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Defining the LLE Algorithm

The GenICam feature Scan3dExtractionMethod gives access to all available LLE Algorithms.
Figure 13 – Laser Line Extraction options shows how this feature is presented in GenICam Browser.

Figure 13 – Laser Line Extraction options

The choice between the available algorithms depends on a number of factors related to the target application. We highlight here the main differences among the available algorithms.

ROI YSize

The number of effective vertical pixels in a ROI (YSize) is limited by the maximum integer value that can be represented by the output format of the chosen algorithm as described below:

  • MaxDetection_8 (8-bit): 254. The value 255 is reserved to indicate an InvalidDataFlag.
  • MaxDetection_16 (16-bit): 65534. The value 65535 is reserved to indicate an InvalidDataFlag.
  • PeakDetection_11_5 (UQ11.5): almost 2048. The value (2048 - 1/32) is reserved to indicate an InvalidDataFlag.
  • PeakDetection_8_8 (UQ8.8): almost 256. The value (256 - 1/256) is reserved to indicate an InvalidDataFlag.
  • CenterOfGravity_11_5 (UQ11.5): almost 2048. The value (2048 - 1/32) is reserved to indicate an InvalidDataFlag.
  • CenterOfGravity_8_8 (UQ8.8): almost 256. The value (256 - 1/256) is reserved to indicate an InvalidDataFlag.

Algorithm Resolution

The position resolution of the available algorithms varies from 1 pixel up to 1/256 pixel as described below:

  • MaxDetection_8 (8-bit): 1 pixel.
  • MaxDetection_16 (16-bit): 1 pixel.
  • PeakDetection_11_5 (UQ11.5): 1/32 pixel.
  • PeakDetection_8_8 (UQ8.8): 1/256 pixel.
  • CenterOfGravity_11_5 (UQ11.5): 1/32 pixel.
  • CenterOfGravity_8_8 (UQ8.8): 1/256 pixel.

Algorithm Specificities

As mentioned previously, the choice of an LLE algorithm strongly depends on the target application. Following, a description of the main features of each LLE algorithm from the application point of view:

  • MaxDetection_8 (8-bit): This version of the MaxDetection module with an 8-bit depth map output generates a very small amount of data which requires less computing performance from the 3D post-processing stage.
  • MaxDetection_16 (16-bit): With its 16-bit integer depth map output, the version of the MaxDetection module can support very large input ROIs.
  • PeakDetection: The two versions of the PeakDetection module offer a trade-off between sub-pixel resolution and maximum effective ROI size. The PeakDetection was designed to be insensitive to intensity-dependent biases.
  • CenterOfGravity: The two versions of the CenterOfGravity module also offer a trade-off between sub-pixel resolution and maximum effective ROI size. The CenterOfGravity was designed to be robust to noisy inputs and wide lines.