A comparative study of stereo, vergence, and focus as depth cues for active vision

The performances of the binocular cues of stereo, vergence, and the monocular cue of focus for range estimation using an active vision system are compared. The performance of each cue is characterized by its sensitivity to errors in the imaging parameters. The effect of random quantization errors is expressed in terms of the standard derivation of the resulting depth error. The effect of systematic calibration errors on estimation using each cue is studied. Performance characterization of each cue is shown to be useful for active control of the imaging parameters to improve the accuracy of the estimated range. Methods to integrate the use of the cues in order to overcome their individual limitations are discussed.>