Assessing the alignment between geometry and colors in TLS colored point
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Date
2023
Publication Type
Conference Paper
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yes
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Abstract
The integration of the color information from RGB cameras with the point cloud geometry is used in numerous applications. However, little attention has been paid on errors that occur when aligning colors to points in terrestrial laser scanning (TLS) point clouds. Such errors may impact the performance of algorithms that utilize colored point clouds. Herein, we propose a procedure for assessing the alignment between the TLS point cloud geometry and colors. The procedure is based upon identifying artificial targets observed in both LiDAR-based point cloud intensity data and camera-based RGB data, and quantifying the quality of the alignment using differences between the target center coordinates estimated separately from these two data sources. Experimental results with eight scanners show that the quality of the alignment depends on the scanner, the software used for colorizing the point clouds, and may change with changing environmental conditions. While we found the effects of misalignment to be negligible for some scanners, they exhibited clearly systematic patterns exceeding the beam divergence, image and scan resolution for four of the scanners. The maximum deviations were about 2 mrad perpendicular to the line-of-sight when colorizing the point clouds with the respective manufacturer’s software or scanner in-built functions, while they were up to about 5 mrad when using a different software. Testing the alignment quality, e.g., using the approach presented herein, is thus important for applications requiring accurate alignment of the RGB colors with the point cloud geometry.
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Publication status
published
Book title
Volume
X-1/W1-2023
Pages / Article No.
597 - 604
Publisher
Copernicus
Event
ISPRS Geospatial Week 2023
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
Terrestrial laser scanning (TLS); scanner calibration; point cloud colorization; built-in RGB camera
Organisational unit
03964 - Wieser, Andreas / Wieser, Andreas