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From "Charles Karney (JIRA)" <>
Subject [jira] [Commented] (SIS-385) Inaccurate formulas in DistanceUtils
Date Wed, 17 Jan 2018 15:02:00 GMT


Charles Karney commented on SIS-385:

The issue descriptions don't quite match the two complaints I made on the mailing list. This
one was referring to problems with the computations on a *sphere* (not an *ellipsoid*). Currently
the SIS routines are sub-standard returning results involving arcsine or arccosine which are
subject to large rounding errors in some cases. I recommend following the methodology in the
Wikipedia article, [Great-circle navigation|],
using the more accurate formulas (involving atan2) where appropriate.

> Inaccurate formulas in DistanceUtils
> ------------------------------------
>                 Key: SIS-385
>                 URL:
>             Project: Spatial Information Systems
>          Issue Type: Bug
>          Components: Referencing
>    Affects Versions: 0.1-incubating, 0.2-incubating, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8
>            Reporter: Martin Desruisseaux
>            Priority: Major
>             Fix For: 1.0
> The {{DistanceUtils}} class has the following problems:
> * Inaccurate formula in {{getPointOnGreatCircle}}.
> * Inaccurate formula in {{getHaversineDistance}}.
> * Misnamed {{getHaversineDistance}} method.
> Charles Karney kindly provided descriptions of the problems [on the developer mailing
together with proposed fixes. One possible action is to deprecate {{DistanceUtils}} in favor
of something like the {{GeodeticCalculator}} class [in the Geotk project|].
That class is a port in Java of following Fortran code:
> * subroutine DIRECT1.
> * subroutines GPNARC
(version 200005.26) and GPNHRI (version 200208.09) written by Robert (Sid) Safford.
> But we may take another source if suitable, for example [|].

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