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<br><div><div>On Feb 11, 2011, at 10:20 AM, Adam Dershowitz, Ph.D., P.E. wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">I am having a problem trying to use gdalwarp. Perhaps I am just missing something, but I figured I would see if someone can help. <div><br></div><div>I downloaded some aerial imagery from here:<br><a href="http://www.michigan.gov/dnr/0,1607,7-153-10371_14546-30211--,00.html">http://www.michigan.gov/dnr/0,1607,7-153-10371_14546-30211--,00.html</a><br><br>I want to import it into a UTM zone 17 project. So I did the following:<br>gdalwarp -t_srs '+proj=utm +zone=17 +datum=WGS84' input.sid output_utm.sid<br><br>gdapwarp responds with an error, but then continues with the conversion:<br>ERROR 6: Failed to initialize PROJ.4 with `+proj=omerc +lat_0=0 +lonc=0 +alpha=0 +k=1 +x_0=0 +y_0=0 +ellps=GRS80 +datum=NAD83 +units=m +no_defs '.<br>lat_0 = 0 or 90 or alpha = 90<br>0...10...20...30...40...50...60...70...80...90...100 - done.<br><div><br></div><div>It does complete, but the area of interest is in the range of UTM (254500,4734000) and the output of gdalwarp is around 663144,240035. </div><div><br></div><div>Any suggestions for what I might be doing wrong? </div><div><br></div><div><br></div><div>If I do gdalinfo on the original file here is what I get:</div><div><br></div><div><br></div><div>
<br></div></div></div></blockquote></div><br><div><br></div><div><div>I googled around some and it looks like this is actually an issue with the Michigan projection in Proj4. </div><div><br></div><div>I found this link:</div><div><a href="http://www.osgeo.org/pipermail/mapserver-users/2006-July/018292.html">http://www.osgeo.org/pipermail/mapserver-users/2006-July/018292.html</a></div><div><br></div><div>And this seems to give reasonable results, based on the above:</div><div><br></div><div>gdalwarp -t_srs '+proj=utm +zone=17 +datum=WGS84' -s_srs '+proj=omerc +lat_0=45.309166667 +lonc=-86.0 +alpha=337.255555556 +k=0.9996 +x_0=499839.8337 +y_0=528600.2398 +ellps=GRS80 +datum=NAD83 +units=m' oakgrove_sw.sid oakgrove_sw_utm.tifg</div></div><div><br></div><div>So, I am not really sure about the source of these numbers, but it does look pretty close.</div><div><br></div><div>--Adam</div></body></html>