High points in an area map generator

Script for generating a map of the highest points in each area given a set of polygons and spot heights over the same region. Tested on the Ordnance Survey OpenData for the counties of Great Britain.

Example output:

Contains OS data © Crown copyright and database right 2022. This information is licensed under the Open Government License v3.0.

Tools used:

• GeoTools - Java Geospatial library

References:

• GeoTools tutorials
• GeoTools javadocs
• Ordnance Survey Open Data Products
• Ian's random blog - GeoTools Contouring 24/12/2020
• Results validated against: Walking Englishman - County tops of England

Known Issues:

• Some of the highest points in counties are missed since we are using the spot heights provided which don't cover all locations.
  • Next steps: either use the contour data or grid coverage of heights to find the missing high points.
• Carnarvonshire has multiple high points on each of its islands.
  • Next steps: handle disjoint counties correctly using a unique county identifier to record their max height point.
• Some labels are not displayed on the map if they are too close to other high points. Generally it is possible to zoom in, and they will become visible.

How to set up the Ordnance Survey Dataset for Great Britain?

1. Download county boundaries:
   • https://osdatahub.os.uk/downloads/open/BoundaryLine - Download the ESRI® Shapefile option.
   • Extract the zip file and save the directory named Supplementary_Historical in the data directory. It contains a shape file containing the boundaries of the counties.
2. Download height data:
   • https://osdatahub.os.uk/downloads/open/Terrain50 - Download the ESRI® Shapefile (contours) option.
   • Extract the zip file and save the directory named terr_50_cesh_gb in the data directory. It contains shape files containing the spot heights and contours recorded by Ordnance Survey.
   • Extract the nested zip directories. On windows you can run the following bat script from the terr_50_cesh_gb directory, and it will recursively use 7-Zip to extract the nested directories.

FOR /D /r %%F in ("*") DO (
    pushd %CD%
    cd %%F
        FOR %%X in (*.rar *.zip) DO (
            "C:\Program Files\7-zip\7z.exe" x "%%X" -o*
		   del "%%X"
        )
    popd
)