Map Algebra Calculator is a new QGIS plugin: a raster calculator that lets you choose the engine. Use PCRaster map algebra (terrain and hydrology functions such as slope, lddcreate, accuflux, streamorder and subcatchment), the GDAL raster calculator (numpy syntax), or GRASS r.mapcalc. In this video I install the plugin from the QGIS Plugin Manager and give a quick tour of the dialog. Then I use PCRaster to go from a DEM to slopes, a flow direction network (LDD), Strahler stream orders and finally subcatchments, using a multi-line script with intermediate variables. You'll also see how the value scale of each input is handled (and read automatically from PCRaster .map files). The final calculation is exported as a standalone Processing script, and the calculator is shown as Processing algorithms for the Toolbox, batch processing and the Model Designer. Chapters 0:00 Intro 0:11 Install the plugin from the Plugin Manager 0:39 The calculator dialog and its three engines 1:38 Single-line expressions 4:03 Multi-line script 5:24 Export the calculation as a Processing Script 6:31 The calculator as Processing algorithms 6:48 Use it in the Model Designer Links [Plugin in the QGIS plugin repository](https://plugins.qgis.org/plugins/mapalgebra_calculator/) [Source code, documentation and test data]( https://github.com/jvdkwast/mapalgebra-calculator) [Report issues](https://github.com/jvdkwast/mapalgebra-calculator/issues) [PCRaster Tools plugin (to install PCRaster)](https://jvdkwast.github.io/qgis-processing-pcraster) [PCRaster]( https://pcraster.geo.uu.nl) Requirements: QGIS 3.28 or later (QGIS 4 supported). The GDAL engine works in every QGIS installation. The PCRaster engine needs PCRaster in your QGIS Python environment. The GRASS engine needs the GRASS provider of QGIS Processing. #QGIS #PCRaster #GRASSGIS #GDAL #Hydrology #MapAlgebra #OpenSourceGIS