Evaluating the Quality of TLS Point Cloud Colorization

Arttu Julin,Antero Kukko,Juho-Pekka Virtanen,Matti T Vaaja,Hannu Hyyppä,Harri Kaartinen,Toni Rantanen,Matti Kurkela,Mikko Maksimainen,Juha Hyyppä

doi:10.3390/rs12172748

Arttu Julin, Antero Kukko + Show 8 more

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https://doi.org/10.3390/rs12172748

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Abstract

Terrestrial laser scanning (TLS) enables the efficient production of high-density colored 3D point clouds of real-world environments. An increasing number of applications from visual and automated interpretation to photorealistic 3D visualizations and experiences rely on accurate and reliable color information. However, insufficient attention has been put into evaluating the colorization quality of the 3D point clouds produced applying TLS. We have developed a method for the evaluation of the point cloud colorization quality of TLS systems with integrated imaging sensors. Our method assesses the capability of several tested systems to reproduce colors and details of a scene by measuring objective image quality metrics from 2D images that were rendered from 3D scanned test charts. The results suggest that the detected problems related to color reproduction (i.e., measured differences in color, white balance, and exposure) could be mitigated in data processing while the issues related to detail reproduction (i.e., measured sharpness and noise) are less in the control of a scanner user. Despite being commendable 3D measuring instruments, improving the colorization tools and workflows, and automated image processing pipelines would potentially increase not only the quality and production efficiency but also the applicability of colored 3D point clouds.

Highlights

Terrestrial laser scanning (TLS) enables the efficient and detailed collection of 3D point clouds from the real world for a rapidly increasing number of use cases
Despite the widespread application and indisputable usefulness of colored point clouds, insufficient attention has been put into investigating the colorization quality of TLS-derived 3D point clouds
We successfully developed a test method to evaluate the point cloud colorization quality of modern commercial TLS systems with integrated imaging sensors

Summary

Introduction

Terrestrial laser scanning (TLS) enables the efficient and detailed collection of 3D point clouds from the real world for a rapidly increasing number of use cases. Laser scanners usually record the point intensity values and can utilize cameras to derive color values for the 3D point clouds. Color information (most commonly red, green, and blue values of the RGB color model) can be considered as one of the most common, useful, and important types of non-geometric information and typically comprises the radiance captured by an imaging sensor as an integrated part of the 3D measuring system or as a separate external camera. This radiance is affected e.g., by illumination, geometry, and diffuse and specular reflectivity of the target (e.g., [1,2])

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