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Search Publications by: Bala Muralikrishnan (Fed)

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Displaying 26 - 50 of 170

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

X-ray computed tomography instrument performance evaluation: Detecting geometry errors using a calibrated artifact

April 30, 2019
Author(s)
Balasubramanian Muralikrishnan, Katharine M. Shilling, Steven D. Phillips, Wei Ren, Vincent D. Lee, Felix H. Kim, Gabriel Alberts, Valentina Aloisi
X-ray computed tomography (XCT) is uniquely suitable for non-destructive dimensional metrology of delicate or internal features generated from the additive manufacturing process. While XCT has long been used in medical imaging, it has only been used for

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

Methods to Characterize 3D Scanners for Forensic Applications

February 22, 2019
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan
Forensic photography has been one of the most valuable tool for investigators over many decades. They preserve the history of the scene and provide a way for investigators to analyze the scene of interest. However, it is difficult to obtain any objective

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