HT2 - Create a Digital Terrain Model from a T-Lidar point cloud¶

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Objectives¶

This tutorial shows how to :

1. Open a point cloud
2. Add the DTM creation step
3. Configure the tool parameters
4. Export the model in a raster format

Open a ploint cloud¶

Please refer to tutorial HT1 - Load, visualize, crop and export a T-Lidar point cloud.

Add the DTM creation step¶

The OE_StepExtractSoil03 step is found in the onfensamv2 plugin. This step distinguishes ground points from vegetation points and generates:

• a Digital Terrain Model (DTM)
• a Digital Surface Model (DSM)
• a Digital Height Model (DHM)

To add a step, right click on the previous one and then select the tool. Select the onfensamv2 plugin, and then the Soil / vegetation segmentation → DTM step.

Tool parameters configuration¶

Tool steps and parameters:

• A Zmin grid is created at the specified Grid resolution. The resolution must be in centimeters. The same resolution will be used for the output models.

• Point density is calculated for points located between Zmin and “Zmin + Soil thickness”.

• NULL value is given to the grid’s pixels that have a point density smaller than the Minimum density.
• If the Interpolation box is checked, NULL values ares replaced by the average of natural neighbors.
• If the Smoothing box is checked, each cell is transformed according to the K-Nearest Neighbor (k-NN) method. K (Neighborhood in number of pixels) must be specified.

Here is an exemple of a Digital terrain Model (DTM):

Export the model in a raster format¶

Please refer to tutorial HT1 - Load, visualize, crop and export a T-Lidar point cloud.

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