the Relief Visualisation Toolbox

[Simon Ritchie]

The Institute of Anthropological and Spatial Studies in Slovenia has produced a piece of software called the Relief Visualisation Toolbox.  It produces all sorts of images from Lidar data.  It's free and it runs under Microsoft Windows.  (As far as I know, there is no Mac version.)

You can download the tool fom here:  https://iaps.zrc-sazu.si/en/rvt#v.  It's an executable program.  Download it, unzip it and put it somewhere where you find it later.  To run it, navigate to it using the Windows file browser and double click on the .exe file.  In my case it's rvt_1.3_Win64.exe.

That produces a window that says "IDL Virtual Machine" with a button marked Click to Continue.  Do that.

That produces a window with a box at the top marked "List of currently selected files".  Below that there is a setof tick boxes.  Each tick box produces a different style of picture.  You can experiment by producing one at a time, or use the Select All button to choose them all.

The toolbox has all sorts of options with obscure names like Anisotropic Sky-View Factor.  Once again, a search engine should help  to figure out what some of this stuff means.

To run the toolbox you need some data.  You can get some from the UK Environment Agency website as I described in earlier postings.  If your are outside the UK, you may want to use your favourite search engine to find some local Lidar data.  When you run the tool over a Lidar data file, it will produce a lot of pictures in the same folder as the file.  To avoid clutter, create a new folder, copy the data file into it, and run the tool over the copy.  Use a separate folder for each data file.

As in a previous posting, I use the data for the 1Km map square TQ1652 from the Environment Agency as an example.  If you don't have a paper map of that area you can use Google Maps to see it.  Camilla Drive, Westhumble lies at the bottom left corner of the square.  The postcode is  RH5 6AN.   Search https://maps.google.co.uk using that postcode and choose the satellite view. You can see the houses with their back gardens edged with trees and hedges.

The Analytical Hillshading option draws pictures of the landscape with shadowing, with the sun in different positions.  So for example, you can produce a picture showing what the surface will look like with the sun in the East, and then another with the sun in the South.  These views will emphasise different features.  To try this, set the Sun Azimuth Angle and the Sun Elevation Angle and tick the Select Shadowing option

Use the Add Files option to specify your data file, choose your options and press the Start button.  Wait a short time and the folder will contain a set of .tif files.  Double-click on one of them to view it.  You can see the gardens of Camilla Drive in the bottom left corner of the picture, and the A24 road, the River Mole and the railway just to the East. 

You can start to see the potential of Lidar, but if you zoom in to see more detail, the picture breaks up.  If you are lucky, there may be  some 500m resolution data available for the area you are interested in, or even 250m resolution, but that's still tantalisingly low.  Now it's becoming feasible to run your own high-resolution surveys using a drone, and that makes Lidar a lot more useful.