Sunday, October 30, 2016

The Elevated Maps of the Week

The development of WebGL and vector map tiles has led to some interesting experiments in visualizing elevation and depth data on interactive maps. For example this week we saw a couple of creative mapped visualizations of bathymetry and Lidar data. has used historical depth data of Scotland's lochs to create a series of 3d WebGL maps of four of Scotland's biggest lakes, including Loch Ness.

The depths of most of Scotland's lochs were not measured until the mid-Nineteenth Century. The first real systematic survey of the lochs was started in 1897 by the oceanographer Sir John Murray. From 1897 to 1909 Murray carried out 60,000 soundings and produced the first ever detailed charts, with depth data, of Scotland's major lochs. has digitized the bathymetry data from Murray's survey for four of Scotland's lochs and created 3d bathymetry maps. These maps allow you to explore the bathymetry contours of Loch Ness, Loch Lomond, Loch Levan and Loch Morar in 3d. also allows you to view the bathymetry contours of each loch in 2d overlaid on an aerial map.

The Cartographic and Geological Institute of Catalunya has developed a prototype terrain explorer for their 2 meter Digital Elevation Model of Catalonia. The Institute's Relief and Shadow map, created from Lidar data, uses vector map tiles to allow you to interact in real-time with a relief map of the area.

Using Relief and Shadow you can explore the DEM model of Catalonia in an interactive Leaflet & Mapzen powered map. The map includes an impressive tool which allows you to color the terrain by elevation and by the direction of the sun. This tool allows you to change the appearance of the map in real-time by painting within an interactive compass rose.

Using the color-picker tool with the interactive compass rose you can paint the terrain on the map to highlight different elevation data and different directions of light. The center of the compass rose represents lower elevations on the map and the elevations become higher as you move out towards the circumference.

Relief and Shadow is partly based on Mapzen's Sphere Map Demo. You can learn more about how Mapzen developed their 'sphere maps' tool on this Mapzen Sphere Maps blog post.

The recent addition of the extrude property in Mapbox GL means that Lidar data can also now be visualized in 3d on a Mapbox map. Over the last few weeks we have seen extrusion used in Mapbox GL to map 3d buildings. Next week on Maps Mania we will look at how this extrude property can also be used with Lidar data to create 3d visualizations of elevation data.

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