An Overview of Activities at NIST Toward the Proposed ASTM E57 3D Imaging System Point-to-Point Standard

Abstract

Terrestrial laser scanners (TLSs) are a class of 3D imaging systems that measure the 3D coordinates of an object in their work volume. These coordinates are captured using a ranging unit mounted on two rotation stages that are orthogonal to each other, as seen in figure 1. They are used for a variety of applications, such as large-scale assembly, surveying, forensics, and reverse engineering, among others. The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST), along with various other organizations, has been involved in the development of a documentary standard for 3D imaging instruments that acquire data in a spherical coordinate system. NIST led this effort and possesses unique expertise for this task. This expertise comes from NIST’s prior experience on standardization activities related to laser trackers that also use spherical coordinate system and have very similar error sources. TLSs were being used at NIST in several research projects starting in the early 2000s. It soon became clear that there was a need to evaluate the instruments and determine the uncertainty of the measurements obtained. In this context, NIST organized four workshops between 2003 and 2006 which convened instrument manufacturers, end users, and organizations like NIST to determine the needs of all the stakeholders. 1,2 During these workshops, the participants agreed upon the need for standard terminology, artifacts, and standardized protocols to evaluate