIBRATED IMAGES

There are many parameters involved in obtaining 3D model of an object out of a stereo or multi images. These parameters consists intrinsic and extrinsic parameters of camera. Intrinsic parameters may be classified as coordinate of centre of image and focal length as well as distortion parameters that may be further subdivided into radial and decentering Parameters. Extrinsic parameters also include coordinate of camera and its rotations in a reference coordinate system in which all may be calculated using ground control points (GCP’s). This paper describes a method for extracting focal length of a non-metric digital camera using geometric constraints such as right angles in object space disregarding other intrinsic parameters. Finally, some experiments in reconstruction of 3D model of an object using computed focal lengths presented