3D Imaging Systems Standards Work Is Under Way

As 3D imaging systems continue to find acceptance across numerous industries and in various applications, it becomes more vital that stakeholders have the tools they need to compare the performance of the products that are available. ASTM International has brought together technical experts in the 3D imaging field to develop standards that will provide a fair basis for comparison and foster competition and push manufacturers to develop better-performing systems. The committee is called ASTM Committee E57 on 3D Imaging Systems. The name reflects the fact that the committee addresses issues for laser scanners, LADAR (laser detection and ranging), optical range cameras, and other 3D imaging technologies.

The committee was formed in 2006, but its beginnings go back almost a decade. In 1999, the National Institute of Standards and Technology (NIST) initiated research on the use of 3D imaging systems in construction. That research indicated that there was a need for standard performance specifications for 3D imaging systems and the data that they provide. Between 2004 and 2006, NIST held four workshops on the performance of 3D imaging systems. The user community decided to formalize the standards process. They selected ASTM as the standards development organization to house the 3D imaging standards work. Initially, the impetus for E57 started from a group that was interested in longer-range instruments, for construction, large-scale historical preservation, mining, transportation, industrial-plant surveying, offshore-oil-platform surveying, and similar applications. During the meeting held in January 2008, a Task Group was formed to initiate standards efforts for short-range instruments (i.e., < 2 m) that would be used in manufacturing, for reverse engineering, process verification, inspection, and facial recognition among other applications. Leading E57 is chair Alan Lytle of the NIST Construction Metrology and Automation Group. Within E57 there are four subcommittees—Terminology, Test Methods, Best Practices, and Data Interoperability led by Subcommittee Chairs Gerry Cheok of NIST, Dave Ober of Metris, Ted Knack of Riegl, and Gene Roe of AutoDesk, respectively.

The Terminology Subcommittee has an active standard in place, ASTM E2544-07a Standard Terminology for Three-Dimensional (3-D) Imaging Systems. The subcommittee continues to work to gather into a single document common terms, their definitions and descriptions, nomenclature, and acronyms associated with 3D imaging systems. Lytle anticipates that they will resolve a second round of balloting for additional terms in late January. “I expect to have a second edition in place in February,” he says.

The Test Methods Subcommittee has in place a ranging protocol working document, WK12373 New Standard Practice for Evaluating the Range Performance of Three-Dimensional (3D) Imaging Systems. The protocol provides requirements and methods for specifying and testing the range measurement performance of 3D imaging systems. “There are complications with this,” Lytle says. “There are a lot of what seem to be minor details that play important parts in being able to understand how the systems perform, so we’re trying to get an established protocol that at least a majority of the manufacturers agree to.” 3D imaging systems measure rapid pulses, as many as thousands of measurements per second, to detect the range and bearing of points on an object or off of a surface within a larger area, arranging spatial and other information such as color and intensity data into an image called a “point cloud.” To evaluate the performance of such a system requires the specification of criteria. “That’s what you wrestle with,” Lytle says. “What’s a material that is a reasonable target material across the range of frequencies that these instruments are currently employing? What are the shapes? Do you use a flat, planar target? Do you use a spherical type of target? There are other recommendations for other types of targets as well. This ranging protocol is the first working document to get that in place. It will be the first work product coming out of the Test Methods Subcommittee.” Lytle believes that the committee will have a balloted, approved ranging protocol standard by summer.

The Best Practices Subcommittee is currently working on a best practice for safety that Lytle hopes will be balloted by summer; and the Data Interoperability Subcommittee has internally released a working document, a requirements specification, for an exchange protocol for 3D image data.

As the work proceeds, Lytle encourages others to get involved. Anyone who is interested in participating in the process can contact him at alan.lytle@nist.gov or find information through the ASTM website at astm.org.

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