Terrain shading for QGIS

A QGIS plugin for modelling natural illumination over digital terrain models.

This project is maintained by zoran-cuckovic

Terrain shading: a QGIS plugin for modelling natural illumination over digital terrain models.

Current version: 0.2

Supported QGIS version: 3.x

Repository and download: github.com/zoran-cuckovic/QGIS-terrain-shading

FIGURE SHADOWS

Installation

The algorithm for relief shading is available in the official QGIS plugin repository and can be installed as usual (In QGIS go to Plugins -> Manage and install … ). Be sure to enable experimental plugins.

If the standard installation does not work, the plugin can be downloaded for the repository (above) and installed manually: First you need to locate your QGIS plugins folder. On Windows it would be ‘C:\users\username\AppData\Roaming\QGIS\QGIS3\profiles\default\python\plugins’ (or just do a file search for ‘QGIS3’ …)

Plugin code can then be extracted in a new folder inside the plugins folder (you should name the folder TerrainShading). Take care that the code is not inside a subfolder - the folder structure should be like this:

QGIS3\profiles\default\python\plugins\
    [some QGIS plugin folders…]
    TerrainShading
        dem_shading.py
        metadata.txt
        [other files and folders…]

Finally, there is a version made as QGIS script, which can be downloaded from the script branch and installed as a QGIS script.

Manual

The pluging currently features two algorithms: shadow depth and ambient occlusion. Data input for both algorithms should be a digital elevation model (DEM) in raster format. Note that it has to be projected in a metric coordinate system.

Parameters for shadow depth algorithm

Sun direction marks the horizontal position of the Sun where 0° is on the North, 90° on the East and 270° on the West.

Sun angle marks the vertical position of the Sun.

Smooth filter is a simple 3x3 average filter which eliminates noise and sharp transitions in the output.

Remarks – For cartographic uses, the best result is achieved when varying levels of transparency according to shadow depth or length. You can download and apply QGIS style definition files from the style library in this repository.

Parameters for ambient occlusion algorithm

Radius specifies the radius of the sphere that is analysed around each data point.

Denoise will apply a 3x3 average filter, as above.

Remarks – Algorithm calculation time is directly dependant on the radius of analysis. For more information on scientific concepts behind ambient occlusion, see the post on LandscapeArchaeology.org

More information

For tutorials and in-depth discussion see LandscapeArchaeology.org/2019/qgis-shadows and LandscapeArchaeology.org/2020/ambient-occlusion.

Style library can be found in the GitHub repo.

You can signal an issue in GitHub repository.

Support & donations

If this piece of software makes you a happier cartographer, express your feelings and ko-fi