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I have a raster with the extension .tif. It's a subset of 87x87 pixel with values from some 6,66 to -4,27. If I right click on it there is no Attribute Table available. However, I can change the Symbology to Unique, Streched, Classified or Discrete Color and also classify manually, everything just fine. However, I need this attribute table, as I want to calculate the statistics of the values (not only the simple like mean and min, i got those, but a bit more advanced). The ArcGIS help site ('Build Raster Attribute Table (Data Management)') mentions, that: 'It is not possible to build a raster attribute table for a raster dataset that has a pixel type of floating point or double precision.' My values, however, ARE 32bit floating point. Does any of you have a clue what I can do?

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The solution to this problem is to multiple your grid by 100 to move the digits to the left of the decimal point. I suggest 100 as your example are to 2 decimal places, if it were 3 then you multiple by 1000. After the multiplication you may need to run your dataset through the INT tool to make sure it is converted to an integer grid.

Do your analysis then divide by 100.

  • +1 but I think a tif to grid conversion step needs to be added at the beginning of this procedure. – PolyGeo Nov 20 '13 at 19:43
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    @PolyGeo no conversion required. ArcGIS 10+ treats tifs as any other type of raster. It uses GDAL 'under the hood' now for raster reading so you can even drop GDAL VRTs into the ArcMap TOC. – user2856 Nov 21 '13 at 8:35
  • Maybe I don't get the obvious, but isn't PolyGeo right? I have a tif which has no attribute table, so before I can multiply the values by e.g. 100 I need at least some kind of table. Thanks for editing and answering. – Tatue Nov 23 '13 at 17:35
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    @Tatue, no you don't need a table before you can do any arithmetic (i.e multiply by 100) on a raster as you would use the raster calculator to perform the arithmetic, not the field calculator. – user2856 Dec 16 '13 at 22:10

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