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TerraMatch User Guide

Navigation: TerraMatch User Guide > Tool Reference > Match tool box

Find Intensity Correction

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Find Intensity Correction

m_find_intensity_correctionFind Intensity Correction tool solves intensity corrections based on the range of a point from the scanner. This is useful for mobile laser data if the intensity values of points systematically increase with the point’s 3D distance from the scanner.

Finding intensity corrections requires laser data from overlapping strips or scanners and preferable from a hard surface, such as a road surface. The points on the surface must be classified into a separate class. The correction is computed per scanner by comparing intensity values of one scanner with all other points within a given sample radius.

The tool provides correction values for range intervals in a TerraMatch correction file. This correction file can then be used to apply the corrections to the laser data of a project. There is also an option of smoothing the correction values.

Intensity correction should be done when strips have been matched but the overlap between strips is not yet cut off. It may help to improve the result of extracting vector elements for paint markings automatically or for generating intensity ortho images with TerraScan.

To find intensity correction:

1. Load laser data into TerraScan from an area that is suitable for finding intensity corrections.

2. Select the Find Intensity Correction tool.

This opens the Find Intensity Correction dialog:

find_intensity_correction

3. Define settings and click OK.

Setting

Effect

Minimum range

Minimum 3D distance from the scanner used for computing the intensity correction values.

Maximum range

Maximum 3D distance from the scanner used for computing the intensity correction values.

Range interval

Distance interval for computing correction values. One correction value is computed for each interval within Minimum range and Maximum range.

Sampling radius

Distance around each point for comparing the point’s intensity value of one scanner with the average intensity values of all other points.

Trajectory dir

Directory containing TerraScan trajectory files.

Use classes

Classes to use for finding intensity corrections.

This opens the Intensity Correction Results dialog:

intensity_correction_results

4. Define settings.

Setting

Effect

Scanner

Number of the scanner for which to apply intensity correction values.

Smoothing

Number of smoothing rounds to apply to the correction curve.

Fill ends

How to assign correcion values to points for which there is no observation within the given Minimum and Maximum range:

Approach zero - correction values linearly approach zero.

Closest observation - uses correction value of the closest range interval with an observation.

File / Save correction

Saves a TerraMatch correction file for being used in the Apply Correction tool.

5. Save the corrections using the Save corrections command from the File pulldown menu.

6. Close the Intensity Correction Results dialog.

7. Apply the range corrections to laser data using the Apply Correction tool.

TerraMatch User Guide   05.07.2021   © 2021 Terrasolid Ltd