Terrestrial laser scanners (TLSs) are instruments that can measure 3D coordinates of objects at high speed resulting in high density 3D point cloud data without the necessity of a cooperative target. Contrast targets, also known as checkerboard targets, are some of the most common targets used to establish a scale or register multiple point cloud data sets obtained from TLSs. Contrast targets provide a way to determine the geometric center by using intensity data along with the dimensional data. Large contrast targets are needed when scanning at longer distances; however, unlike other geometric targets such as spheres, fabrication of large contrast targets is not expensive. Even though contrast targets have been used with TLSs, the algorithms to calculate their centers are proprietary and/or work only with proprietary data formats. In this context, this paper describes a novel algorithm that was developed at NIST to calculate the derived point or the center of a contrast target and compares its performance with commercial software, in various scan conditions.
Conference Dates: October 29-November 3, 2017
Conference Location: Charlotte, NC
Conference Title: 32nd ASPE Annual Meeting, Charlotte, NC
Pub Type: Conferences
contrast targets, checkerboard targets, laser scanner targets, target center detection