[Proj] Can I convert the ellipsoids using Proj?

[Cleo Drakos]

Dear Noel and Alain

Thanks for your nice answers.

So, while calling the cs2cs, where can I input the lat, lon and elevation?

cs2cs -f %.9f +a=6378136.30 +rf=298.257 +proj=latlong +towgs84=0,0,0 +to
+a=6378137 +rf=298.25722356 +proj=latlong +towgs84=0,0,0

cleo


On Wed, Aug 20, 2014 at 3:37 PM, Alain Orsoni <Alain.Orsoni at ign.fr> wrote:

>  Cleo,
>
>  If I understand correctly you have latitude, longitude, elevation
> (considered as heigth above ellipsoid) and geoid (considered as height
> above geoid).
> If so, you have to input only latitude longitude and elevation in proj4.
> Heigth above geoid remains the same whatever the ellipsoid you use, it is
> just the height of the geoid above the ellipsoid which changes when you
> change ellipsoid.
> The elevation above ellipsoid will change because of the change of
> ellipsoid dimensions.
>
>  Alain
>
>
>  Le 20 août 2014 à 01:29, Cleo Drakos <cleo21drakos at gmail.com> a écrit :
>
>  Dear Noel
>
>  Thanks for your explanation. So it means that both ellipsoids have the
> same geocentric coordinates, and I can use Jose's instruction.
> I have four columns (lats, lons, elevation, and geoid) in an ASCII file. I
> need to convert all these four parameters into WGS84 system.
> How can I apply Jose's instruction? I mean how can I call cs2cs for
> different parameters? I did not know how to input these four parameters.
>
>  Sorry for this type of question, I hope you do not mind.
>
>
>  cleo
>
>
> On Tue, Aug 19, 2014 at 8:44 PM, Noel Zinn (cc) <ndzinn at comcast.net>
> wrote:
>
>>   Cleo,
>>
>> FAQ #7 under Altimetry products in the link you provide seems to answer
>> the question you ask.  The FTP link in that paragraph leads you to  a
>> program top2wgs.pro that solves your problem.  The program assumes dX =
>> dY = dZ = 0.  I’ve made the same assumption myself with TOPEX/Poseidon
>> in a different context.  Then follow Jose’s cs2cs instructions.
>>
>> Thanks for the link.
>>
>> Noel
>>
>> Noel Zinn, Principal, Hydrometronics LLC
>> +1-832-539-1472 (office), +1-281-221-0051 (cell)
>> noel.zinn at hydrometronics.com (email)
>> http://www.hydrometronics.com (website)
>>
>>  *From:* Cleo Drakos <cleo21drakos at gmail.com>
>> *Sent:* Tuesday, August 19, 2014 3:39 AM
>> *To:* PROJ.4 and general Projections Discussions
>> <proj at lists.maptools.org>
>> *Subject:* Re: [Proj] Can I convert the ellipsoids using Proj?
>>
>>   Dear Jose
>>
>> Thanks for your answer. Can you help me how can I make certain that both
>> ellepsoids have the same geocentric coordinates.
>> Only the information I am having is below under the section of How does
>> the GLAS ellipsoid compare with WGS 84?
>>
>> http://nsidc.org/data/icesat/faq.html#3_all
>>
>>
>>  cleo
>>
>>
>> On Tue, Aug 19, 2014 at 6:03 AM, Jose Gonçalves <jagoncal at gmail.com>
>> wrote:
>>
>>>  Cleo
>>>
>>> If cartesian geocentric coordinates are the same and you just want to
>>> express them in a different ellipsoid you can do:
>>>
>>> cs2cs -f %.9f +a=6378136.30 +rf=298.257 +proj=latlong +towgs84=0,0,0 +to
>>> +a=6378137 +rf=298.25722356 +proj=latlong +towgs84=0,0,0
>>>
>>>  If there are shift and rotation you can express them in the +towgs84.
>>>
>>> Regards
>>>
>>>  José
>>>
>>>
>>>
>>> 2014-08-18 15:13 GMT+01:00 Cleo Drakos <cleo21drakos at gmail.com>:
>>>
>>>>   Dear guys,
>>>>
>>>> I have the data (latitudes, longitudes, and elevations) given in
>>>> ICESat/GLAS ellipsoid. This equatorial radius and  reciprocal flattening
>>>> (1/f) on this ellipsoid are 6378136.30 m and is 298.257 respectively.
>>>>
>>>> Now, I want to convert my data into WGS84 ellepsoid with equatorial
>>>> radius and reciprocal flattening (1/f) of 6378137.000000 and 298.25722356
>>>> respectively.
>>>>
>>>> Can I convert the ellipsoids using Proj?
>>>>
>>>> I hope some of you can help me.
>>>>
>>>>  cleo
>>>>
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>>>
>>>
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>>
>>
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