I'm new to GIS so I apologize if this question is basic but I couldn't find my answer online.

I'm trying to reclassify a land cover raster from the National Land Cover Database. I want to reclassify into a three category raster: 1 - natural areas, 2 - agricultural areas, and 3 - developed areas.

I am going to Spatial Analyst > Reclassify and then I reclassify by unique values and enter my new values into their respective places. When I reclassify, I only get one value: 2. And it doesn't even correspond to what I've classified as 2.

What can I do to fix this? I have no clue what I'm doing wrong.

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  • Can you post a screenshot of the Reclassify Dialog with the settings you are using, and possibly of the attribute table of the raster you are reclassifying? Without more information on what your inputs are, we can't really suggest what you might be doing wrong.
    – Chris W
    Commented Dec 8, 2014 at 19:26
  • Hi Chris, thank you for your reply. I just edited my post with pictures of the attribute table and the settings I am using to reclassify. Please let me know if you see where I am going wrong.
    – Rachel
    Commented Dec 8, 2014 at 19:35
  • 1
    In your first screenshot, you have one row selected (value = 21). TBH, I don't know whether Spatial Analyst tools respect selections, but you may want to try running the tool with nothing selected. If Reclassify is respecting the selection, it is only considering pixels with value = 21, and changing them to 2.
    – phloem
    Commented Dec 8, 2014 at 19:52
  • wow! Thank you phloem. Apparently the selection was what was causing the problem the whole time... Such a small thing creating such a big frustration. Thanks again
    – Rachel
    Commented Dec 8, 2014 at 20:03
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    Wow. I can't believe I missed that. Been looking at the dialogs and screenshots for 30min. Even downloaded some NLCD data and just finished running a reclassify on it successfully, so I was going to comment I couldn't replicate the problem. I totally spaced noting that a record was actually selected. @phloem you should make that an answer.
    – Chris W
    Commented Dec 8, 2014 at 20:18

1 Answer 1


As discovered in the comments, one row (value = 21) was selected before running Reclassify. The Reclassify tool only considered the selected row, therefore only reclassified those pixels where value = 21, to the new value, 2.

Edit: it may be worth noting that there is no mention of whether Reclassify respects selections in the help page. I would be interested to know if there is documentation regarding Reclassify's or Spatial Analyst's use of selections.

  • 1
    Based on this page, I get the impression that all tools respect selection unless explicitly stated in their help that they don't. See the paragraph under the image in the Selections section.
    – Chris W
    Commented Dec 8, 2014 at 21:42

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