Representation of Uncertainty and Confidence in the Presence Information Data Format Location Object (PIDF-LO)
RFC 7459

 
Document Type RFC - Proposed Standard (February 2015; No errata)
Last updated 2015-02-26
Replaces draft-thomson-geopriv-uncertainty, draft-thomson-geopriv-confidence
Stream IETF
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Stream WG state Submitted to IESG for Publication
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Document shepherd Ray Bellis
Shepherd write-up Show (last changed 2014-09-18)
IESG IESG state RFC 7459 (Proposed Standard)
Telechat date
Responsible AD Alissa Cooper
Send notices to geopriv-chairs@ietf.org, draft-ietf-geopriv-uncertainty@ietf.org
IANA IANA review state Version Changed - Review Needed
IANA action state RFC-Ed-Ack
Internet Engineering Task Force (IETF)                        M. Thomson
Request for Comments: 7459                                       Mozilla
Updates: 3693, 4119, 5491                                J. Winterbottom
Category: Standards Track                                   Unaffiliated
ISSN: 2070-1721                                            February 2015

            Representation of Uncertainty and Confidence in
     the Presence Information Data Format Location Object (PIDF-LO)

Abstract

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

   This document normatively updates the definition of location
   information representations defined in RFCs 4119 and 5491.  It also
   deprecates related terminology defined in RFC 3693.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7459.

Thomson & Winterbottom       Standards Track                    [Page 1]
RFC 7459                Uncertainty & Confidence           February 2015

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Thomson & Winterbottom       Standards Track                    [Page 2]
RFC 7459                Uncertainty & Confidence           February 2015

Table of Contents

   1. Introduction ....................................................4
      1.1. Conventions and Terminology ................................4
   2. A General Definition of Uncertainty .............................5
      2.1. Uncertainty as a Probability Distribution ..................6
      2.2. Deprecation of the Terms "Precision" and "Resolution" ......8
      2.3. Accuracy as a Qualitative Concept ..........................9
   3. Uncertainty in Location .........................................9
      3.1. Targets as Points in Space .................................9
      3.2. Representation of Uncertainty and Confidence in PIDF-LO ...10
      3.3. Uncertainty and Confidence for Civic Addresses ............10
      3.4. DHCP Location Configuration Information and Uncertainty ...11
   4. Representation of Confidence in PIDF-LO ........................12
      4.1. The "confidence" Element ..................................13
      4.2. Generating Locations with Confidence ......................13
      4.3. Consuming and Presenting Confidence .......................13
   5. Manipulation of Uncertainty ....................................14
      5.1. Reduction of a Location Estimate to a Point ...............15
           5.1.1. Centroid Calculation ...............................16
                  5.1.1.1. Arc-Band Centroid .........................16
                  5.1.1.2. Polygon Centroid ..........................16
      5.2. Conversion to Circle or Sphere ............................19
      5.3. Conversion from Three-Dimensional to Two-Dimensional ......20
      5.4. Increasing and Decreasing Uncertainty and Confidence ......20
           5.4.1. Rectangular Distributions ..........................21
           5.4.2. Normal Distributions ...............................21
      5.5. Determining Whether a Location Is within a Given Region ...22
           5.5.1. Determining the Area of Overlap for Two Circles ....24
           5.5.2. Determining the Area of Overlap for Two Polygons ...25
   6. Examples .......................................................25
      6.1. Reduction to a Point or Circle ............................25
      6.2. Increasing and Decreasing Confidence ......................29
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