Is it possible to create a raster with a constant value with multiple attributes? Such as:

rowid  value  count  Name
1      630    36000  Forest
2      630    75000  Anthro
3      630    2600   River
4      630    5500   Harvested

The above table would create a constant elevation but have different attributes for each cell. I have tried a reclass but it deletes the existing attributes leaving only one row.

  • Could you please explain the relationship between "elevation" and "rowid, value, count, Name"? Also, how exactly should the attributes be assigned? Randomly? If not, where do they come from? – whuber Jul 11 '12 at 22:11
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    @whuber the elevation is from the value field, the attributes are assigned from polygon overlay or from an existing raster such as land-cover class. – user6784 Jul 11 '12 at 22:30
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    OK: so what you mean by "constant elevation" is not that the raster represents a constant elevation, but rather that (1) it needs to have an attribute table and (2) each record corresponds to a unique combination of elevation and land cover class. Is that right? – whuber Jul 11 '12 at 22:32
  • @whuber the elevation (value) field will always be constant in the above case 630m. Pixels would then be grouped by similar attributes, such as differing land cover class. I have added a few more cover classes under "Name" in the above example. – user6784 Jul 12 '12 at 15:32
  • I'm sorry; I'm even more confused now. If the elevation is constant throughout the raster, then what's the point of including it as an attribute? Why not just rasterize the polygons and be done with it? Also, I am wondering how you mean "grouped": does that imply a spatial grouping or are you just referring to the individual records in the attribute table (each of which describes all cells having a particular tuple of attributes, regardless of those cell locations)? – whuber Jul 12 '12 at 15:35

This grid looks like the result of a Combine operation. It overlays two co-registered categorical ("integer") grids, producing a table of all unique combinations of categories appearing among the cells.

To apply that here, create a constant grid equal to the elevation. Make sure it is categorical (such as by applying Int). Combine this with the other (e.g., land cover) raster.

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  • Thanks @whuber I looked at this method and I does not look like it will preserve the elevation value (in the example 630) for each cell. I'm not sure if what I am asking is even possible with the data structure inherent to raster files. – user6784 Jul 12 '12 at 17:28
  • Have you tried it? It definitely works as described. – whuber Jul 12 '12 at 18:28
  • @ whuber - I have tried the method and it produces a new raster with attributes populated with the value field from each of the two combined rasters (elevation and cover-class). Is it possible now to use this as a DEM specifying that the elevation attribute be used as the z value? Its my understanding that the elevation must be in the value field for this to still work as a DEM. – user6784 Jul 12 '12 at 19:40
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    Well, this is why I'm so mystified by your question. Even when a raster has multiple fields, most operations must reference a single field. (They internally convert that into a raster with just one attribute.) I can't think of any ArcGIS operations that operate directly on multiply-attributed rasters. – whuber Jul 12 '12 at 22:18
  • - for visualization purposes in ArcScene this could be used. – user6784 Jul 13 '12 at 19:56

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