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
_______________________________________________
gdal-dev mailing list
[email protected]
http://lists.osgeo.org/mailman/listinfo/gdal-dev
