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I'd need to reproject a raster dataset in a new customized projection, but I'm fairly new at both QGIS and GDAL and I'm not exactly sure about how to proceed and what the exact syntax is.

The starting raster dataset is in EPSG:3035 and I'd like to reproject it in a Lambert Conic Conformal projection of which I know center latitude, center longitude, true latitude 1, true latitude 2, standard longitude and pole latitude and longitude (the latter are standard: 90 and 0 degrees).

I guess that I should use "Raster"-->"Projection"-->"Reproject" under QGIS, but I'm not quite sure on how to express it in proj4 syntax.

Thanks for any help!

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You have to create a Settings -> Custom Coordinate System first.

For LCC, this looks like

+proj=lcc +lat_1=-18 +lat_2=-36 +lat_0=-25 +lon_0=135 +ellps=WGS84  +units=m +no_defs

center lat and lon go into lat_0 and lon_0, true lat 1 and 2 into lat_1 and lat_2.

I'm not sure where the others should go to. East and North are always positive, and don't use degrees-minutes-seconds format.

After you click the diskette symbol, you will find your custom CRS at the bottom of the CRS list.

  • The reprojection procedure completed without errors, but if I try to extract a fraction of the reprojected map using coordinate extremes coming from the model which actually used the custom projection, I receive an error about "falling outside the raster domain": what's the coordinate format? I used decimal degrees... – Mutewinter Sep 17 '13 at 14:57
  • You have to reproject your decimal degrees into the same custom projection. On-the-fly-reprojection does not work with raster calculations. – AndreJ Sep 17 '13 at 16:49
  • I realized I've not been clear: I've got a simulation which outputs data (included longitude and latitude) in the aforementioned Lambert Conformal projection. I want to reproject a map in qgis to that LCC so that I can extract the simulated area using the lat and long from the simulation. Therefore once the map is reprojected the decimal degrees should ALREADY be in that projection... – Mutewinter Sep 18 '13 at 8:31
  • Lat and long are always in (unprojected) degrees. A projected map (LCC or other) has metres or feet as units. The coordinates are called X and Y, or East and North, to avoid misunderstanding between the both worlds. – AndreJ Sep 18 '13 at 9:00
  • Ok, now it's quite clear! The thing is that the simulation does not output a map, just longitude and latitude data (along with map projection data like true lat, lon, etc.): is there a way to convert such longitude and latitude matrixes to X and Y coordinates? – Mutewinter Sep 18 '13 at 9:30

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