By David Crowther
Question:
Is it possible to generate 3D terrain mapping for anywhere in the world?
Answer:
Yes, QGIS 3 onwards has a new 3D Map View tool which allows you to visualise your mapping data in a secondary 3d Map window.
If working in the UK then you can source Digital Terrain (DTM) and Digital Surface (DSM) models from the DEFRA website.
If you are working outside of the UK, then you can utilise the Enhanced Shuttle Land Elevation data freely available from NASA. Firstly, you will need to sign up to access NASA’s Earth Science Data by creating a user account from their Earth Data website:
To then access world terrain datasets simply visit the 30-Metere SRTM Tile Downloader website - http://dwtkns.com/srtm30m/ This site provides a mapping interface to select worldwide tiles to then download 30 metre Shuttle Radar data as .HGT (height) files.
Zoom into your area of interest and select 1 or more tiles to download. In this example we will choose the tile that covers Mont Blanc.
Once downloaded you can open the Terrain data as a RASTER layer within QGIS.
Then add aerial imagery e.g. Bing Tiles as a background to provide context to the raster terrain tile.
Making the terrain layer translucent will then allow you to see through the terrain data and see the Aerial Imagery below.
To view the terrain data in 3d choose View > New 3D Map View.
And a second (3D) map window will open which can be docked below the original map window.
To configure the window to show the 3D terrain tile, choose the Configure button to activate the 3D Configuration window. In the Terrain section set the Elevation to be one of the terrain tiles previously downloaded – in this case tile N45E006.
Having chosen the 3D Configuration and pressed OK, now choose the Zoom to Extents icon to re-centre the 3D Map window over the chosen terrain tile.
Tips for Navigating the 3D Map:
- Move and Pan
- use left mouse button to drag the map
- or use the Arrow keys on the keyboard
- Zooming
- use the mouse wheel
- right mouse click and move mouse forward and backward
- Tilt Camera
- drag the mouse with middle mouse button pressed
- press shift and drag the mouse with left mouse button pressed
- press shift and use the arrow keys
For better 3D mapping/terrain viewing results you can also apply some extra settings within the Configuration window e.g.
- Increase Vertical Scale: as this will maximize the difference between low and high terrain
- Increase Skirt Height: to add vertical walls between tiles to remove any white gaps
- Increase Tile Resolution: to improve the texture of tile rendering (warning – this may have an adverse effect on model speed)