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I am pretty new to GIS, so forgive me if this is a stupid question. I downloaded a bunch of land cover files from USGS seamless warehouse of Florida. Every time I try to 1) view the .adf file (which I am assuming is the raster data image) in arcCatalog or 2) add the .adf file in arcMap the program crashes. Any reason for this? I am running the trial version of ArcMap 10 on my home PC in order to avoid using the slow ones at my universities lab, so I figured maybe I am missing some kind of extension or something. I am not really sure, I do not have much experience working with raster data so far.

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Tell more how it crashes. Maybe it doesn't crash but just 'works according to specification'? – r.pankevicius Mar 3 '12 at 7:06
up vote 6 down vote accepted

An ESRI grid is actually a group of files with the extension '.adf', all stored in a folder with the grid name (limited to 13 characters). The folder should contain files like:

  • dblbnd.adf (boundary file with min, max of the grid)
  • hdr.adf (header file containing cell resolution etc)
  • prj.adf (projection - sometimes missing)
  • sta.adf (statistics - sometimes missing)
  • vat.adf (value attribute tale)
  • w001001.adf (the value of each cell by tile)
  • w001001x.adf (the corresponding block index for each tile)

When you see this folder in ArcMap or ArcCatalog it should look like a single raster file without an extension and normally you can't drill down into the grid file folder from within Arc. You must not mess with this folder or delete the 'info' subfolder that will also appear in your directory.

I don't know why Arc is crashing but I wouldn't expect to load a single '.adf' file as such in ArcGIS. So, I wonder if you have incomplete grids or perhaps have muddled your grid folders?

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Thanks for the input. Very helpful. I consulted the ESRI forums as well and was told something similar. The crashing was occurring because apparently grid files do not "like" to be deep in a folder path. So when I put the .adf file folder right at the root of my c:\ drive they loaded up in ArcMap with no problem. – Chaz Mar 3 '12 at 20:34
Ah! Yes - that is true. ESRI has a 255 character limit on the grid file path + name. Sorry I didn't think to mention that as I got mesmerized by the '.adf' issue. At least you are sorted now! – MappaGnosis Mar 4 '12 at 20:28

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