The hosted basemaps and data services in ArcGIS Online are constantly being improved as more open data becomes available. For the UK there was the recent move of the OS Open basemaps into ArcGIS Online (don’t forget to switch over if you are still using the Datahub services). Last autumn the Lidar data captured by the Environment agency of England and Natural Resources Wales were released as open data, collectively covering 70% of England and Wales. I featured the EA Lidar WMS service in a recent blog post. This amazing data resource has now been incorporated into the Esri World Elevation services, by including data from the Lidar derived DTM (bare earth). For the areas covered by the data the resolution of the elevation data comes down to 2m (orange in the coverage map below) rather than the 50m resolution (grey) of the OS Terrain 50 data used for the rest of the UK.
The data mainly covers flood plains, coastal zones and urban areas since its primary benefit is improving the quality of flood risk modelling. Anyone that has read my posts will know that I enjoy exploring maps so the first thing I did was look at some familiar places using the hillshade layer in the ArcGIS Living Atlas – the fells around Ambleside look spectacular at this resolution:
What struck me though was how many different stories from the past the landforms tell; from early settlements, through historical fortifications to the nationwide changes brought by the industrial age. The engineering feats of the canal and railway eras reshaped the land surface but it was also changed by mining, quarrying and large drainage schemes. Rather than peppering this blog post with images I’ve put together an accompanying storymap. Of course, If you have an ArcGIS Online login you can take a look at the elevation services for yourself.
But what of the data’s original purpose as input into analysis? As well as the hillshade map, the ArcGIS Living Atlas includes slope and aspect layers. The elevation service can also be used in 3D scenes. For now the ArcGIS Online analysis tools aren’t able to use of this data ,but if you have access to ArcMap you can. As a quick test I pointed the Viewshed tool (part of the 3D Analyst extension) at the Esri World Elevation service and created a viewshed from a point on one of the levels of a large quarry (just north of Merthyr Tydfil). You can see in the image that the view to the higher and the top of the hill are blocked, but with the viewpoint set back from the edge the lower levels of the quarry are also out of sight:
Where it is available, the inclusion of the Lidar data in the Esri World Elevation series gives you the ability to improve the accuracy of a viewshed – like the example shown in our windfarm storymap. If you want to make use of the data in a more systematic way there are instructions in the blog post from Esri announcing that announced the update.