[mkgmap-dev] Creating DEM-like maps using TYP customisation

Sat Oct 3 22:29:33 BST 2009

On Sat, Oct 03, 2009 at 09:01:33PM +0800, maning sambale wrote:
> nice!  How were you able to close contours along tile borders?
> Is it possible to pre-process the contour tiles before mkgmap?

Another idea: would it be possible to create a global contour line map
from the ASTER data and distribute it?  Could the contour line map be
an overlay on a more variable map?  Would the tile borders have to match?
Could the two maps (contours and OSM-based overlay) be enabled or disabled
from the device's settings menu?

It would be useful to have a "static" contour line map, because elevation
data does not change (or is not surveyed) as often as OpenStreetMap.

Apparently, the ASTER data is not that proprietary, after all.  There is
a Norwegian mountain cycling map at http://mtbmap.org/ that acknowledges
ASTER.  According to a forum post, these are the rules:

> ASTER GDEM Policy Agreements
> 
> * I agree to redistribute the ASTER GDEM only to individuals within
> my organization or project of intended use or in response to disasters
> in support of the GEO Disaster Theme. (Required)
> * When presenting or publishing ASTER GDEM data, I agree to include
> "ASTER GDEM is a product of METI and NASA."

If the ASTER data is a set of GeoTIFF files (raster files, high resolution),
my understanding is that the contour lines (vector lines, lower resolution)
would not be "redistributing" the data but "presenting or publishing" it.
Apparently, that is how the Norwegians are interpreting it.

Best regards,

	Marko

> 
> On 9/26/09, Martin Simon <grenzdebil at gmail.com> wrote:
> > 2009/9/26 maning sambale <emmanuel.sambale at gmail.com>:
> >> Very nice.  Has anyone tried this with mkgmap?
> >>
> >> http://www.cgpsmapper.com/download/Creating%20custom%20types%20to%20represent%20elevation%20data.pdf
> >>
> >> What's needed is to simply (?) convert the contour line to polygon.
> >
> > I'm currently experimenting with this - the problem is to create
> > closed polygons per tile, similar to the sea areas mkgmap can create
> > from coastlines.
> >
> > This is what it looks like when it's working(when no open contours are
> > involved):
> >
> > http://img30.imageshack.us/img30/9595/img0854oj.jpg
> >
> > It works quite fast, even if there are many dithering layers on top of
> > each other.
> >
> > Maybe parts of the sea polygons code could be reused to extend contour
> > areas to the tile borders.
> >
> > -Martin
> > _______________________________________________
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> > mkgmap-dev at lists.mkgmap.org.uk
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> >
> 
> 
> -- 
> cheers,
> maning
> ------------------------------------------------------
> "Freedom is still the most radical idea of all" -N.Branden
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