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I'm trying to get a map of contours that are detailed to a street level that I can then import into Rhino to get an accurate landscape map of an architectural site.

Does anybody know how I can get this info that I can then export as a .dxf or in what program I can do this?

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    It highly depends where in the world you need the data (Indonesia? Zimbabwe?), what you consider "detailed to street level" and what accuracy you need. – bugmenot123 Feb 1 at 9:42
  • I'm trying to get data for Liverpool in the UK and ideally need detail that will show accurate level changes of individual streets (eg if a 20/30m stretch of street has an incline of 20 degrees I'd need a map that can show that) – Dan Jarvis Feb 1 at 12:43
  • Have you looked anywhere yet? Check for open data in Liverpool and see what is available. I imagine the best you'll find is a raster elevation model which you'd have to convert to contours yourself (lots of GIS programs to do that). Otherwise I'd have to think the Ordnance Survey is your best bet to get actual contours (though at a cost). – Mark Ireland Feb 1 at 15:48
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    OS Terran (50k) ordnancesurvey.co.uk/opendatadownload/products.html#TERR50 or find LiDAR from Environment Agency > environment.data.gov.uk/DefraDataDownload/?Mode=survey (LiDAR point cloud catalogues) – Mapperz Feb 6 at 17:12
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The steps that you should take generally is:

  1. Get elevation data - (they are rasters available in different formats and resolutions)

For a finer and more accurate map, you'll need more resolution or in other words smaller cell (pixel) size! Digital surface models(DSM) are generally more preferable for your case than digital terrain models(DTM) or digital elevation models (DEM). So look for free DSM data with a resolution of 1m which means in every sq meters you have an elevation point. Typically there is no free data for DEMs or similar with resolution (cell size) 30 meters (1 arcsec) or less. Search and you will find.

  1. Install QGIS and load the raster

It's a free and open source GIS.

  1. With the Contour tool in the toolbox select your input layer(the same raster)
  2. Fill "additional creation parameters" with "-3d" to force it 3 dimensional.
  3. Right click on the layer, Save as, and save it as DXF in a directory and you are ready to go.

Another thing worth mentioning is to keep an eye on the projection system. Most of the digital models are in WGS 84 so if you are working in a metric unit instead of angular, convert your projection at step 5.

  • Thank you, I'll give that a try this afternoon, really appreciate it – Dan Jarvis Feb 1 at 13:22
  • I disagree that DSM is preferable in this case. He probably seems to want ground elevation. Did you switch them around by mistake? – Gabriel C. Feb 6 at 17:19

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