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I am using QGIS. I would like to clip a raster precipitation layer using an admin boundary layer that is vector data. However the geoprocessing tools seem to be usable only for vector data.

How can I clip this precipitation layer?

  • Did you really mean for "vector" to appear twice in this question? – whuber May 23 '11 at 15:23
  • @whuber - not in particular...does it matter in this forum? – Kirk May 24 '11 at 15:05
  • I couldn't make sense of the question without changing one of the "vector" to "raster." I think I get it now: you are saying you think the geoprocessing tools are only applicable when all elements are vector data. The confusion was that you explicitly say the boundary layer is in vector format, and as that is the immediate precedent, it makes the question ambiguous. – whuber May 24 '11 at 15:19
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    I have the same problem as the original question - the clipping tool using the gdal plugin works, but it only clips in rectangles.....what if you need to clip it to something like a country border? – Matt Jun 14 '12 at 16:53
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Install the GDAL plugin and then use the Clipper Tool.
enter image description here

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    The "gdal tools" aka "raster tools" plugin is installed by default since qgis 1.5, if I'm not wrong. No need to install it manually. – Giovanni Manghi May 23 '11 at 18:57
  • I found that this tool adds a band to the raster. It uses the command dstalpha. – BWill May 31 '11 at 13:19
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    As Pablo has written, Clipper Tool is the answer. In qgis 1.7.0, the name of the plugin is "GdalTools". The tools (along with the "Clipper" we're looking for) are added to the Raster menu after enabling it with qgis plugin manager. – amp May 10 '12 at 7:43
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    Please not that raster and vector data must be saved on disk in the same CRS. Simple png files and delimited text layers with CRS set in QGIS will not work. – AndreJ Dec 14 '13 at 15:56
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If you are interested using Python, a good documentation is available at GeospatialPython.com, here.

and clipraster.py source is here.

clipping

The Process:

Clipping a raster is a series of simple button clicks in high-end geospatial software packages. In terms of computing, geospatial images are actually very large, multi-dimensional arrays. Remote Sensing at its simplest is performing mathematical operations on these arrays to extract information from the data. Behind the scenes here is what the software is doing (give or take a few steps):

  1. Convert the vector shapefile to a matrix which can be used as mask
  2. Load the geospatial image into a matrix
  3. Throw out any image cells outside of the shapefile extent
  4. Set all values outside the shapefile boundary to NODATA (null) values
  5. OPTIONAL: Perform a histogram stretch on the image for better visualization
  6. Save the resulting image as a new raster.
7

I'd recommend using gdalwarp as you can increase the efficiency of the process.

For example, if you want to cut a raster inraster.tif with a shapefile extent.shp:

gdalwarp -cutline extent.shp -crop_to_cutline -of GTiff  -dstnodata 255 inraster.tif inraster_cropped.tif -co COMPRESS=LZW -co TILED=YES --config GDAL_CACHEMAX 2048 -multi

The last two parameters allows you to boost the process using:

  1. A multicore implementation.
  2. Setting the cache available to the function.
1

I'm not sure of how to do it in QGIS, however you may use another open source GIS software such as GRASS or GDALWarp to clip your raster. See keymirror and geographika answers below.

For an ArcGIS Desktop based solution, you may want to have a look at Clipping a raster using a polyline or polygon

protected by Community Jun 14 '12 at 18:03

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