<div>Hi Andrew,</div>
<div> </div>
<div>you are right, in the most cases the GDAL utilities work well, and I've also use the GDAL utilities for a long time, especially the FWTools made by Frank, we should all thank Frank for such a wonderful GIS toolkit.</div>
<div> </div>
<div>I've check again and again with the GDALWARP, but things are not going in the right way. I am trying to translate the TIF images from the coordinate system CH1903 (Swiss National System) to ETRS89 / UTM ZONE 32N, and there are always some displacement with the base maps, I am sure that the base map and the original coordinate info for the TIF is correct. and here is an example:
</div>
<div> </div>
<div>(the transforming process is : CH1903 -> WGS84 -> ETRS89 / UTM ZONE 32N)</div>
<div> </div>
<div>the TIF image coordinate Info (*.tif): (Swiss National System)</div>
<div> 0.500000<br> 0.000000<br> 0.000000<br> -0.500000<br> 598125.250000<br>199999.750000</div>
<div> </div>
<div>If I transform the coordinate to WGS84 with GDAL, the value is:</div>
<div> </div>
<div>0.0000059839<br>0.0000000000<br>0.0000000000<br>-0.0000059839<br>7.4149523128<br>46.9529994915</div>
<div> </div>
<div>but the lon/lat of the upper left corner should be:</div>
<div> </div>
<div>7.41401039348263<br>46.9510762167473</div>
<div> </div>
<div>I would say that this is already big difference, because If I use this lon/lat to get the UTM coordinate, this small difference will be propagated, and will cause a displacement about hundreds meters.</div>
<div> </div>
<div>I am trying to find the source code, which does this coordinate transformation, so that I can check if the transformation parameters are correct, but unfortunately I can not find the source for this.</div>
<div> </div>
<div> </div>
<div>If someone has done something similar, please point me out how to fix this problem, especially the GIS people in Switzerland. I would really appreciate it.</div>
<div> </div>
<div>zhonghai<br> </div>
<div><span class="gmail_quote">On 7/14/06, <b class="gmail_sendername">Andrew Williams</b> <<a href="mailto:awilliams@rapidmap.com.au">awilliams@rapidmap.com.au</a>> wrote:</span>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">zhonghai,<br>I've litterally translated hundereds of TIF's from all over the world from multiple projections to multiple projections. I have also had "failures". However, in every case, it was either my fault in specifying the -s_srs or -t_srs. In some cases the fault lay in the original image. The TIFF itself was supplied with incorrect georefernceing information and so it was never going to work.
<br><br>Have you got a dump from GDALINFO that we can see and the GDALwarp command line you've used?<br><br>regards<br>Andrew<br><br> -----Original Message-----<br> From: Zhonghai Wang [mailto:<a href="mailto:zhonghaiw@gmail.com">
zhonghaiw@gmail.com</a>]<br> Sent: Fri 7/14/2006 12:14 AM<br> To: <a href="mailto:gdal-dev@lists.maptools.org">gdal-dev@lists.maptools.org</a><br> Cc:<br> Subject: [Gdal-dev] need tools for TIF image reprojection
<br><br><br> Hi guys,<br><br> I need a tool to reproject my TIF images, either free or non-free software.<br> I've tried with the GDAL utilities, sure I can do the reprojection, but the coordinates seems not correct, there are serveral hundert meters displacement according to the my base maps.
<br><br> thanks for your info.<br><br> zhonghai<br><br><br><br></blockquote></div><br>