[gdal-dev] Auto-clip collar for DRGs/DOQQs/BSBs

[Klokan Petr Přidal]

Hello!

I wonder if there is a script for image analyze and automatic clipping
for the freely available USGS DRGs and NOAA BSBs map sheets...

I guess it is quite often requested functionality and I am sure there
are some implementations for that already available, maybe even
open-source.

Do you know about such script?
Were there some diploma/PhD thesis about this problem (directly
related to DRGs and BSB maps)?
Or are there some already pre-calculated masks/bounding boxes or
polygons for the DRGs and BSBs popular sheets on the net?
What kind of image analyze should be used for this processing
according your idea?

I can imagine that to write an universal function would be hard, but
something what will be able to auto-clip for example NOAA BSBs should
not be as hard, as those maps are using similar palette and are well
aligned to the raster grid as (I think) they were rasterized from the
vector data - not scanned.

I thought about some palette shifts and then detection of the edges,
but I guess it could be done a better way - and maybe somebody already
did it...

It would be nice to present some stitched maps and remove the borders
in the examples of rendering capabilities of GDAL2Tiles at
http://examples.maptiler.org/.

Best reagards

Klokan Petr Pridal

P.S.
I know GlobalMapper software has an implementation of this
functionality, but how to do the same with GDAL to be able to automate
the process?