Hi<br><br>On our proj4 installation you should have a directory call "nad". This directory have some dictionnary of projection that could be used to define projection parameters. For exemple with the lat/long wgs84 projection you could use <br>
<br> projPJ src= pj_init_plus( "+init=epsg:4326"); <br><br>see <a href="http://spatialreference.org/ref/epsg/4326">http://spatialreference.org/ref/epsg/4326</a> for searching your projection code.<br>Take care of setting the PROJ_LIB environnement variable to the correct path for your projection directory.<br>
<br>Nicolas<br><br><br><div class="gmail_quote">2012/10/4 Doanh Hoang <span dir="ltr"><<a href="mailto:doanh.hoang@mud-maps.com" target="_blank">doanh.hoang@mud-maps.com</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi all <br><br>Im developer and this is the first time I touch PROJ.4 . And I have following problem , please anyone can give me an advice:<br><br>In my project I need to do <b>transformation from datums (US, North America, UK, South Africa, New Zealand) to WGS84. </b><br>
<br>After having a look at defintion of pj_transform (function to do datums transformation on PROJ.4). I have seen that there are so many input parameters.<br> <br>For example : following code that I found in internet : <br>
------------------------------------------------------------------------------------------------------<br> projPJ src= pj_init_plus("+proj=tmerc +lat_0=38N +lon_0=128E +ellps=bessel +x_0=400000 +y_0=600000 +k=0.9999 +towgs84=-146.43,507.89,681.46");<br>
projPJ dst= pj_init_plus("+proj=latlong +datum=WGS84 +ellps=WGS84");<br> double x,y,z;<br> x=100;<br> y=100;<br> z=100;<br> pj_transform(src,dst,1,1,&x,&y,NULL);<br>------------------------------------------------------------------------------------------------------<br>
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<td style="min-height:15.0pt;width:640pt" height="15" width="640">params for initionlization of datums<br>+proj=merc
+ellps=clrk66 +lat_ts=33</td>
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<td style="min-height:15.0pt" height="15">+proj=latlong +ellps=clrk66</td>
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------------------------------------------------------------------------------------------------------<br>There are so many geospatial knowledge neccessary to understand these parameter. <br>Im developer and I know just only the simple name of datums(WGS84, NAD27, NAD83, etc,..) and coordinates of points, <br>
<br>With them how I can make transformation between different datums ? <b>Where I can get input parameters and define correct geospatial input parameters.</b><br><br>I very need your help. Thanks a lot. <br><span class="HOEnZb"><font color="#888888"><br>
Hoang Doanh<br>
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