Concur with all.
On Jan 17, 2013, at 09:00, Bruno PIGUET wrote:
> Le 15/01/2013 20:23, John Graybeal a ?crit :
>> Bruno,
>>
>> Given solar_azimuth_angle parallels this definition pretty closely, would you be OK with the originally proposed name if the definition is clear?
>
> First, I apologize for not beeing able to answer yesterday.
>
> It is true if you explain "platform_azimuth_angle" by giving the
> analogue of "solar_azimuth_angle", things become clear.
>
> But I whish to remind that there are contexts where the word
> "azimuth" is defined as the quantity also named "yaw". Cf. my old
> message
> http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2008/052686.html where
> I explained that in some books, the angle between the platform axis and
> a fixed direction is called Azimuth, and noted Psi, and it is
> acknowledged that it is sometimes called the yaw angle.
>
> For CF, I would propose to stick to one definition of azimuth, which
> will be repeated every in all definition where it appears (as it is
> commonly done in the cf-standard-name-table).
> I propose : Azimuth is the angle between a reference direction
> (usually the North) and the projection on a reference plane (usually the
> local horizon) of a vector from an specific location to a point of interest.
>
> Your opinion ?
>
> Bruno.
>
>>
>> john
>>
>> On Jan 15, 2013, at 09:28, Bruno PIGUET wrote:
>>
>>> 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 ?crit :
>>>> 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 <jgraybeal at ucsd.edu> 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 ?crit :
>>>>>>> Dear Bruno,
>>>>>>>
>>>>>>> On Fri, Jan 11, 2013 at 11:52 AM, Bruno PIGUET <bruno.piguet at meteo.fr> 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.
>>>>>> --
>>>>>> bruno.piguet at meteo.fr
>>>>>> ?quipe GMEI/TRAMM
>>>>>> CNRM-GAME : UMR Meteo-France/CNRS n?3589
>>>>>> _______________________________________________
>>>>>> CF-metadata mailing list
>>>>>> CF-metadata at cgd.ucar.edu
>>>>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>>>>>>
>>>>>
>>>>>
>>>>> ----------------
>>>>> John Graybeal <mailto:jgraybeal at ucsd.edu> 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
>>>>> CF-metadata at cgd.ucar.edu
>>>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>>>> _______________________________________________
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>>>> CF-metadata at cgd.ucar.edu
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>>> --
>>> bruno.piguet at meteo.fr
>>> ?quipe GMEI/TRAMM
>>> CNRM-GAME : UMR Meteo-France/CNRS n?3589
>>> _______________________________________________
>>> CF-metadata mailing list
>>> CF-metadata at cgd.ucar.edu
>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>>
>>
>> ----------------
>> John Graybeal <mailto:jgraybeal at ucsd.edu> phone: 858-534-2162
>> Product Manager
>> Ocean Observatories Initiative Cyberinfrastructure Project: http://ci.oceanobservatories.org
>> Marine Metadata Interoperability Project: http://marinemetadata.org
>>
>>
>>
>>
>>
>>
>>
>>
>
----------------
John Graybeal <mailto:jgraybeal at ucsd.edu> phone: 858-534-2162
Product Manager
Ocean Observatories Initiative Cyberinfrastructure Project:
http://ci.oceanobservatories.org
Marine Metadata Interoperability Project:
http://marinemetadata.org
Received on Thu Jan 17 2013 - 11:11:28 GMT
