GRASS GIS command line tools can be used in an interactive session or batch jobs. In Puhti, GRASS GIS is included in QGIS module. GRASS is available in Puhti with following versions: Please read on in 02_grass-gis_ecad_analysis.md.GRASS (Geographic Resources Analysis Support System) is a free Geographic Information System (GIS) software used for geospatial data management and analysis, image processing, graphics/maps production, spatial modeling, and visualization. Select GRASS GIS database directory: /home/youruser/grassdata. The following screen will come up (with slighly different entries but see below): Start it from the menu, or from command line: # in a terminal, enter supervised classification and regression of GRASS rasters using the python scikit-learn package with r.learn.ml.Vector map metadata info, attribute selection, univariate statistics, vector to raster conversion: v.info, v.db.select, v.univar, v.to.rast.Raster map metadata info, map calculator, univariate statistics, raster stack aggregation: r.info, r.mapcalc, r.univar, r.series.Import raster, vector data, import and project on the fly:.Working with computational region: g.region.General commands to start GRASS GIS, set region, list data: grass78.Here is a list of some GRASS GIS modules we will be using in this exercise and the links to their manuals: Further data have already been imported in a similar way into the GRASS GIS mapset ecad17 in the location ecad17_ll in order to not spend too much time here on importing. When processing spatial data in GRASS GIS, the first step is to import the datasets of interest into GRASS GIS (they can even just be registered to avoid data duplication at the expense of sometimes lower data quality).įig: Geodata formats versus GRASS GIS databaseĪs an example, we will further on import the elevation data (above extracted into folder geodata, file "ecad_v17/elev_v17.tif") required for the exercise. inside.įig: GRASS GIS Database example Workflow overview It carries metadata including projection and can be used to store all base geodata like elevation model etc. One default mapset folder, auto-created by GRASS GIS must be there: PERMANENT. mapset folders: used to organize data with the locations.project folders (commonly names " locations"): subfolders in the grassdata folder which have to be generated by GRASS GIS itself.GRASS GIS is offering multi-user support. Optionally, it can also be placed on a shared network device. If you don't have this folder yet just create it in your HOME directory. grassdata folder (it may have any name): used to store all GRASS GIS data.Vector maps are always processed entirely.įig: Example for a computational region Data management Vector maps: Note that this concept does not apply to vector maps. To work on the full map, the computational region is simply set to the raster map. Using the g.region command the active area. Why this? Because raster maps can be large and one may want to first explore a subset of the map. Raster maps: While the GRASS GIS import tools always import the entire map data, any computation and analysis in the raster model adhere to the so-called computational region which is nothing else that the currently active bounding box and a defined spatial region. The current region or computational region is the actual setting of the region boundaries and the actual raster resolution (see GRASS GIS Wiki). Newly produced maps like analytical results can then be exported to common GIS formats or, in case of vector data, to e.g. Espectially for raster maps it is also possible to just link data into the GRASS database (this avoids the almost double disk space consumption). ) need to be imported into the GRASS GIS database (which is simply a folder structure with data inside). Hence, all external data files (GeoTIFF, SHAPE, GeoPackage. The rationale is that all of the common GIS formats have some limitations (well, the original GRASS GIS developers just missed the chance in the 1990s to make it an official format through the OGC.). aerial imagery and satellite data) and vector data are stored in GRASS internal formats. Google Scholar: List of publications related to GRASS GIS.Presentation - GRASS GIS 7 capabilities: a graphical overview.A lot of different topics: Just browse the keyword index of the manual.Oh, and it is free and open source software. GRASS GIS is, in general, not much different from other GIS systems while it offers a series of advantages when processing massive datasets, perform geospatial analytics and repair vector topology.
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