[OSM-dev] SRTM relief

[Nick Whitelegg]

On Wednesday 02 Jan 2008 22:31, Andy Allan wrote:
> On Jan 2, 2008 9:55 PM, Artem Pavlenko <artem.mapnik at googlemail.com> wrote:
> > Hello lists,
> >
> > Sometime last year I was inspired by http://www.srtm.com and I even
> > contacted developer to see if we can use SRTM derived relief maps in
> > OSM.
> > I don't remember all details but reply was somewhat ambiguous:  yes
> > OSM can use pre-rendered tiles from the site above, source code (in
> > Java ) is a bit messy, cause my crazy mate coded something ...
> > Anyway, while srtm.com tiles look good on its own, colour scheme is
> > not suitable for overlaying with OSM data IMHO. So I thought it would
> > be fairly straight forward to implement something from scratch.
> >
> > Here is what I'm thinking about - a c++ command line app, which given
> > bounding box in geographic coordinate system (WGS84) would read
> > compressed raw SRTM files and output 'nice' looking maps (tiles) in
> > specified projection (I only care about Mercator and OS NatGrid but
> > others will work as well).
> >
> > Here is more detailed feature list:
> >
> > 1. highly configurable
> > 2. all steps needed to produce final relief map included (relief,
> > blending , warping  etc)
> > 3. read raw compressed SRTM directly
> > 4. easy to add new algorithms
> > 5. using GIL from Adobe for accessing pixels and implementing algos.
> > 6. mapnik and OSM ready
> > 7. perhaps it can be used for outputting contours as well (?)
> >
> > I've coded a prototype based on excellent posting on http://
> > perrygeo.net/wordpress/?p=7 and I'm looking for a good color scheme
> > that would work for the whole planet, any pointers?
> >
> > Here is some test outputs:
> >
> > http://artem.dev.openstreetmap.org/files/relief_osgb.png
> > http://artem.dev.openstreetmap.org/files/srtm_relief.png
> >
> > (red pixels are voids and I'm yet to fill them, did someone mentioned
> > some good algorithms a few months ago?)
> >
> > The kind of reliefs I think might work well for OSM are gmap terrain
> > or perhaps Yahoo style.
> > Any ideas or comments? Cartographers?
>
> WANT.
>
> :-)
>
> I'd like on the cycle map to show relief at low zoom, and something
> approaching the "Color ramps" from that linked blog post at high zoom
> (relief is generally impossible to make out when you get zoomed in too
> far). The thing I've been wanting and getting nowhere towards is both
> of those concepts with contours too (for a bit of precision), so if
> this tool of yours can do contours, relief and colour ramps then I
> could fiddle with the colours till the cows come home. Which is all I
> want to do really, since I've pretty much sucked at getting contours
> done myself*
>
> Cheers,
> Andy

Hello Andy,

There is the srtm2shp utility available in SVN which outputs a shapefile of 
contours, it outputs in Mercator - is that any good? It doesn't deal with 
SRTM voids yet.

Nick