acknowledgements for ansi/nist-itl 1-2011 - NIST Visual Image ...

ANSI/NIST-ITL 1-2011 - UPDATE 2013 DRAFT VERSIONThe fourth information item, radius of position uncertainty/ RPU, is optional. It is 0(default) if the location is known precisely; if the precise location cannot be determined (such asdue to poor clarity), the position is marked at the best estimate of position, with a radiusincluding the area of other possible locations, in integer units of 10 micrometers (0.01mm). Theradius of uncertainty can overlap the edge of the image.Table 119: Explanation of methods of determining center point of reference locationsName Code DescriptionLateral center onlyLThe center location is defined laterally (across the finger) but is notmeaningful in the other dimension (longitudinally, or along the finger), suchas for defining the center line of arches, tips, and lower joints. Lateral centeris only meaningful if the orientation ( Field 9.301: EFS orientation / ORT)is known; the point marked is the center with respect to the orientation angle.Uppermost point of the ridgewith greatest curvatureOverall fingerprint focal point 10For a fingerprint with a known or estimated orientation, the center point isdetermined by finding the highest point of each ridge that is convex andpointing upward, and measuring the curvature/peak angle by following theridge 1.63mm (0.064in) in both directions from that point, as shown inFigure 36. The point with the minimum angle (greatest curvature) is thecenter point of reference.The overall fingerprint focal point is the point where the lines perpendicularto ridge flow converge. as shown in Figure 37. The point of convergence isdetermined in terms of least squares (see, e.g., Novikov and Kot (1998) 200Figure 35: Lateral center example200Novikov S.O and Kot V.S.; “Singular Feature Detection and Classification of Fingerprints using HoughTransform”; Proc. Of SPIE (Int. Workshop on Digital Image Processing and Computer Graphics (6 th ):Applications in Humanities and Natural Sciences); vol 3346, pp 259-269, 1998May, 2013 DRAFT VERSION UPDATE 2013 Page 495