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Search Publications by: Bala Muralikrishnan (Fed)

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Displaying 26 - 50 of 88

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

Concept to Commercialization of an Artifact for Evaluating 3D Imaging Systems per the ASTM E3125- 17

June 29, 2018
Author(s)
Balasubramanian Muralikrishnan, Prem K. Rachakonda, Vincent D. Lee, Katharine M. Shilling, Daniel S. Sawyer, Geraldine S. Cheok, Luc Cournoyer, Joe Gleason
The newly released ASTM E3125-17 standard describes several point-to-point distance tests to evaluate the performance of spherical coordinate 3D imaging systems, commonly referred to as terrestrial laser scanners (TLS). The relative-range error test, which

Terrestrial laser scanner geometric error model parameter correlations in the Two-face, Length-consistency, and Network methods of self-calibration

April 26, 2018
Author(s)
Balasubramanian Muralikrishnan, Ling Wang, Prem K. Rachakonda, Daniel S. Sawyer
Terrestrial laser scanners (TLS) are increasingly used in a variety of applications where accuracies on the order of few tenths of a millimeter or smaller are routinely demanded. Self-calibration is a quick and cost-effective way to improve the accuracy of

Method to Determine the Center of a Contrast Target from Terrestrial Laser Scanner Data

November 3, 2017
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan, Daniel S. Sawyer, Ling Wang
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

Challenges in measuring spherical geometry using terrestrial laser scanners

November 1, 2017
Author(s)
Balasubramanian Muralikrishnan, Prem K. Rachakonda, Katharine M. Shilling, Vincent D. Lee, Daniel S. Sawyer, Geraldine S. Cheok, Luc Cournoyer
Terrestrial laser scanners (TLS) measure 3D coordinates in a scene by recording the range, the azimuth angle, and elevation angle of discrete points on target surfaces. They are increasingly used in a variety of applications, including manufacturing and

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

October 16, 2017
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan, Katharine M. Shilling, Geraldine S. Cheok, Daniel S. Sawyer
The Dimensional Metrology Group (DMG) at the National Institute of Standards & 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

Methods and Considerations to Determine Sphere Center from Terrestrial Laser Scanner Point Cloud Data

September 6, 2017
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan, Luc Cournoyer, Geraldine S. Cheok, Vincent D. Lee, Katharine M. Shilling, Daniel S. Sawyer
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) is performing research to support the development of documentary standards within ASTM E57 committee. This committee is addressing the point-to-point

Techniques to Evaluate Terrestrial Laser Scanner Errors

July 26, 2017
Author(s)
Bala Muralikrishnan, Prem K. Rachakonda
Forensic photography has been one of the most important tool for investigators over many decades. They preserve the history of the scene and provides a way for investigators to revisit the scene. However, it is difficult to ascertain any objective

Relative range error evaluation of terrestrial laser scanners using a plate, a sphere, and a novel dual-sphere-plate target

July 21, 2017
Author(s)
Balasubramanian Muralikrishnan, Prem K. Rachakonda, Vincent D. Lee, Katharine M. Shilling, Daniel S. Sawyer, Geraldine S. Cheok
Terrestrial laser scanners (TLS) are a class of 3D imaging systems that produce a 3D point cloud by measuring the range and two angles at different sampling locations. The ranging unit of a TLS realizes the SI unit of length. Relative range error is one

Targets for Relative Range Error Measurement of 3D Imaging Systems

May 1, 2017
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan, Katharine M. Shilling, Geraldine S. Cheok, Vincent D. Lee, Christopher J. Blackburn, Dennis S. Everett, Daniel S. Sawyer
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) is performing research to support the development of documentary standards within ASTM E57 for the point-to-point performance evaluation of 3D imaging

Report on the May 2016 ASTM E57.02 instrument runoff at NIST, Part 1 Background information and key findings

October 19, 2016
Author(s)
Balasubramanian Muralikrishnan, Prem K. Rachakonda, Katharine M. Shilling, Vincent D. Lee, Christopher J. Blackburn, Daniel S. Sawyer, Geraldine S. Cheok, Luc Cournoyer
There is ongoing activity within ASTM E57.02 working group WK43218 [1] to develop a documentary standard for point-to-point distance performance evaluation of 3D imaging systems. The Dimensional Metrology Group (DMG) at the National Institute of Standards

Report on the May 2016 ASTM E57.02 instrument runoff at NIST, Part 2 - NIST realization of test procedures and uncertainties in the reference lengths

October 19, 2016
Author(s)
Balasubramanian Muralikrishnan, Prem K. Rachakonda, Katharine M. Shilling, Vincent D. Lee, Christopher J. Blackburn, Daniel S. Sawyer, Geraldine S. Cheok, Luc Cournoyer
There is ongoing activity within ASTM E57.02 working group WK43218 [1] to develop a documentary standard for point-to-point distance performance evaluation of 3D imaging systems. The Dimensional Metrology Group (DMG) at the National Institute of Standards

Targets for Relative Range Error Measurement of 3D Imaging Systems.

