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Every time I try to save a layer with a new projection using 'save as' my QGIS crashes. The new files are there but they seem false. Please see two screenshots attached, one before and one after I used 'save as'. I also included a screenshot of my 'save as' page. My new projection is supposed to be centered around lat 70° but it does not seem that way. In Addition about 10 rows of data (in the form of rectangles in the screenshot and rows in my attribute table) are missing.

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Please note this is also a screenshot of the areas when i changed the project projection to my custom projection, the areas still look off:

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I seem to be loosing data when clipping my shape file at 89.9°.

To do this I created a new vector layer to use as a clip layer with an upper limit at 89.9°. I imported it and used the function: Vector --> geoprocessing tools --> clip. Here is a screenshot of what I entered into this function. Any ideas what I could be doing wrong? P.s. There is no 'processing completed' message at the end of this it appears to get stuck in the clipping process.

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anina
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  • I found a link with a similar problem: https://github.com/mapbox/geojson.io/issues/365. You can try to use ogr2ogr for reprojecting your data (ogr2ogr -t_srs "+proj=laea +lat_0=70 +lon_0=0 +x_0=0 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs" output.shp input.shp and see if it works. If not, you can try to rebuild your shapefile by exporting it in GeoJSON, uploading to geeojson.io and downloading it as a shapefile or using GRASS's v.build (only in GRASS). There are several other data exchange solutions available (KML, GML), you can try them, too. – Gabor Farkas Sep 27 '14 at 15:15
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    Did you folow my advice to cut the EPSG:4326 shapefile at 89.9° North? The points at the 90° North line will all fall into one point (the North pole). That might break the polygon definition. – AndreJ Sep 27 '14 at 17:19
  • Thanks @AndreJoost I just clipped my WGS84 vector layer and saved as my new custom proj. It did not crash my system and the map looks right so this must have been the problem! However now my attribute table is empty and In the metadata tab it does not show up the extents of the layer. See below: In layer spatial reference system units unknown extent Layer Spatial Reference System +proj=laea +lat_0=70 +lon_0=0 +x_0=0 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs –. I have edited my clipping method into the question. This is where the problem is. – anina Sep 28 '14 at 10:03
  • The cliplayer should be clip layer ;-) and the ICES_Area the input layer. – AndreJ Sep 28 '14 at 19:52
  • okayyyyy duh thanks @AndreJoost . This seems to have worked. My extents are different to what you said they should be for Lambert centered at 70N but I am assuming that is because I am working with these specific areas not the world? This is what I havein my metadata. How do I know if this is correct? Extents In layer spatial reference system units xMin,yMin -3685610.53,-3707057.72 : xMax,yMax 2075705.63,2218572.35 Layer Spatial Reference System +proj=laea +lat_0=70 +lon_0=0 +x_0=0 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs – anina Sep 29 '14 at 08:14

1 Answers1

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It helps if you cut your EPSG:4326 shapefile at 89.9° North.

The points at the 90° North line will all fall into one point (the North pole). That might break the polygon definition after reprojection.

In your screenshot, you have swapped input layer and clip layer. Therefore you get only the attributes form the cliplayer (presumably nothing).

To check the extent values, you can write them in a text file:

Name,X,Y
xMinyMin,-3685610.53,-3707057.72
xMaxyMax,2075705.63,2218572.35
xMinyMax,-3685610.53,2218572.35
xMaxyMin,2075705.63,-3707057.72

and add that as delimited text in your laea projection with these settings:

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Make sure that Settings -> Options, CRS tab, CRS for new layers is set to Prompt for CRS.

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Note that the extent in laea is not simply the reprojection of the corners from degree to laea (which I did in a previous comment).

AndreJ
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  • thank you for your help. im sorry but i am having trouble setting the format of delimited text so that my qgis recognizes it. I have tried saving in UCF16 and separating the values with new columns. Is there any other way to check that the projection has been successfully converted? @AndreJoost – anina Sep 30 '14 at 10:26
  • I added my import screen. If you are on Mac, see http://gis.stackexchange.com/questions/73961/how-to-add-csv-file-in-qgis-2-0-using-delimited-text-layer-plugin and http://hub.qgis.org/issues/8421 – AndreJ Sep 30 '14 at 15:30