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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link=blue vlink=purple><div class=WordSection1><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Hello All,<o:p></o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>I am new to the world of PostGIS and GDAL, but I’m looking for some help.<o:p></o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>I've researched and it appears that gdalbuildvrt is supposed to be able to <o:p></o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>resolve overlap areas when “no data values” are defined for the sources, <o:p></o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>but I am unable to produce the expected results. Where elevation raster <o:p></o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>values exist in the overlap areas, the values on both tiles are the same,<o:p></o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>so I have no need for a computational mosaic, simply a merge of the data<o:p></o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>which pays no attention to “no data” in either source raster.<o:p></o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>I've tried the following workflow:<o:p></o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1. Set No data values to -999<o:p></o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>gdal_translate -ot float32 -of gtiff -a_nodata -999 in_original.tif <o:p></o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>out_nodata_defined.tif<o:p></o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>2. Build VRT with specified source no data value<o:p></o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>gdalbuildvrt -srcnodata -999 -hidenodata out.vrt <o:p></o:p></span></p><p class=MsoPlainText><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>out_nodata_defined.tif<o:p></o:p></span></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoNormal>Am I doing something wrong?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><b><u><span style='color:black'><a href="http://www.unb.ca/fredericton/forestry/people/ogilvie.html"><span style='color:black'>Jae Ogilvie, Research Associate</span></a><o:p></o:p></span></u></b></p><p class=MsoNormal><span style='font-size:10.0pt'>Faculty of Forestry & Environmental Management<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt'>University of New Brunswick<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt'>28 Dineen Drive<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt'>Fredericton, NB<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt'>Canada E3B 6C2<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt'>Tel. 506 451 6823 Fax. 506 453 3538<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt'>Web <span style='color:black'><a href="http://watershed.for.unb.ca/"><span style='color:black'>http://watershed.for.unb.ca/</span></a></span><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt'><o:p> </o:p></span></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><i><span style='font-size:10.0pt'>This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail.<o:p></o:p></span></i></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>