[OSM-dev] [Talk-GB] Viability of huge shapefile of LandForm Panorama contours in Mapnik?

Keith Sharp kms at passback.co.uk
Sun Mar 6 14:21:00 GMT 2011


I'll add my name to the list of people who had this on their todo list :-)

My approach was going to be importing both the LandForm Panorama and Vectormap District files into Postgres and then using either Mapnik or Geoserver to provide tiles for an OpenLayers sloppy map.

I didn't make much progress beyond an initial import of the Strategi shapefiles into Postgres, details of where I got to are on the blog I started:

	http://usingopendata.wordpress.com/

I had got Geoserver running and connected to the database, but only had it rendering the coastline.

Now that I've finished relocating back to the UK I should have more time to work on this again.

Keith.

On 06-Mar-2011, at 11:47 AM, Graham Jones wrote:

> Nick,
> This has been on my list of things to do for a while too, but like many of my project ideas, it didn't get that far!
> I do not have any experience of the OS contour files - I coudn't work out how to convert the dxf's into something more useable by mapnik (I quite fancied getting them into postgresql like I did with srtm data).  I think the OS height data comes as a DEM as well as a DXF so it should be possible to process it like SRTM?
> 
> I did have a similar issue with rendering the Vector Map District data though, which comes as lots of shapefiles.  I tried it two different ways:
> 	• Render each shapefile individually using mapnik, by writing a python script to add a different mapnik layer for each shapefile - this worked fine for a single grid square (e.g. NZ), but it keeled over when I tried to do it for the whole UK - ran out of memory I think.
> 	• Pull the shapefiles into a postgresql database and render it just like OSM data - lines and points worked fine, but I had trouble with polygons - lots of errors about invalid geometry.  This was a shame because the big thing I like about VMD is the area data.   It looked as though the problem was areas intersecting themselves, but I never worked out how to fix it - I suspect that it may be rounding errors and I should have used the shp2pgsql option to just use integers, but I think I must have got bored before I tried re-importing the entire database again.
> I made some notes as I went along, which you should be able to see here.  The scripts I wrote and mapnik stylesheets are in a public archive, which should be referenced in my notes.
> 
> I suspect that you will have a similar problem with the contour shapefiles as I had with the VMD ones, so I would be inclined to go for the database option, or at least treat that as a contingency plan.
> 
> I would like to see this idea working, so if you would like any help, please let me know.
> 
> Regards
> 
> 
> Graham.
> 
> On 6 March 2011 09:11, Nick Whitelegg <Nick.Whitelegg at solent.ac.uk> wrote:
> Hi,
> 
> Sometime, perhaps over Easter, I'd like to do something I've been meaning to do for a while, and that is create "pseudo-Landranger" maps by combining OS Vector Map District, contours from OS Landform Panorama, and OSM footpaths. 
> 
> However, to do this I need to transform the contour data from DXF into something more usable, e.g. shapefile. Apparently gdal can now do this.
> What I'm a little concerned about, though, is the viability of creating one huge shapefile containing all the contours for the UK, which would be necessary to prevent the Mapnik XML file getting messy and having huge numbers of small shapefile layers. As an alternative I could create separate shapefiles for say, Wales, S England, N England and Scotland.
> Is this likely to be feasible.
> 
> Thanks,
> Nick
> 
> _______________________________________________
> Talk-GB mailing list
> Talk-GB at openstreetmap.org
> http://lists.openstreetmap.org/listinfo/talk-gb
> 
> 
> 
> 
> -- 
> Graham Jones
> Hartlepool, UK.
> 
> _______________________________________________
> Talk-GB mailing list
> Talk-GB at openstreetmap.org
> http://lists.openstreetmap.org/listinfo/talk-gb




More information about the dev mailing list