Camera Calibration

All five cameras were fully calibrated using a moving target with indexed points of known position in 3-space. The target is mounted on a rail with precise positioning device.

The total of seven displacements of the target in the z-direction was sufficient to recover perspective projection matrices and radial distortion coefficients (k1) of all five cameras. The mean calibration error was 0.17 ± 0.09 pixels in b/w cameras and 0.13 ± 0.08 pixels in the color camera. (The error is the magnitude of difference between detected points of the calibration target and the points projected using the recovered camera model and their true 3D coordinates).

Scan Plan

The total of 60 views (one frame is four b/w images and one color image) was acquired and processed. The entire field of view was subdivided into four slightly overlapping segments. In each segment, a landmark was affixed to the wall and used to register the individual partial scans and the four partial reconstructions from different segments. All landmarks were identical and comprised 32 indexed points that were located automatically. Below is a detailed view of landmark A.

Each of the four scene segments was further subdivided into several slightly overlapping partial scan paths (8 in larger segments and 6 in smaller segments). All paths start at the landmark and comprise two to five sligtly overlapping frames each. The camera motion along the partial scan path was calibrated with the help of a registration aid that did not move during the camera view change. One frame before the view change and one frame after the change provided two sets of aid's points reconstructed in 3D space that were sufficient to recover the Euclidean motion of the camera. We therefore did not rely on any prior knowledge of the camera position which allowed us to move the cameras freely around (each motion was limited in extent). A schematic PostScript

Landmark Calibration