Interpolation Technique - Photon Focus MV1-D2048-3D03 Series User Manual

5.2 3D Features

5.2.4 Interpolation Technique

Structured light based systems crucially rely on an accurate determination of the peak position
of the Gaussian shaped laser line. The Peak Detector algorithm in the MV1-D2048-3D03/04
cameras applies nonlinear interpolation techniques, where 64 data points are calculated
between two pixels within the Gaussian shaped laser line. This technique is superior to other
commonly used detection techniques, such as the detection of peak pixel intensity across the
laser line (resulting in pixel accuracy) or the thresholding of the Gaussian and calculation of the
average (resulting in sub pixel accuracy).
The nonlinear interpolation technique used in the Peak Detector algorithm results in a better
estimate of the maximum intensity of the laser line. The data mapping for the 3D data block is
shown in Section 5.2.9 and the basics of the interpolation principle are illustrated in Fig. 5.10.
The line position (PEAK) is split into a coarse position and a fine position (sub-pixel). The coarse
position is based on the pixel pitch and is transferred in PEAK [15:6] (PEAK[15:4] in 3D04). The
sub-pixel position that was calculated from the Peak Detector algorithm (6 bit sub-pixel
information in 3D03, 4 bit sub-pixel in 3D04) is mapped to PEAK [5:0] (PEAK[3:0] in 3D04) (see
also Section 5.2.9).
Fig. 5.11 shows a comparison of the peak detector algorithm of the MV1-D2048-3D03/04
cameras against the Center Of Gravity (COG) algorithm that is used in most triangulation
systems. It can clearly be observed that the Peak Detector algorithm gives more accurate
results.
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