NIST-developed algorithms reveal fundamental flaws in coordinate measuring machine fitting software. (General Developments).NIST (National Institute of Standards & Technology, Washington, DC, www.nist.gov) The standards-defining agency of the U.S. government, formerly the National Bureau of Standards. It is one of three agencies that fall under the Technology Administration (www.technology. researchers recently presented new findings which indicate that serious problems can exist in some fitting algorithms used by commercial software packages. Coordinate measuring systems rely on embedded software Instructions that permanently reside in a ROM or flash memory chip. Embedded software may be immediately available to the CPU or, for faster execution, may be transferred to RAM first and then executed. algorithms to fit geometric shapes This is a list of geometric shapes. Generally composed of straight line segments
ASPE American Society of Plumbing Engineers ASPE American Society for Precision Engineering ASPE Association of Standardized Patient Educators ), a NIST researcher presented alarming results demonstrating the problems discovered during a comparison between NIST reference results and results from commercial metrology metrology Science of measurement. Measuring a quantity means establishing its ratio to another fixed quantity of the same kind, known as the unit of that kind of quantity. software packages. For some geometric shapes and non-least-squares fit objectives, the algorithms used in the commercial software deviated from the NIST results significantly. The data sets used were representative of what might reasonably be encountered with many coordinate-measuring systems. Since the whole measurement is only as good as the embedded software used, uncertainty with this software is cause for concem. NIST is making available reference pairs (data sets with their reference fits) that can be used by industry for comparisons with software packages. Reference pairs exist for one- and two-sided fit objectives for lines, planes, circles, spheres, cylinders, and cones Cones Receptor cells that allow the perception of colors. Mentioned in: Color Blindness . Documentation and additional reference data for fitting more general shapes (paraboloids, complex surfaces, etc.) are also available. NIST'S special test service (NIST ATEP-CMS) provides tests for metrology software packages that use least-squares fitting techniques. CONTACT: Craig Shakarji, (301) 975-3545; craig. shakarji@nist.gov |
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