[GRASS-user] r.in.gdal for importing categorical ArcGIS binary rasters

[Markus Metz]

On Fri, Feb 21, 2014 at 5:39 PM, Vaclav Petras <wenzeslaus at gmail.com> wrote:
> Unfortunately, I have data where GDAL does not identify the columns.

Does GDAL find a raster attribute table?

> One is
> the only string there, and the other three are the red, green, blue (in the
> range 0-1).

... which would need to be transformed to the range 0,255.

Here it seems easier to edit the attribute table outside GRASS, then
use r.category and r.colors.

> For me it is clear what column I would like to transform to
> label and to color rules but I'm not sure if GDAL has even a chance to
> determine it somehow. So, some options to set this would be great.
>
> I can share the data, they are from a public source.

I would be interested.

Markus M

>
> But anyway, connection to color tables and labels is great, colors and
> labels solves at least significant part of the cases where raster attribute
> tables are used.
>
> Vaclav
>
>
> On Fri, Feb 21, 2014 at 11:26 AM, Moritz Lennert
> <mlennert at club.worldonline.be> wrote:
>>
>> On 21/02/14 17:12, Markus Metz wrote:
>>>
>>> On Fri, Feb 21, 2014 at 2:00 PM, Moritz Lennert
>>> <mlennert at club.worldonline.be> wrote:
>>>>
>>>> On 21/02/14 11:30, Markus Metz wrote:
>>>>>
>>>>>
>>>>> On Fri, Feb 21, 2014 at 9:35 AM, Moritz Lennert
>>>>> <mlennert at club.worldonline.be> wrote:
>>>>>>
>>>>>>
>>>>>> On 20/02/14 22:14, Markus Metz wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> I would not replace a working gdal version with a probably not
>>>>>>> working
>>>>>>> gdal version. Your gdalinfo reported a raster attribute table, not
>>>>>>> mine. You could double-check again if your gdalinfo still finds a
>>>>>>> raster attribute table, then import with r.in.gdal.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Out of curiosity: if a table contains several columns which one(s)
>>>>>> is/are
>>>>>> imported and in what form do they appear in GRASS (I don't have a file
>>>>>> here
>>>>>> to test myself) ?
>>>>>
>>>>>
>>>>>
>>>>> Each column has a dedicated usage. For "name" usage, the column is
>>>>> treated as category labels. For any of the color usages, the column is
>>>>> treated as corresponding red, green, or blue color. See also the gdal
>>>>> documentation [0]. Currently, r.out.gdal exports category labels or
>>>>> color rules to a raster attribute table with the new -t flag, and
>>>>> r.in.gdal automatically imports any information it finds.
>>>>>
>>>>> Markus M
>>>>>
>>>>> [0] http://www.gdal.org/gdal_8h.html#a27bf786b965d5227da1acc2a4cab69a1
>>>>
>>>>
>>>>
>>>> So, IIUC you get the GFU_Name and the color information, but if the
>>>> table
>>>> contains several fields (which I guess will be of type GFU_Generic)
>>>> these
>>>> are ignored ?
>>>
>>>
>>> GFU_Generic usage is ignored because it is unknown what this could be
>>> good for.
>>
>>
>> VAT tables allow as many fields as the user wants, not only a class name.
>> But I don't know (and can't tell from ESRI's documentation) whether these
>> additional fields will all be considered GFU_Names or GFU_Generics) and as I
>> don't have relevant data here (and data that colleagues created for me
>> causes an error with gdal...) I can't test this at this stage.
>>
>> My question was: if a raster has several fields as in the attribute table,
>> would it be possible to chose the field to use as labels in GRASS ?
>>
>> Moritz
>>
>>
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>
>