[gdal-dev] Heuristics to classify raster data ?

[Dmitriy Baryshnikov]

Hi Even,

most of all depends what kind of imagery and maps you wish to classify. 
If the maps are classical scanned paper maps, and you want fast 
algorithm - the crosses of meter or degree grid can be the good pattern.
But if we have areal images this will not work, as such images have 
crosses too. But satellites - not. May be some frame of maps can be good 
pattern.

If you have some fragment of maps and images, I think some content 
analysis needed:
- clustering, i.e. http://en.wikipedia.org/wiki/K-means_clustering
-Neural network with learning
-Support vector machine i.e. http://svmlight.joachims.org/ and 
http://en.wikipedia.org/wiki/Support_vector_machine

Also some hash comparison can be used (rather fast)
- perceptual hash compare  i.e. http://www.phash.org/

In all cases input images should be resized to some small sizes and may 
be grayscaled or binarized before analysis.

Best regards,
     Dmitry

06.03.2014 23:19, Even Rouault ?????:
> Hi,
>
> I'd be interested in an algorithm to automate the classification of raster data
> between maps (let's say rendering of OpenStreetMap data, or other digital
> maps) one one side and aerial/satellite imagery on the other side, without
> looking at metadata (bare geotiff typically). This is to help in automating
> bulk of import of data from a media and establishing a first level of
> classification.
>
> Has anyone already done that and has code and/or advice to share, or know a
> software project that would do that ?
>
> Some ideas that came to my mind :
> - maps have typically a much more reduce number of colors than imagery, but
> you may have imagery that has already been transformed to 256 colors to reduce
> storage space.
> - maps have generally a majority color (e.g. white, green), but not in all
> zones (urban zones will have more features)
> - maps have higher spatial frequency (lines, text) whereas imagery will be
> more continuous : use of gradient, and compute statistics on it ?
>
> Even
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/gdal-dev/attachments/20140307/f5350d98/attachment.html>