Subject: Re: [boost] Fwd: [gsoc17] Regarding Boost.Geometry
From: Adam Wulkiewicz (adam.wulkiewicz_at_[hidden])
Date: 2017-03-21 14:03:42
Aditya Gupta Via Boost wrote:
> Hi I am Aditya Gupta, IInd Yr. B. Tech. Computer Science at IIT Ropar and I
> wish to work on Project 3 of Boost.Geometry (Nearly antipodal points
> distance accuracy improvement.)
> I have completed the competency test
> <https://github.com/adityagupta1089/earth-geometry>, but I think maybe it
> was too small or have I misinterpreted, anyways.
So you used a sphere as a model of the Earth, haversine formula to
calculate distance and compared it with Boost.Geometry
spherical_equatorial coordinate system.
Try comparing it with Boost.Geometry geographic coordinate system. Is
the result the same?
Why nearly antipodal points may be problematic?
Furthermore there are 3 various ways of calculating geographic distance
in Boost.Geometry but they are not documented yet. In Boost.Geometry
it's possible to specify how the algorithm calculates
cordinate-system-specific parts by passing a strategy into a function as
the last argument. By default, if you don't pass a strategy the
algorithm use the default one (corresponding to the coordinate system of
the pased Geometries). So if you passed geographic points one of the
geographic strategies would be used.
See also this line of a unit test as an example, here the distance is
calculated with one of the strategies passed explicitly into distance()
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