Re: Geo::Ellipsoid module

Jim Gibson wrote: 

DEFINED ELLIPSOIDS
        The following ellipsoids are defined in Geo::Ellipsoid, with the
        semi-major axis in meters and the reciprocal flattening as
        shown. The default ellipsoid is WGS84.

            Ellipsoid        Semi-Major Axis (m.)     1/Flattening
            ---------        -------------------     ---------------
            WGS84                6378137.0           298.25722210088
            NAD27                6378206.4           294.9786982138
            AIRY                 6377563.396         299.3249646
            AIRY-MODIFIED        6377340.189         299.3249646
            AUSTRALIAN           6378160.0           298.25
            BESSEL-1841          6377397.155         299.1528128
            CLARKE-1880          6378249.145         293.465
            EVEREST-1830         6377276.345         290.8017
            EVEREST-MODIFIED     6377304.063         290.8017
            FISHER-1960          6378166.0           298.3
            FISHER-1968          6378150.0           298.3
            HOUGH-1956           6378270.0           297.0
            HAYFORD              6378388.0           297.0
            KRASSOVSKY-1938      6378245.0           298.3
            NWL-9D               6378145.0           298.25
            SOUTHAMERICAN-1969   6378160.0           298.25
            SOVIET-1985          6378136.0           298.257
            WGS72                6378135.0           298.26


How about GRS80? Or IAU76 if you're interested in what the astronomers are doing. Apparently the U.S. Department of commerce has its own variant of GRS80, with the same semimajor, but more decimal places than the "standard" standard. This per http://biology.usgs.gov/fgdc.metadata/version2/spref/horiz/geodet/faq.htm Oddly, I can't figure out where to get the International Astronomical Union's ellipsoid from their web site. Buried under some subcommittee, I guess. I got it from Jean Meeus' "Astronomical Algorithms", but

Letting the user define his/her own reference ellipsoid is a good idea, also. Can it be done at the class level as well as the object leve, so that (e.g.) "sphere" becomes, at least for the life of the Perl script, a defined ellipsoid?

Could you define/document the behavior of set_ellipsoid() if the given ellipsoid is invalid?

But these are really all nit-picks. I would go for it.

Thanks for the opportunity to comment,
Tom Wyant
.

Relevant Pages

  • Re: Geo::Ellipsoid module
    ... ellipsoid, and I have added it as a separate option with the same values as WGS84. ... If you specify an ellipsoid that is not in the list, ... for undefined or zero reciprocal flattening, ...
    (comp.lang.perl.modules)
  • Re: Geo::Ellipsoid module
    ... he did not mean designing a module API at that ... If you specify a custom ellipsoid, ... >> for undefined or zero reciprocal flattening, ...
    (comp.lang.perl.modules)