Lines

Tanaka contours for The Long Mynd, Shropshire

Inspiration and instructions from: Landscape Archaeology

Tanaka contours for The Long Mynd, Shropshire.

Data

• SRTM data downloaded from EarthExplorer.
• Shropshire, Telford and Wrekin boundary (combined) from ONS Boundary Data (Contains public sector information licensed under the Open Government Licence v3.0.)

Tools used

• QGIS.
  • QGIS Hub plugin

What did I learn?

• Using QGIS Hub plugin - where to find the style!
• Was somehow expecting style to do the full colours, but then realised need to style the SRTM data underneath the contours. The style only provides the shading in greyscale for the contours.

What would I do differently or want to find out?

• Tried some blending modes on the styled contours. Could be good to make a “poster” showing the differences. Very effective!

Process (more detail about how I made the map)

Attempted first in R, but struggled to load data. Need to do more in R before I start doing this sort of thing! Was very easy in QGIS once I worked out I needed to style the SRTM layer.

Preparing data

• Merged SRTM layers, reprojected to British National Grid (EPSG:27700), then used Shropshire boundary to mask the raster.

Workflow

• Toolbox - GDAL > Raster extraction > Contour.
  • Used 50 m contours.
• Used QGIS Hub plugin to download style for Tanaka Contours.
• Applied to 50m contours.
• Styled SRTM raster layer with viridis colour ramp.
  • Set Interpolation to Discrete.
  • In this case need 11 classes.
  • Set classes to 50m intervals to match contours.
• Setup layout and exported to image.