<HTML dir=ltr><HEAD><TITLE>Re: [Gvsig_english] No problems reprojecting from GK to UTM usingBETA2007</TITLE>
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<DIV dir=ltr><FONT color=#000000 size=3 face="Times New Roman">Hello, Heinz:</FONT></DIV>
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<DIV dir=ltr><FONT color=#000000 size=3 face="Times New Roman">I have done the test you describe and indeed the points in the CSV file are not a subset of the GSB grid, but the error is almost zero. If we are honest, we'll have to look for an explanation, no? Here is my guess: the CSV file was created using the GSB grid. I misunderstood the goal of that verification file (perhaps the Australian file too?). They are not used to check if the grid works fine. They are used to check that your GIS software knows how to deal with the grid. This is my second hypothesis :-)</FONT></DIV>
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<DIV dir=ltr><FONT color=#000000 size=3 face="Times New Roman">As for the transformation with code 1780 available in gvSIG, I have used it and get the expected errors (< 5m):</FONT></DIV>
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<DIV dir=ltr><FONT color=#000000 size=3 face="Times New Roman">3.43 m</FONT></DIV>
<DIV dir=ltr><FONT color=#000000 size=3 face="Times New Roman">2.85 m</FONT></DIV>
<DIV dir=ltr><FONT color=#000000 size=3 face="Times New Roman">0.15 m</FONT></DIV>
<DIV dir=ltr><FONT color=#000000 size=3 face="Times New Roman">etc.</FONT></DIV>
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<DIV dir=ltr><FONT color=#000000 size=3 face="Times New Roman">Perhaps you have not chosen the right options? I have used gvSIG 1.1.2 because I am on Windows Vista.</FONT></DIV>
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<DIV dir=ltr><FONT color=#000000 size=3 face="Times New Roman">Regards,</FONT></DIV>
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<DIV><FONT size=2 face="Courier New"><FONT size=3 face="Times New Roman">Juan Lucas Domínguez Rubio<BR></FONT>---</FONT></DIV>
<DIV><FONT size=2 face="Courier New"><FONT size=2 face="Courier New"><FONT size=2 face="Courier New">Prodevelop SL, Valencia (España)</FONT></DIV>
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<DIV><FONT size=2 face="Courier New">Tlf.: 96.351.06.12 -- Fax: 96.351.09.68<BR></FONT><A href="http://www.prodevelop.es/"><FONT size=2 face="Courier New">http://www.prodevelop.es</FONT></A><BR><FONT size=2 face="Courier New">---</FONT></DIV></FONT></DIV></FONT></DIV>
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<FONT size=2><FONT face=Tahoma><B>> De:</B> gvsig_internacional-bounces@listserv.gva.es en nombre de Heinz Mundhenk<BR><B>> Enviado el:</B> jue 10/12/2009 18:07<BR><B>> Para:</B> gvsig_internacional@listserv.gva.es<BR><B>> Asunto:</B> Re: [Gvsig_english] No problems reprojecting from GK to UTM usingBETA2007<BR><STRONG>> </STRONG></FONT></FONT><BR></DIV>
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<P><FONT size=2><STRONG><FONT face=Tahoma>> </FONT></STRONG>Dear list,<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>here is another working grid-based reprojektion for Germany.<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>Reprojecting from GK to ETRS89/UTM using grid BETA2007<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>In the next years coordinates from different old SRS in<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>Germany will change to the new projection ETRS89/UTM<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>with EPSG:25832 (Westgermany) and 25833 (Eastgermany).<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>Most old SRS in former Westgermany are based on the Gauss-Krueger-<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>Projektion (GK, EPSG:31466, 31467 and 31468).<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>The transition from GK to UTM can be done with the integrated<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>"transformation on the fly" in gvSIG for errors lower than 5 meters.<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>If you use the grid "BETA2007.gsb", the error is lower than 1 meter.<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>Here you can get the grid and coordinates for a tests :<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG> www.crs-geo.eu/BeTA2007<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG> files BETA2007.gsb (85 kByte)<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG> BETA2007testdaten.csv (12 kByte)<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>On this website you find lots of additional informations.<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>For a test make a dfb-file from the csv-file by selecting all records<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG> with Quell-Bezugssystem (source) = DE_DHDN_3GK3<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG> and Ziel-Bezugssytem (target) = ETRS89_UTM32.<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>From this dbf-table create the shape (with testpoints)<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG> GK3_31467.shp using Quell-X and Quell-Y for X- and Y-coodinates.<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>How to integrate the *.gsb - file in gvSIG 1.9 ?<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>Make a view with SRS-property EPSG:25832 (ETRS89/UTM32) and add the<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>testpoint-shape with the SRS-Property EPSG:31467, using grid-transformation<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>(with german-program-surface/skin : NTv2 Format Raster- Datei).<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>In the next window click the button Import and select the<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>previous downloaded grid BETA2007.gsb.<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>Then Export the reprojected shape under the name UTM32_25832.shp and add it to<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>the view. Now you can add the fields X and Y and calculate x() and y().<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>Then calculate the difference between Ziel-X and X / Ziel-Y and y.<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>The Errors are lower 0.01 meters ! The testpoints are no grid-points !<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>Observations<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>1. The reprojektion with the grid does not work in the reverse order<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG> from UTM to GK.<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>2. Reprojection from GK to UTM with gvSIG using the same testpoint-shape<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG> and the integrated EPSG-transformations 1780 or 15948 result with<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG> errors between 100 and 200 meters ! Why ?<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>Greetings<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG><BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>Heinz Mundhenk<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG>hmundhenk@gmx.de<BR><STRONG><FONT face=Tahoma>> </FONT></STRONG></FONT></P></DIV></BODY></HTML>