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