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<div>Cleo,</div>
<div><br>
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<div>If I understand correctly you have latitude, longitude, elevation (considered as heigth above ellipsoid) and geoid (considered as height above geoid).</div>
<div>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.</div>
<div>The elevation above ellipsoid will change because of the change of ellipsoid dimensions.</div>
<div><br>
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<div>Alain</div>
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<div>Le 20 août 2014 à 01:29, Cleo Drakos <<a href="mailto:cleo21drakos@gmail.com">cleo21drakos@gmail.com</a>> a écrit :</div>
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<div dir="ltr">Dear Noel
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<div>Thanks for your explanation. So it means that <font face="arial, sans-serif">both ellipsoids have the same geocentric coordinates, and I can use Jose's instruction.</font></div>
<div><font face="arial, sans-serif">I have four columns (lats, lons, elevation, and geoid) in an ASCII file. I need to convert all these four parameters into WGS84 system.</font></div>
<div><font face="arial, sans-serif">How can I apply Jose's instruction? I mean how can I call c</font><span style="font-family:arial,sans-serif;font-size:13px">s2cs for different parameters? I did not know how to input these four parameters.</span></div>
<div><span style="font-family:arial,sans-serif;font-size:13px"><br>
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<div><span style="font-family:arial,sans-serif;font-size:13px">Sorry for this type of question, I hope you do not mind.</span></div>
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<div dir="ltr">cleo</div>
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<div class="gmail_quote">On Tue, Aug 19, 2014 at 8:44 PM, Noel Zinn (cc) <span dir="ltr">
<<a href="mailto:ndzinn@comcast.net" target="_blank">ndzinn@comcast.net</a>></span> wrote:<br>
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<div>Cleo,</div>
<div> </div>
<div>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
<a href="http://top2wgs.pro/" target="_blank">top2wgs.pro</a> that solves your problem. The program assumes dX = dY = dZ = 0. I’ve made the same assumption myself with
<font face="Times New Roman"><font face="Calibri">TOPEX/Poseidon in a different context. Then follow Jose’s cs2cs instructions.</font></font></div>
<div> </div>
<div>Thanks for the link.</div>
<div class="">
<div> </div>
<div>Noel</div>
<div> </div>
<div style="font-size: 12pt; font-family: Calibri; ">Noel Zinn, Principal, Hydrometronics LLC<br>
<a href="tel:%2B1-832-539-1472" value="+18325391472" target="_blank">+1-832-539-1472</a> (office),
<a href="tel:%2B1-281-221-0051" value="+12812210051" target="_blank">+1-281-221-0051</a> (cell)<br>
<a href="mailto:noel.zinn@hydrometronics.com" target="_blank">noel.zinn@hydrometronics.com</a> (email)<br>
<a href="http://www.hydrometronics.com/" target="_blank">http://www.hydrometronics.com</a> (website)<br>
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<div><b>From:</b> <a title="cleo21drakos@gmail.com" href="mailto:cleo21drakos@gmail.com" target="_blank">
Cleo Drakos</a> </div>
<div><b>Sent:</b> Tuesday, August 19, 2014 3:39 AM</div>
<div><b>To:</b> <a title="proj@lists.maptools.org" href="mailto:proj@lists.maptools.org" target="_blank">
PROJ.4 and general Projections Discussions</a> </div>
<div><b>Subject:</b> Re: [Proj] Can I convert the ellipsoids using Proj?</div>
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<div dir="ltr">Dear Jose<br>
<br>
Thanks for your answer. Can you help me how can I make certain that both ellepsoids have the same geocentric coordinates.<br>
Only the information I am having is below under the section of How does the GLAS ellipsoid compare with WGS 84?<br>
<br>
<div><a href="http://nsidc.org/data/icesat/faq.html#3_all" target="_blank">http://nsidc.org/data/icesat/faq.html#3_all</a>
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<div dir="ltr">cleo</div>
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<div class="gmail_quote">On Tue, Aug 19, 2014 at 6:03 AM, Jose Gonçalves <span dir="ltr">
<<a href="mailto:jagoncal@gmail.com" target="_blank">jagoncal@gmail.com</a>></span> wrote:<br>
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<div>Cleo<br>
<br>
If cartesian geocentric coordinates are the same and you just want to express them in a different ellipsoid you can do:<br>
<br>
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<br>
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<div>If there are shift and rotation you can express them in the +towgs84.<br>
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<div><br>
Regards<br>
<br>
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<div>José <br>
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<div class="gmail_quote">2014-08-18 15:13 GMT+01:00 Cleo Drakos <span dir="ltr"><<a href="mailto:cleo21drakos@gmail.com" target="_blank">cleo21drakos@gmail.com</a>></span>:<br>
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<div style="FONT-SIZE:13px;FONT-FAMILY:arial,sans-serif">Dear guys,</div>
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<div style="FONT-SIZE:13px;FONT-FAMILY:arial,sans-serif">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.</div>
<div style="FONT-SIZE:13px;FONT-FAMILY:arial,sans-serif"> </div>
<div style="FONT-SIZE:13px;FONT-FAMILY:arial,sans-serif">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.</div>
<div style="FONT-SIZE:13px;FONT-FAMILY:arial,sans-serif"> </div>
<div style="FONT-SIZE:13px;FONT-FAMILY:arial,sans-serif">Can I convert the ellipsoids using Proj?</div>
<div style="FONT-SIZE:13px;FONT-FAMILY:arial,sans-serif"> </div>
<span style="FONT-SIZE:13px;FONT-FAMILY:arial,sans-serif">I hope some of you can help me.</span><span><font color="#888888"><br>
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<div dir="ltr">cleo</div>
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