Friday, 5 August 2016

Using QOSM to provide OpenStreetMap basemap in QGIS for my slopelines project

In previous posts I have described how I have used a segmented DEM with RSGISlib, a method originally developed as part of my MSc dissertation on Martian glaciers, for visualising slopes on Earth.

I have been looking at these again, and have produced a few maps with the QOSM plugin, which dynamically loads OpenStreetMap tiles into QGIS.

These maps below were produced with the Thunderforest Outdoors rendering. The slopelines are as previously, red for convex slopes, blue for concave, with thicker lines denoting steeper slopes.

Previous versions of this had used a version of OpenStreetMap that I was preparing myself from the source data within QGIS. Using the basemap tiles I can focus on adapting the visualisation of the slope lines themselves a bit more.

Bodmin Moor

Camborne and Redruth, including Carn Brea and Portreath



A close up of Truro
For a while I thought the QGIS bug I found had recurred which meant that the arrows had disappeared. However it was something wrong in my data dependent styling, not sure how it happened. Once fixed, I show the slope direction with arrows, which is only possible up to about 1:10,000 otherwise the rendering struggles:

Indicating the downslope direction with arrows.

Delabole, showing the slate quarry.
St. Ives

Aberystwyth, Wales

Cadair Idris, Wales

A wider view of Cadair Idris, too small a scale to allow plotting the arrows.

Pen y Fan, Brecon Beacons, Wales

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