July 25, 2016
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan, Katharine M. Shilling, Geraldine S. Cheok, Vincent D. Lee, Christopher J. Blackburn, Dennis S. Everett, Daniel S. Sawyer
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) is performing research to support the development of documentary standards within ASTM E57 for the point-to-point performance evaluation of 3D imaging

Laser Trackers for Large Scale Dimensional Metrology: A Review

March 25, 2016
Author(s)
Balasubramanian Muralikrishnan, Steven D. Phillips, Daniel S. Sawyer
Thirty years since their invention, laser trackers are now recognized as the measurement tool of choice in the manufacture and assembly of large components. While their general design, i.e., a ranging unit on a two-axis gimbal, has not changed

Performance evaluation of a laser tracker hand held touch probe

November 4, 2015
Author(s)
Bala Muralikrishnan, Christopher J. Blackburn, Prem K. Rachakonda, Daniel S. Sawyer
Hand-held touch probes and laser scanners are increasing the scope and applicability of laser trackers. While methods to evaluate the performance of laser trackers in conjunction with spherically-mounted retro-reflectors (SMRs) are well established

Evaluation of the Range Performance of Laser Scanners Using Non-planar Targets.

November 1, 2015
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan, Craig M. Shakarji, Vincent D. Lee, Daniel S. Sawyer
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) is supporting the development of documentary standards for performance evaluation of Laser scanners. This evaluation could be performed by determining the

Towards the Development of a Documentary Standard for Derived-Point to Derived-Point Distance Performance Evaluation of Spherical Coordinate 3D Imaging Systems

October 30, 2015
Author(s)
Balasubramanian Muralikrishnan, Katharine M. Shilling, Prem K. Rachakonda, Wei Ren, Vincent D. Lee, Daniel S. Sawyer
This paper describes ongoing research work within the Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) in support of the development of a documentary standard for derived-point to derived-point distance

Techniques to Evaluate Laser Scanners for Advanced Manufacturing Applications

July 23, 2015
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan, Katharine M. Shilling, Daniel S. Sawyer, Geraldine S. Cheok, Kamel S. Saidi
Laser scanners have become indispensable tools for fast and accurate 3D image acquisition applications such as part inspection, reverse engineering, cultural heritage digitization, surveying, automotive robotic navigation etc. The Dimensional Metrology

Volumetric Performance Evaluation of a Laser Scanner Based on Geometric Error Model

January 5, 2015
Author(s)
Balasubramanian Muralikrishnan, Massimiliano M. Ferrucci, Daniel S. Sawyer, Grant Gerner, Vincent D. Lee, Christopher J. Blackburn, Steven D. Phillips, Yuri Yakovlev, Andrey Astrelin, Spike Milligan, John Palmateer
We discuss a geometric error model for those large volume laser scanners that have the laser source and a spinning prism mirror mounted on a platform that can rotate about the vertical axis. We describe the terms that constitute the model, address their

In-situ Temperature Calibration Capability for Dimensional Metrology

December 15, 2014
Author(s)
Prem K. Rachakonda, Daniel S. Sawyer, Balasubramanian Muralikrishnan, Christopher J. Blackburn, Craig M. Shakarji, Gregory F. Strouse, Steven D. Phillips
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) has developed a new in-situ temperature calibration system. This paper discusses the system components, an in-situ calibration procedure, the uncertainty

In-situ Temperature Calibration Capability for Dimensional Metrology

December 1, 2014
Author(s)
Prem K. Rachakonda, Daniel S. Sawyer, Balasubramanian Muralikrishnan, Christopher J. Blackburn, Craig M. Shakarji, Gregory F. Strouse, Steven D. Phillips
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) has the capability to perform large range dimensional measurements in a facility, called the Tape Tunnel. The Tape Tunnel is equipped with a 60 m long steel
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