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I'm Qgis user from Czech Republic. We have a spatial national coordination system (Krovak system) having positive X axes pointing to the south and positive Y axes to the west. Many geographical systems have problem to display such coordination system, so usually is used transformation which gives:

X_transformed = - Y_Krovak Y_transormed = - X_Krovak The above described transformed coordination system is described in EPSG database as EPSG: 102067

To my sadness this projection was excluded from Qgis projection database starting Qgis 1.7.4. Many Czech wms servers work with this projection and I need their data. Many GIS projects are accomodated into this transformed coordination system.

To bring EPSG 102067 projection into my QGis 1.8 I override its original projection database file which is distributed with projection database file of Qgis 1.7.3 (including EPSG 102067 projection). Name of this file is srs.db

My problem is that I can not correctly geoference raster map into EPSG 102067 projection system. Above mentioned information possible could be part of the problem, or absolutely not. My attempts are resulting into georefferenced raster having height and width less than 1 meter.

Georeference points and original bmp raster could be downloaded form http://www.1progeo.cz/download.php

Login: qgis Password: qgis

as a zip archive so to debug my mistake could be quite easy. Would you be so kind to help me to give me guidence how to georeference raster map correctly?

Thank you very much.

With best regards

Jan

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102067 isn't EPSG, but ESRI. EPSG did just add these: 5514 (Greenwich-based, East/North axes) and 5221 (Ferro-based, East/North axes), about a year and 4 months ago. They technically use a new implementation of Krovak projection so that may not have been added to PROJ.4, etc yet. – mkennedy Sep 17 '12 at 16:07
As you say, 102067 isn't an 'official' EPSG CRS. But to obtain data from Czech WMS servers there has to be a CRS named EPSG:102067 in the QGIS CRS database. User-defined CRSs don't work with WMS servers. N. – nhopton Sep 17 '12 at 16:38
@nhopton, thanks for the clarification! – mkennedy Sep 17 '12 at 17:59

1 Answer

up vote 3 down vote

All I can say Jan is that I had no problem georeferencing your map using the supplied GCPs (Ubuntu 12.04, QGIS Master, amd64).

In my case I didn't edit srs.db, I made a custom CRS instead:

+proj=krovak +lat_0=49.5 +lon_0=24.83333333333333 +alpha=0 +k=0.9999 +x_0=0 +y_0=0 +ellps=bessel +towgs84=570.8,85.7,462.8,4.998,1.587,5.261,3.56 +units=m +no_defs

The georeferencing method was Helmert Nearest neighbour. I've checked a few points on the map using the coordinate capture plug-in and Google Earth and they plot nicely.

The resulting GeoTIFF.

Best to download this by right-clicking on the link and going 'Save as..'. When you load the image QGIS might not recognise its CRS, in which case set the layer CRS manually.

Nick.

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Dear Nick,thank you very much for your prompt help. I will try achieve same result with the same georeference method and recognize the problem. Further I will post my experience. With best regrads Jan – Jan Sep 18 '12 at 9:10
Good evening Jan, could you let me have the URL for one of the WMS servers that won't work unless EPSG:102067 exists in the CRS database? N. – nhopton Sep 18 '12 at 19:20

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