Clearance Checker

This page describes the Orbit desktop extension “Clearance Checker”.

Main Toolbar > Extensions > Clearance Checker

Concepts

The Clearance checker extension calculates the lowest clearance of overhanging objects or constructions above a surface.

Source

Use the generic workflow for Point Cloud Based Extensions to define the source file.

The method for the range of interest is 'Path', 'Multiple Paths', 'Area' and 'Multiple Areas'.

Group By

Clusters of points

For every area or path, the point cloud gets divided into clusters. For each cluster, the lowest clearance will be calculated.

Areas of interest

For every area or path, the lowest clearance will be calculated.

Ground Reference

Choose one of the below-described options to define the Ground Reference:

Point Cloud lowest Z

The lowest z-value of the point cloud.

Point Cloud Z below trajectory

The lowest z-value of the first point cloud cluster found below the trajectory.

Trajectory offset

Enter a fixed vertical offset from the trajectory - Ref. Advanced Parameters (see below).

Fixed height

Enter a fixed z-value - Ref. Advanced Parameters (see below).

Use paths

The source path(s) are used to set the ground reference.

Parameters

Define parameters for the detection:

Pixel Size

The pixel size defines the grid size of the DEMs that are created. For every pixel, the lowest clearance is calculated.

Margin ground

The vertical offset between the Ground Reference that will be excluded from the analysis.

Advanced Parameters

The advanced set of parameters can be accessed by small grey circle above basic parameters.

Algorithm:

  • Pixel Pts Min: The minimum number of points from the point cloud within the column above a pixel, pixels that include less points are not used to define floor and ceiling.
  • Slice Thickness: The thickness of horizontal slices to define ground and ceiling within each pixel.
  • Slice Pts Min: The minimum number of points in a horizontal slice to define floor and ceiling of a pixel.
  • Clearance Pixels Min: The minimum number of pixels a cluster should have. The final floor and ceiling are defined by a cluster of pixels.
  • Fixed Ground Height: Value used as the Ground Reference (default = -999).
  • Trajectory Offset: Vertical offset from the trajectory height.

Output:

  • Missing Sample: The value that will be used for the clearance.omi raster created if there are no overhanging objects (default = -999).

Results

The Hit count is the number of clearances found.

  • Z range: Value of the clearance.
  • #pnts: Number of points defining the ceiling of the clearance.
  • OK: Flag on for checked points.

DEM files are added to the Dataset List by default and are saved in the corresponding folder (see above).

  • Clearance
  • Cluster_min_clearance
  • Ground
  • Pixel_z_range

Clearance Checker Tab

In the Clearance Checker Tab all Clearance Projects are shown including the results and metadata. Standard operations like detaching and maximizing tab are available. Merging projects can be done by clicking the yellow merge icon.

 
Last modified:: 2022/07/29 07:53