1. A calibration unit for an active triangulation setup, comprising: a memory configured to store an image of a reflected portion of a projected structured light pattern that is comprised of a repeating structure of a plurality of unique feature types; the memory unit is further configured to store locations on an image plane of a plurality of distinguishable epipolar lines that are associated with a respective plurality feature types from the plurality of unique feature types, and locations on the image plane of epipolar lines which are associated with an appearance in the image of a respective plurality of markers which are included in the projected structured light pattern, wherein an epipolar distance between any two epipolar lines which are associated with an appearance in the image of any two respective markers from said plurality of markers is greater than a distance between any two distinguishable epipolar lines; and a processor that is configured to determine an epipolar field for the active triangulation setup according to locations of the markers in the image and locations of matching markers in the projected structured light pattern.