[GIS] Importing raster adf files with the additional files

attribute-tableesri-grid-formatqgis

I am trying to import a vegetation data raster in Esri GRID format from the USDA into QGIS. One file ("w0001.adf") can be added using "add raster", but the attribute table and other info register as error or errors. Using the "ArcInfo/Binary directory" does not work either.

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The .adf file is one component of an Esri GRID 'file', much like the .shp is one component of a shapefile. The other component files generally aren't or don't need to be accessed individually. If you can load that w0001.adf file and see the raster image, I suspect you're seeing all the data. I opened/added the file in Arc with no issue. In looking at the attribute table for the raster there, there's just a second, coded, numeric value field - you won't see the text strings describing what those coded values are (that info is listed in the metadata).

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[GIS] Can QGIS handle *.adf raster attribute data

Qgis uses gdal to access .adf rasters, Arcinfo Binary Grids (note: .adf files are also used for Arcinfo vectors). Reading the reverse engineered Arc/Info Binary Grid Format description page one sees

vat.adf: This relates to the value attribute table. This is the table corresponding integer raster values with a set of attributes. I presume it is really just a pointer into info in a manner similar to the pat.adf file in a vector coverage, but I haven't investigated yet.

So, no Qgis probably can't read Arcinfo raster attributes. That document was written a long time ago though, so perhaps things have changed.

I don't have access to a vat-enabled raster right now so can't test, but I surmise the structure outlined in the Raster dataset attribute tables Arcgis help is likely quite similar to the vat.adf structure, for those wishing to plug the hole in the format description and perhaps extend the gdal aigrid format driver.

GDAL_translate – Converting ESRI GRID to GeoTIFF in Batch

You could script it in python with os.walk, fnmatch and subprocess.Popen. Alternatively, here's a batch file to do the same thing.

The key is that gdal can use either the grid name (directory) or grid name\hdr.adf to open the grid. To tell the difference between grid and vector coverage directories, the for loop searches for w*.adf as they are only found in grids.

@echo off
SET startpath=%1
FOR /R %startpath% %%f IN (w*1.adf) do (call :translate "%%f")
pause
GOTO :eof

:translate
  SET var=%~dp1
  ECHO Translating %var%hdr.adf to %var:~0,-1%.tif
  gdal_translate %var%hdr.adf %var:~0,-1%.tif

Edit: just tested and found that gdal can also read the grid when passed the w001001.adf file as well as the directory name and the hdr.adf file.

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[GIS] Can QGIS handle *.adf raster attribute data

GDAL_translate – Converting ESRI GRID to GeoTIFF in Batch

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