[Openstreetmap] Map of Oslo and Norway? (Was: Legal viability of using Landsat and SRTM data as basemaps)
nick at hogweed.org
Thu Apr 21 23:14:00 BST 2005
On Wednesday 20 Apr 2005 22:49, Petter Reinholdtsen wrote:
> [Nick Whitelegg]
> > The SRTM data is, I believe, public domain data. For a demo visit
> > the Freemap site: contours for the whole of the UK below 55N are
> > present. You can also download the source code (PHP) of the site,
> > including the contour generation routine, at
> > http://www.free-map.org.uk/downloads.php. The code is under LGPL.
> How much work is for you to add more areas to your installation? I
> would like to have something similar for Norway, but am not sure if I
> will find the time to duplicate your installation myself.
Not too much - the only thing is, Freemap stores everything in UK grid
projection rather than lat/long so it would involve some conversion.
> > The source code tarball is a month or two out of date (includes
> > contours but no height shading which is on the current version of
> > the website) but I hope to upload a more recent source code tarball
> > very soon.
> How much disk space do you use to store the map over England? Is
> there much processing up front before the map is usable? I noticed
> some comments about processing the elevation data.
It's about 120MB so far, for everything below 55N. The data is in a binary
format of heights sampled every 90m or so, so some coding is necessary for
the data to be displayed. I figured that generating the contours from the
data would be more flexible and require less storage space (if slower) than
pre-generating them as static images (lack of scalability of which would be a
If enough people would like a SRTM contour generation routine in a language
other than the present PHP, I could work on a conversion.
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