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the laser point and the vertex of the triangle where it is located and the distance from the laser point
to the plane where the triangle is located.
If the angle and the distance are smaller than the values set for the Iteration Angle and Iteration
Distance parameters, the point is identified as a ground point and the triangle mesh is updated. This
process is repeated until all ground points in the mapping area are identified.
Figure: Ground point classification
Ø Building Max Diagonal: Set this parameter based on the largest building in the mapping
area. If this parameter is set to a small value, rooftops may be recognized as ground.
Ø Type of Terrain: DJI Terra provides preset parameters for different types of terrain such
as Flat Ground, Gentle Slope, and Steep Slope. The default parameters suit most common
scenarios. If a mapping area has large undulations, you can increase the iteration angle
and distance as needed.
Ø Generate DEM: If this feature is enabled, DEM data in TIFF format will be generated
based on the point cloud data of ground points. The following scales are supported for
DEM results: 1:500, 1:1000, and 1:2000. You can also set a DEM result resolution based
on the GSD.
Ø Contour: When the contour option is enabled and reconstruction completes, user can
obtain contour output from project path /lidats/terra_contour and import the output file to
a third party software to view and edit.
3.1.3.4. Advanced Settings
Ø Accuracy Control and Check:
Tap the import icon to import checkpoints or control points. Note that the coordinate system should
be the geodetic coordinate system or projected coordinate system, whichever is consistent with the
point cloud coordinate system. After the import, select a checkpoint or control point and tap Start
Processing. Control points can be used to optimize the elevation accuracy of point cloud results and
checkpoints can be used to check the accuracy of point cloud results.
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