[gdal-dev] Contour Line Thinning

[Stephen Woodbridge]

Hi all,

I'm contouring bathemetry data using gdal_contour and it works really 
great. The problem I have is that when depth falls off rapidly like at 
the continental shelf or into a canyon, I get too many contour lines 
that all bunch up. If I change the contour step size to fix this, then 
the flatter areas don't get enough lines.

I wonder if anyone has any ideas on someway to thin these lines or some 
way to do adaptive contouring based on maybe something like scanning the 
image first to build a masks that represent these rapid changes in depth 
and then change the contour levels in these masked areas.

I currently contour into a postgis database, the render them using 
mapserver into a tile cache since they are static once they are computed.

I would be interested in any ideas you might have on how to tackle this 
problem.

-Steve W