[mkgmap-dev] [PATCH] Creating contour lines from DEM data

Fri Jul 3 21:13:00 BST 2009

Dear all,

the attached java classes together with the patch enables mkgmap to 
create contour lines directly from digital elevation model (DEM) data. 
This may be useful for those who don't want to ceate contour lines with 
other tools and store them in huge(!) files.

It introduces the following new options:
--contours   If set, create contours.
--dem-type  Valid values are CGIAR (CGIAR geotiff), ASTER (ASTER 
geotiff) or SRTM (.hgt files). Default is CGIAR.
--dem-path  Path to the DEM data files. The default is type-dependant.
--dem-increment Verical distance between the contour lines (default is 10m).

The algorithm used is a modified version of that described in "An 
Adaptive Grid Contouring Algorithm" by Downing and Zoraster (see 
http://mapcontext.com/autocarto/proceedings/auto-carto-5/pdf/an-adaptive-grid-contouring-algorithm.pdf) 
and uses bicubic interpolation of the DEM.

Please feel free to send me improvements, bug reports etc.

Best wishes
Christian

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