Representation of Uncertainty and Confidence in PIDF-LO
draft-ietf-geopriv-uncertainty-02

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Document Type Active Internet-Draft (geopriv WG)
Last updated 2014-08-26 (latest revision 2014-08-14)
Replaces draft-thomson-geopriv-confidence, draft-thomson-geopriv-uncertainty
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GEOPRIV                                                       M. Thomson
Internet-Draft                                                   Mozilla
Intended status: Standards Track                         J. Winterbottom
Expires: February 15, 2015                                  Unaffiliated
                                                         August 14, 2014

        Representation of Uncertainty and Confidence in PIDF-LO
                   draft-ietf-geopriv-uncertainty-02

Abstract

   The key concepts of uncertainty and confidence as they pertain to
   location information are defined.  Methods for the manipulation of
   location estimates that include uncertainty information are outlined.

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Thomson & Winterbottom  Expires February 15, 2015               [Page 1]
Internet-Draft          Uncertainty & Confidence             August 2014

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Conventions and Terminology . . . . . . . . . . . . . . .   3
   2.  A General Definition of Uncertainty . . . . . . . . . . . . .   4
     2.1.  Uncertainty as a Probability Distribution . . . . . . . .   5
     2.2.  Deprecation of the Terms Precision and Resolution . . . .   7
     2.3.  Accuracy as a Qualitative Concept . . . . . . . . . . . .   7
   3.  Uncertainty in Location . . . . . . . . . . . . . . . . . . .   8
     3.1.  Targets as Points in Space  . . . . . . . . . . . . . . .   8
     3.2.  Representation of Uncertainty and Confidence in PIDF-LO .   9
     3.3.  Uncertainty and Confidence for Civic Addresses  . . . . .   9
     3.4.  DHCP Location Configuration Information and Uncertainty .  10
   4.  Representation of Confidence in PIDF-LO . . . . . . . . . . .  10
     4.1.  The "confidence" Element  . . . . . . . . . . . . . . . .  11
     4.2.  Generating Locations with Confidence  . . . . . . . . . .  12
     4.3.  Consuming and Presenting Confidence . . . . . . . . . . .  12
   5.  Manipulation of Uncertainty . . . . . . . . . . . . . . . . .  13
     5.1.  Reduction of a Location Estimate to a Point . . . . . . .  13
       5.1.1.  Centroid Calculation  . . . . . . . . . . . . . . . .  14
         5.1.1.1.  Arc-Band Centroid . . . . . . . . . . . . . . . .  14
         5.1.1.2.  Polygon Centroid  . . . . . . . . . . . . . . . .  15
     5.2.  Conversion to Circle or Sphere  . . . . . . . . . . . . .  17
     5.3.  Three-Dimensional to Two-Dimensional Conversion . . . . .  18
     5.4.  Increasing and Decreasing Uncertainty and Confidence  . .  19
       5.4.1.  Rectangular Distributions . . . . . . . . . . . . . .  19
       5.4.2.  Normal Distributions  . . . . . . . . . . . . . . . .  20
     5.5.  Determining Whether a Location is Within a Given Region .  20
       5.5.1.  Determining the Area of Overlap for Two Circles . . .  22
       5.5.2.  Determining the Area of Overlap for Two Polygons  . .  23
   6.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .  23
     6.1.  Reduction to a Point or Circle  . . . . . . . . . . . . .  23
     6.2.  Increasing and Decreasing Confidence  . . . . . . . . . .  27
     6.3.  Matching Location Estimates to Regions of Interest  . . .  27
     6.4.  PIDF-LO With Confidence Example . . . . . . . . . . . . .  28
   7.  Confidence Schema . . . . . . . . . . . . . . . . . . . . . .  28
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  30
     8.1.  URN Sub-Namespace Registration for
           urn:ietf:params:xml:ns:geopriv:conf . . . . . . . . . . .  30
     8.2.  XML Schema Registration . . . . . . . . . . . . . . . . .  30
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