This tool creates a height map from a point cloud. A height map is a 2D representation of the data where the intensity value corresponds to the height (z).

An ROI box is constructed with its center along a line in 3D. A parallel projection is performed, projecting all points perpendicularly onto the view plane. All points within the ROI participate in the height map, but when projected points coincide, only the closest point is used.

3D coordinate system

• Reference - a 3D reference system

View line (new z axis)

A number of options exist to select the line of view for the tool. Each option will create a line, along which an ROI box is created.

Line tool

• Tool - tool with a 3D line result
• Result - tool result to select
• ROI center at
  • Line start - center ROI at line start
  • Line middle - center ROI at line midpoint
  • Line end - center ROI at line end
• Direction
  • Start to end - look from line start to line end (line start is closer)
  • End to start - look from line end to line start (line end is closer)

Explicit line

• X,Y,Z
  • Starting point - line start
  • Direction - line direction

Axis parallel

• X - parallel to the X axis - view line inparallel with X axis
• Y - parallel to the Y axis - view line inparallel with Y axis
• Z - parallel to the Z axis - view line inparallel with Z axis
• Look "down", towards negative - look towards minus infinity
• Look "up", towards positive - look towards plus infinity

ROI

• X,Y,Z
  • Center - ROI box center
  • Size - ROI box dimensions

Output image

• Destination - where to place the result image
• Size (X,Y) - size of output image

Output (pixel) values

• Near - points closer to the view plane have higher intensity values
• Far - points further from the view plane have higher intensity values

Advanced

Point cloud decimation (x & y)

• Factor - keep only every nth sample in x and y directions

Point cloud filter

• Contrast - element 4 in a 5-element point cloud; set min and max allowable value

Pixel filter

This describes a non-linear filter to extract values from a neighbourhood. It is a simple averaging filter, but with a varying number of pixels involved.

• Dynamic (minimizes filtering) - when checked, the filter size is incremented (from 0) for each pixel until a result has been obtained, or max size has been reached. This will ensure a maximum amount ov valid output pixels, while reducing the artifacts resulting from the filter.
• Separate X and Y filtering to correct non rectangular pixels
• Size (max) - window size in both x and y; max size if dynamic filtering
• Min percent - do not produce a result unless at least this many percent of samples are present within the filter window
• Min count - do not produce a result unless at least this many samples are present within the filter window

Output

The final output options may filter and rotate/flip the output image

• Filter - standard filter options
• Rotation - 0, 90, 180 or 270 rotation
• Flip - flip output image horizontal or vertical flip

Visualisation

Points	All points within the ROI
ROI	The ROI cube

Results

Point count	Number of points within ROI
Pitch.x	Number of reference units per pixel in the resulting image, x
Pitch.y	Number of reference units per pixel in the resulting image, y
Height step	Number of reference units per intensity step (0-255)
Height offset	Reference units along the view line from the view line start to the ROI start