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Search Publications by: Daniel S. Sawyer (Fed)

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Displaying 1 - 25 of 143

Laser tracker and terrestrial laser scanner range error evaluation by stitching

May 7, 2024
Author(s)
Balasubramanian Muralikrishnan, Braden Czapla, Vincent Lee, Craig Shakarji, Daniel S. Sawyer, Saure Matthias
Laser trackers (LTs) are dimensional measurement instruments commonly employed in the manufacture and assembly of large structures. Terrestrial laser scanners (TLSs) are a related class of dimensional measurement instruments more commonly employed in

Laser tracker interim testing per the ASME B89.4.19-2021 and ISO 10360-10:2021 standards

June 28, 2023
Author(s)
Marcos Motta de Souza, Bala Muralikrishnan, Vincent Lee, Daniel S. Sawyer
The recently revised ASME B89.4.19-2021 and ISO 10360-10:2021 standards for laser trackers include a new interim test that is comprehensive and more sensitive to systematic errors than the interim tests in the previous versions of the standards, i.e., the

Performance evaluation of laser trackers using the network method

July 30, 2020
Author(s)
Ling Wang, Balasubramanian Muralikrishnan, Octavio Icasio Hernandez, Craig M. Shakarji, Daniel S. Sawyer
Due to their accuracy, portability, and large working volume, laser trackers (LTs) are widely used for dimensional metrology in a variety of large-scale manufacturing and assembly operations. Their performance evaluation is a key concern for users

Improvised Long Test Lengths via Stitching Scale Bar Method: Performance Evaluation of Terrestrial Laser Scanners per ASTM E3125-17

May 28, 2020
Author(s)
Shendong Shi, Balasubramanian Muralikrishnan, Vincent Lee, Daniel S. Sawyer, Octavio Icasio-Hern?ndez
Periodic performance evaluation is a critical issue for ensuring the reliability of data from terrestrial laser scanners (TLSs). With the recent introduction of the ASTM E3125-17 standard, there now exist standardized test procedures for this purpose

Methods to improve the dimensional measurement accuracy of a motion tracking system

April 1, 2020
Author(s)
Shendong Shi, Balasubramanian Muralikrishnan, Vincent D. Lee, Daniel S. Sawyer
Photogrammetry based motion tracking systems are widely used in entertainment, medicine, sports, and other industries for low accuracy positioning applications. Camera-based systems track cooperative markers on objects to obtain their real-time positions

A First realization of ASTM E3125-17 test procedures for laser scanner performance evaluation

February 1, 2020
Author(s)
Ling Wang, Balasubramanian Muralikrishnan, Vincent D. Lee, Prem K. Rachakonda, Daniel S. Sawyer, Joe Gleason
Spherical coordinate three-dimensional (3D) imaging systems, such as Terrestrial Laser Scanners (TLS), are already used widely in different fields. Their measurement performance evaluation is a topic of active research. In 2017, the first comprehensive

Methods to calibrate a three-sphere scale bar for laser scanner performance evaluation per the ASTM E3125-17

February 1, 2020
Author(s)
Ling Wang, Balasubramanian Muralikrishnan, Vincent D. Lee, Prem K. Rachakonda, Daniel S. Sawyer, Joe Gleason
A scale bar with sphere targets is one way of realizing the symmetric and asymmetric length tests to evaluate terrestrial laser scanner (TLS) performance per the ASTM E3125-17 standard. The length of the scale bar is required to be known with an expanded

Sources of Errors in Structured Light 3D Scanners

April 15, 2019
Author(s)
Prem K. Rachakonda, Bala Muralikrishnan, Daniel S. Sawyer
Structured light (SL) scanners have been commercially available for over a decade and some commercial scanners are evaluated using one of two German guidelines – VDI/VDE 2634 parts 2 and/or 3. Several other research groups and NMIs have developed physical

Roles and Responsibilities of NIST in the Development of Documentary Standards

July 27, 2018
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan, Daniel S. Sawyer
The National Institute of Standards and Technology (NIST) is a non-regulatory federal agency of the Department of Commerce and is the national metrology institute of the US. The background of NIST's role in the development of voluntary consensus standards