I have found the +towgs84 parameters on <a href="http://www.geocities.com/mapref/mapref.html">http://www.geocities.com/mapref/mapref.html</a>. <br>I have modified the lambert 72 definition to : "+proj=lcc +lat_1=51.16666723333333
+lat_2=49.8333339 +lat_0=90 +lon_0=4.367486666666666 +x_0=150000.013 +y_0=5400088.438 +ellps=intl +towgs84=-99.059,53.322,-112.485,-0.419,0.830,-1.885,-1.0 +units=m +no_defs no_defs <>"<br>The result are better but not good : I always have a difference of 80 meters
<br><br><div><span class="gmail_quote">2006/8/8, Eric Miller <<a href="mailto:EMiller@dfg.ca.gov">EMiller@dfg.ca.gov</a>>:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
I think you need some datum transformation parameters on your Lambert<br>projection. See the +towgs84 parameter. The EPSG database doesn't seem<br>to have any datum transformation information for that coordinate system.
<br> So, that may be the best you can expect...<br><br>>>> <a href="mailto:gheysen.t@gmail.com">gheysen.t@gmail.com</a> 8/8/2006 1:12:53 AM >>><br>Finally, I use the solution of changing the PROJ_LIB environment
<br>variable<br>when my VB program start. I can now call the projection function<br>(pjTransform) but the result are bad. I have a gap of about 100 meters<br>between the real position and the projected coordinates.<br>My aim is to project WGS 84 coordinates from garmin GPS to various
<br>european<br>state coordinates. This is my first attempt to use proj4 and I don't<br>know<br>what I do wrong.<br>Here is the definition I use :<br>WGS 84 (epsg : 4326) : +proj=longlat +ellps=WGS84 +datum=WGS84<br>+no_defs
<br>no_defs <><br>Lambert 72 Belge (epsg : 31370) : +proj=lcc +lat_1=51.16666723333333<br>+lat_2=<br>49.8333339 +lat_0=90 +lon_0=4.367486666666666 +x_0=150000.013 +y_0=<br>5400088.438 +ellps=intl +units=m +no_defs no_defs <>
<br><br>Someone can help me ?<br><br>2006/8/1, Eric Miller <<a href="mailto:EMiller@dfg.ca.gov">EMiller@dfg.ca.gov</a>>:<br>><br>> That VB wrapper hasn't been updated to know about the<br>> pj_set_searchpath() function. I'm not sure if the pj_set_finder()
<br>> function will work. You could try it. See the AddressOf operator.<br>I<br>> seem to recall it doesn't work due to calling convention issues.<br>><br>> If you can figure out how to change the PROJ_LIB environment
<br>variable<br>> from within your VB program, that should work. Just do it during<br>> program startup before any proj.4 functions are called. Or, maybe,<br>use a<br>> batch file that launches your VB program and sets the PROJ_LIB
<br>> variable?<br>><br>> >>> <a href="mailto:gheysen.t@gmail.com">gheysen.t@gmail.com</a> 8/1/2006 1:19:04 AM >>><br>> Hello,<br>><br>> I have wrote a little program in vb to download and upload GPS data.
<br>> This<br>> software use 2 specific functions to transform the data from WGS 84<br>to<br>> Lambert 72 (Belgium) and from Lambert 72 to WGS 84. I want to<br>replace<br>> these<br>> functions by the proj.4
vb wrapper so I can use this software in<br>other<br>> contry than Belgium. I have test, without problem, this wrapper with<br>> the<br>> file "exemple.mdb".<br>><br>> My problem is that I have Qgis installed and thus I have already a
<br>> "Proj_lib" environment variable. If user uninstall Qgis, the proj.4<br>is<br>> uninstall. How can I have two versions of Proj.4 install on the same<br>> computer. I have read than I can use pj_set_finder() or
<br>> pj_set_searchpath()<br>> to override this environment variable. This function is it available<br>> through<br>> the vb wrapper ? If yes, how can I use this in vb ?<br>><br>> Thanks in advance.<br>>
<br>> Gheysen Thibaut.<br>> _______________________________________________<br>> Proj mailing list<br>> <a href="mailto:Proj@lists.maptools.org">Proj@lists.maptools.org</a><br>> <a href="http://lists.maptools.org/mailman/listinfo/proj">
http://lists.maptools.org/mailman/listinfo/proj</a><br>><br>_______________________________________________<br>Proj mailing list<br><a href="mailto:Proj@lists.maptools.org">Proj@lists.maptools.org</a><br><a href="http://lists.maptools.org/mailman/listinfo/proj">
http://lists.maptools.org/mailman/listinfo/proj</a><br></blockquote></div><br>