A method to evaluate orientation-dependent errors in the center of contrast targets used with terrestrial laser scanners

Published

January 16, 2025

Author(s)

Balasubramanian Muralikrishnan, Xinsu Lu, Mary Gregg, Katharine Shilling, Braden Czapla

Abstract

Terrestrial laser scanners (TLS) are portable dimensional measurement instruments used to obtain 3D point clouds of objects in a scene. While TLSs do not require the use of cooperative targets, they are sometimes placed in a scene to fuse or compare data from different instruments or data from the same instrument but from different positions. A contrast target is an example of such a target; it consists of alternating black/white squares that can be printed using a laser printer. Because contrast targets are planar as opposed to three-dimensional (like a sphere), the center of the target might suffer from errors that depend on the orientation of the target with respect to the TLS. In this paper, we discuss a low-cost method to characterize such errors and present results obtained from a short-range TLS and a long-range TLS. Our method involves comparing the center of a contrast target against the center of spheres, and therefore does not require the use of a reference instrument or calibrated artifacts. For the short-range TLS, systematic errors of up to 0.5 mm were observed in the target center as a function of angle for the two distances (5 m and 10 m) and resolutions (30 points-per-degree (ppd) and 60 ppd) considered for this TLS. For the long-range TLS, systematic errors of about 0.3 mm to 0.8 mm were observed in the target center as a function of angle for the two distances (5 m and 10 m) at low-resolution (28 ppd). Errors of under 0.3 mm were observed in the target center as a function of angle for the two distances at high resolution (109 ppd).

Citation

Sensors

Volume

25

Pub Type

Journals

Download Paper

https://doi.org/10.3390/s25020505

Local Download

Keywords

center error, checkerboard, contrast target, forensics, sphere target, terrestrial laser scanner

Citation

Muralikrishnan, B. , Lu, X. , Gregg, M. , Shilling, K. and Czapla, B. (2025), A method to evaluate orientation-dependent errors in the center of contrast targets used with terrestrial laser scanners, Sensors, [online], https://doi.org/10.3390/s25020505, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959040 (Accessed March 15, 2025)