Re: [OpenMap Users] Constants in Geo.java

I think I'd go with the WGS 84 numbers, then, as Todd referenced:

WGS84 values: 6378137.0 m, 1/f=298.257223563

That's what we have in the OpenMap Plant.java class. I can make those
changes to the OpenMap version that's checked in now, but I know we've
been talking about including other evolving versions of Geo and it's
partner classes into the OpenMap codebase.

Thanks, Ken.

- Don

On May 12, 2004, at 4:28 PM, Ken Anderson wrote:

> I think i took these numbers from there because they looked
> authritative.
> I'll be glad to use numbers you consider better if you can point me to
> them.
>
> At 04:18 PM 5/12/2004 -0400, Don Dietrick wrote:
>> Hi Todd,
>>
>> The code references
>> http://www.gfy.ku.dk/%7Eiag/HB2000/part4/groten.htm, which lists
>> these numbers as
>>
>> Equatorial radius of the Reference Ellipsoid (mean equatorial radius
>> of the Earth) in the zero-frequency tide system (Bursa et al. 1998)
>> (6378.13662 KM)
>>
>> and
>>
>> Polar flattening computed in the zero-frequency tide system, (adopted
>> GM, w , and J2 in the zero-frequency tide system) (298.25642).
>>
>> Seems like this is a different datum than WGS 84 and my impression is
>> that these should be changed in the OpenMap Geo class to match WGS
>> 84, or at least be settable.
>>
>> Ken, comments? I just don't know the background of your choosing
>> those values.
>>
>> - Don
>>
>>
>> On May 12, 2004, at 3:53 PM, Webb, Todd wrote:
>>
>>> I am trying to track down some discrepancies between calculations in
>>> our mapping framework and OpenMap. For coordinate calculations
>>> there are some constants defined in Geo.java for Ellipsoid
>>> semi-major axis and flattening reciprocal. These numbers differ
>>> slightly from WGS84, does anyone know where they came from?
>>>
>>> Geo.java: 6378.13662 km, 1/f=298.25642
>>>
>>> Thanks,
>>> Todd
>>>
>>> Todd A Webb <twebb@titan.com>
>>> The Titan Corporation
>>> 3033 Science Park Road
>>> San Diego, CA 92121
>>> 858.597.9128
>>> --
>>> [To unsubscribe to this list send an email to "majdart@bbn.com"
>>> with the following text in the BODY of the message "unsubscribe
>>> openmap-users"]
>>>
>>
>>
>> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>> Don Dietrick, dietrick@bbn.com
>> BBN Technologies, Cambridge, MA
>> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>
> --
> [To unsubscribe to this list send an email to "majdart@bbn.com"
> with the following text in the BODY of the message "unsubscribe
> openmap-users"]
>
>

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Don Dietrick, dietrick@bbn.com
BBN Technologies, Cambridge, MA
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

--
[To unsubscribe to this list send an email to "majdart@bbn.com"
with the following text in the BODY of the message "unsubscribe openmap-users"]