Through applying novel terrain rendering techniques to the UK Ordnance Survey’s Terrain 50 dataset, a new web map has been produced allowing users to explore the physical features of the landscape without the distraction of cultural features. This follows on from the Geoscience Australia case studies, improving the tile-stitching methods, applying a test colour scheme and including some additional geographical features.
The resulting prototype tileset covers some 40,000 km sq. at a resolution of 50m, including the 100km grid squares NY, NZ, SD and SE. This area contains 5 National Parks and a varied geology including Chalk Uplands, Glaciated Landscapes, Limestone Pavements, Sandstone Tablelands, Vales and Moors. Place names from the Ordnance Survey’s Vector Map District are brought in at appropriate zoom levels to orient the user and intertidal foreshore features are used to define the coastal region. The main design feature of this style of map is the addition of a vertical offset to create a 2.5D surface rendering whilst maintaining planimetric accuracy. The inclusion of the key visual cues explored in the Blue Mountains Revealed project are as described in prior posts to this blog. The image above illustrates an area of Upper Wharfdale and Littondale, Yorkshire Dales National Park, with an areal photograph below as a landscape comparator. The stepped limestone terraces are picked out well with prominent landscape features being clearly demarked.
The workflow used was similar to the previous prototypes: render and composite the raster tiles, re-project using gdalwarp for use with common web mapping libraries, use tilemill to add coastal vector data and rules for place-name inclusion and finally, render out the tileset and embed using Leaflet.js. There are still some registration errors with the addition of the foreshore feature-set from Vector Map District, and some problems with the varying of sea level height across adjacent terrain tiles. The image below illustrates an effective small-scale overview of the contained valley of Swaledale in The Yorkshire Dales National Park.
As MapBox expand their terrain rendering options (similar to the vector experiments on this blog and Whelan (2011)) and Ordnance Survey explore visualisation styles, the depiction of terrain in web-mapping platforms is being increasingly informed by a broader design agenda. The following images illustrate some areas of the UK Revealed case study, with the final image providing a link to the hosted tileset.
Whelan J. C., 2011, Web-based Vector Terrain Exploration, Proceedings of SVG Open 2011, Cambridge MA