7.8.3. Example 3: Computing intersections between a DEM and planes
GIS is very useful for applications in natural sciences and a variety of tools are provided, e.g. for visibility analysis or to delimit watersheds, calculate flow paths, or even simulate natural hazards. This example demonstrates a very specific function, based on the qgSurf plugin for QGIS:
- Load and activate the plugin qgSurf (see section 7.1.3.).
- Go to Plugins.
- Select qgSurf.
- Select the DEM ASTER30_dem_CH1903 and choose source point for the plane (e.g. around Fribourg 578000/183000/627).
- Play around with the values for orientation and inclination of the plane and calculate the intersections (Fig. 108).
- Save the output as point or line shapefile.
To analyse spatially related processes in more detail or for modelling,
functions within GRASS GIS (http://grass.osgeo.org, Neteler and Mitasova, 2008) or SAGA (http://www.saga-gis.org) can be useful. To access these, GRASS
and/or SAGA have to be installed on your computer and within QGIS the SEXTANTE Toolbox plugin (http://plugins.qgis.org/plugins/sextante) needs to be installed and configured
correctly (see QGIS Development Team, 2013). If you work with R, the plugin Spatial Data Analysis for Point Pattern
(SDA4PP) might also be a good option (see section 7.1.3.).
Fig. 108. Spatial analysis computing the intersection between a DEM and an inclined plane with the QGIS plugin qgSurf.