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I have a shapefile of el Congo River Basin dy area. Attributes information is just area. Actually I want create a mask with ones in the river basin and ceros outside to just used later in IDL or matlab a mask of the Congo. How can I built a proper mask file (1 inside the congo, o outside) using this shapefile in Arcgis or QGIS ?

I downloaded here: http://hydrosheds.cr.usgs.gov/datadownload.php?reqdata=30bass a shp from the rivers basin of Africa, I selected the congo river basin and I need to convert the whole Africa or just the selected area to a mask of netcdf like a basemap to use later in IDl normally is a matrix of 1 inside the river basin and ceros outside. Thansk !!!!

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You'll need to convert your shapefile to a raster format, (adding a new field and setting the value to 1), but txt or NetCDF is not necessary if you then use IDL or Matlab : a tif file (for example) would be fine. IDL reads TIFF directly and you can use imread in Matlab.

In ArcGIS : Feature to raster

In QGIS : Rasterize

Note that you can then convert to NetCDF using gdal_translate (also accessible from QGIS with Raster menu - Conversion - Translate (Convert format)) or Raster to NetCDF in ArcGIS. I would not use a txt even if the conversion is possible in ArcGIS (raster to ascii) and in QGIS, because there are many txt format and I don't know which one to use.

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  • Thank you !!! but I just need a matrix of 0 and 1 thus I can use it as basemap for a model that runs in IDL but it need to be in .nc or .txt
    – Rogert Sori Gómez
    Commented Jun 4, 2015 at 14:10
  • you can create the netcdf with gdal_translate as I mentioned in my answer.
    – radouxju
    Commented Jun 4, 2015 at 14:45
  • should I first rasterize ?
    – Rogert Sori Gómez
    Commented Jun 4, 2015 at 14:46
  • yes : first you rasterize and the you convert to netCDF.
    – radouxju
    Commented Jun 4, 2015 at 19:18

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