[Talk-GB] OS OpenData contours
Nick.Whitelegg at solent.ac.uk
Mon Feb 7 12:45:53 GMT 2011
>> Am interested in using the OS OpenData contour set for an
>> augmented reality app for walkers (extension of the OpenTrailView
>> idea). What I have in mind is to load them into a database
>> and implement a lookup facility where the elevation at a
>> particular lat/lon can be obtained by querying the dataset.
>> I believe the OS contours are rather higher precision than
>> SRTM, hence my interest in them, but to potentially save
>> effort, has anyone done something like this already?
>I believe you've asked me about this before, and I have code to parse
>the gridded version of this data and to create binary files from it,
>similar to the ".hgt" files that SRTM is distributed in. The total
>size is about 60 MB in about 13,000 gzipped files, one per 5km square,
>with a 50m horizontal resolution. Trivial interpolation within the
>grid seems to work pretty well compared to OS spot heights e.g. within
>5m on summits, which is much better than I get using SRTM. I also have
>a version that is downsampled to a 200m grid which is of course much
>smaller. Lookups are quite straightforward once you have converted
>your lat/lon to eastings and northings.
>You are welcome to take a copy of this data, if you would like it.
Yes, could be useful, thanks. Sorry - what I thought I asked about last time was about VectorMap District data. No great urgency - just thought I'd raise it now as the OpenDEM post on the talk list reminded me about it.
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