Thread: distaz

Started: 2011-11-16 20:20:34
Last activity: 2011-11-16 20:20:34
Topics: Web Services
paul denton
distaz
2011-11-16 20:20:34
Does anyone know what earth model the distaz webservice uses to calculate distances (all I can tell is that it appears not to be a spherical earth model)

Thanks

Paul Denton
UK school seismology project leader
British Geological Survey
Keyworth
Nottingham NG12 5GG
email pdenton<at>bgs.ac.uk
web www.bgs.ac.uk/ssp



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  • Chad Trabant
    Re: distaz
    2011-11-16 17:46:36

    Hi Paul,

    This calculation includes an ellipticity correction and the latitudes are assumed to be geographic.

    We are considering the idea of adding the calculated distance assuming geocentric coordinates to the service. This would allow users to supply coordinates in either convention.

    regards,
    Chad

    On Nov 16, 2011, at 4:20 AM, Denton, Paul wrote:

    Does anyone know what earth model the distaz webservice uses to calculate distances (all I can tell is that it appears not to be a spherical earth model)

    Thanks

    Paul Denton
    UK school seismology project leader
    British Geological Survey
    Keyworth
    Nottingham NG12 5GG
    email pdenton<at>bgs.ac.uk
    web www.bgs.ac.uk/ssp




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    is subject to the Freedom of Information Act 2000 and the contents
    of this email and any reply you make may be disclosed by NERC unless
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    NERC may be stored in an electronic records management system. _______________________________________________
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  • Philip Crotwell
    Re: distaz
    2011-11-16 18:26:03
    Hi

    I am not sure, but I suspect what you are seeing is the effect of an
    ellipticity correction.

    If you want code to calculate distance, I have routines in java, c,
    fortran and python here that might be of use. Distance is such a small
    calculation that it might be better done locally.

    http://www.seis.sc.edu/software/distaz/

    Philip

    On Wed, Nov 16, 2011 at 7:20 AM, Denton, Paul <pdenton<at>bgs.ac.uk> wrote:
    Does anyone know what earth model the distaz webservice uses to calculate
    distances (all I can tell is that it appears not to be a spherical earth
    model)

    Thanks

    Paul Denton
    UK school seismology project leader
    British Geological Survey
    Keyworth
    Nottingham NG12 5GG
    email pdenton<at>bgs.ac.uk
    web  www.bgs.ac.uk/ssp



    --
    This message (and any attachments) is for the recipient only. NERC
    is subject to the Freedom of Information Act 2000 and the contents
    of this email and any reply you make may be disclosed by NERC unless
    it is exempt from release under the Act. Any material supplied to
    NERC may be stored in an electronic records management system.
    _______________________________________________
    webservices mailing list
    webservices<at>iris.washington.edu
    http://www.iris.washington.edu/mailman/listinfo/webservices




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