Aleksandar, Thank-you for the clarification. As John said, with the diagram, everything becomes clear.
But I fear I have no good suggestion on the way to name this parameter. Spontaneously, I would say something like "azimuth_of_sensor_seen_from_observed_point", but, clearly, this doesn't follow the guidelines for construction of CF Standard Names. At least, does this correctly reflect what you mean ? Bruno. Le 15/01/2013 03:20, Aleksandar Jelenak - NOAA Affiliate a écrit : > Bruno, John: > > platform_azimuth_angle defines an angle where the observation point is > at the vertex, one side of the angle points north, the other side > points to the platform, and the angle is calculated clockwise from the > north. The observation point is defined by an instrument on the > platform. > > Here's one diagram explaining this angle: > http://science-edu.larc.nasa.gov/SCOOL/images/azimuth.gif > > platform_azimuth_angle in the diagram is labelled "Satellite Azimuth > from North". The observation target is labelled "Where You Are". > > I don't agree the definition is weak. It mentions that "platform" > means the vehicle from which *observations* are made, and clearly > indicates that *observation target* is at the vertex of this angle. > Perhaps the confusion is arising from the term "azimuth" as it is > widely used in ship and airplane navigation. > > I opted for "platform" in the name because I saw a standard name > platform_zenith_angle which can be applied to satellite zenith angles > and thought to complete the other two missing: satellite scan/look > angle and satellite azimuth angle by replacing "satellite" with > "platform". > > -Aleksandar > > > On Mon, Jan 14, 2013 at 12:29 PM, John Graybeal <[email protected]> wrote: >> I agree with Bruno -- platform angle as it is defined in the request is the >> angle of the _platform_ with respect to a reference direction ("the >> horizontal angle between the line of sight from the observation point to the >> platform and a reference direction at the observation point, which is often >> due north"). The seems like platform orientation to me too. >> >> I wasn't excited about the name platform_azimuth_angle anyway, because it is >> ambiguous on this exact point -- is it the azimuth angle of the platform, or >> of the instrument on the platform? (the former, in this case). >> Platform_orientation seems to be the accepted name for the purpose. >> >> The definition is very weak though -- can we propose the substitution of >> this definition for that one? >> >> John >> >> On Jan 14, 2013, at 09:17, Bruno PIGUET wrote: >> >>> Le 14/01/2013 17:21, Aleksandar Jelenak - NOAA Affiliate a écrit : >>>> Dear Bruno, >>>> >>>> On Fri, Jan 11, 2013 at 11:52 AM, Bruno PIGUET <[email protected]> >>>> wrote: >>>>> I have one remark about "platform_azimuth_angle" >>>>> >>>>> I like this name and it correspond to usual navigation definition (as >>>>> far as I can tell from my experience with airborne and shipborne >>>>> measurements), but... >>>>> >>>>> There is already a standard name called "platform_orientation", whose >>>>> definition seems to be the same, even if less precisely-worded : The >>>>> platform orientation is the direction in which the "front" or >>>>> longitudinal axis of the platform is pointing (not necessarily the same >>>>> as the direction in which it is travelling, called platform_course). >>>> >>>> platform_orientation is not the same as platform_azimuth_angle. This >>>> azimuth angle is related to measurements made by an instrument mounted >>>> on a platform (satellite, ship, airplane, truck, etc.). >>> >>> Sorry for looking dumb, but I don't see the difference (except that >>> "platform_orientation" is not precisely defined). >>> >>> I'm currently producing CF files containing airborne measurements, >>> and the parameter which is usually called "heading", which is in fact >>> exactly defined as "platform_azimuth_angle", is qualified with >>> "standard_name = platform orientation". >>> >>> Bruno. >>> -- >>> [email protected] >>> Équipe GMEI/TRAMM >>> CNRM-GAME : UMR Meteo-France/CNRS n°3589 >>> _______________________________________________ >>> CF-metadata mailing list >>> [email protected] >>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata >>> >> >> >> ---------------- >> John Graybeal <mailto:[email protected]> phone: 858-534-2162 >> Product Manager >> Ocean Observatories Initiative Cyberinfrastructure Project: >> http://ci.oceanobservatories.org >> Marine Metadata Interoperability Project: http://marinemetadata.org >> >> >> >> >> >> >> >> _______________________________________________ >> CF-metadata mailing list >> [email protected] >> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > _______________________________________________ > CF-metadata mailing list > [email protected] > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata -- [email protected] Équipe GMEI/TRAMM CNRM-GAME : UMR Meteo-France/CNRS n°3589 _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
