[gdal-dev] GDAL Raster Attribute Tables.

[Frank Warmerdam]

Peter,

Actually, I should have added that I think a following stage should be for
you to prepare a formal detailed RFC proposal for voting on by the PSC
rather than just throwing a patch at us since this is an API change.

Best regards,
Frank


On Tue, Apr 23, 2013 at 3:16 PM, Frank Warmerdam <warmerdam at pobox.com>wrote:

>
>
>
> On Tue, Apr 23, 2013 at 1:57 PM, Peter Bunting <petebunting at mac.com>wrote:
>
>> Hi All,
>>
>> We were wondering if there is any interest in the GDAL community for
>> improving the Raster Attribute Implementation? Within our group of
>> collaborators we have been representing image segmentations as clump files
>> often large attribute tables containing millions of rows and numerous
>> columns of data used for classification. We are finding the current
>> approach that reads a single value at a time with the whole attribute table
>> in memory to be quite poor performance wise and resource (i.e., memory)
>> hungry.
>>
>
> Peter,
>
> You do seem to be pushing raster attribute tables well beyond the expected
> use cases.
>
>
>>
>> We would like to propose a new implementation that allows reading and
>> writing of whole chunks of a single column within the attribute table more
>> like RasterIO.
>>
>
>> If we were to create a patch, would the GDAL community be receptive to
>> this? We were thinking this would be incorporated within the interface
>> changes in GDAL 2.0.
>>
>
> I would be receptive to additional read (and perhaps write) methods for
> chunks of the attribute table at a time if it can be done with a minimum of
> distruption of the existing api.
>
>
>> It has been muted that OGR might be merged into GDAL in version 2.0 if
>> this were to occurred how would attribute tables be dealt with and are the
>> changes we proposing something that needs to be considered in that wider
>> context also?
>>
>
> I had not been contemplating treating raster attribute tables as OGR
> layers.
>
> I must confess that I'm still not certain that pushing raster attribute
> tables to be very large is a good idea.
>
> Best regards,
>
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | Geospatial Software Developer
>



-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam,
warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Software Developer
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