# Introduction to GRASS GIS
0. Course Organisation 1. Database model 2. Commands 3. User interface 4. GRASS GIS exercise
## Course organisation ### Assignment 2 is due this Friday. - Indicate which repository should be graded in this [issue](https://courses.gistools.geog.uni-heidelberg.de/fossgis/home/-/issues/13)
### Group project - Post your preferred groups of 2 for the group project in this [issue](https://courses.gistools.geog.uni-heidelberg.de/fossgis/home/-/issues/12)
### Assignment 3 is now online - https://courses.gistools.geog.uni-heidelberg.de/fossgis/fossgis_assignment_03 - Deadline: **Friday, 29.11.** - Post your preferred groups of 2 for assignment 3 in this issue by **Friday, 15.11.**: https://courses.gistools.geog.uni-heidelberg.de/fossgis/home/-/issues/14
### Any questions or problems?
## Database model <img src="./img/grass_database.png" width=1200px align=center >
### Database - A normal directory which contains the data you process using GRASS GIS.
<img src="./img/grass_database.png" width=500px align=right > ### Location - A location is a directory with data related to a certain geographic location or a certain project. - A location is defined by its coordinate reference system and geographical boundaries. - All data within one location must have the same coordinate reference system.
<img src="./img/grass_database.png" width=400px align=right > ### Mapset - A location contains mapsets. - Each mapset contains data related to a specific task or user. - A user can only work in one mapset at a time. - Every location contains a PERMANENT mapset. - The PERMANENT mapset is accessible from all mapsets, data in other mapsets is not accessible
<img src="./img/grass_database_dangerzon2.png" width=500px align=center > ### Danger Zone **Do not edit files within a location outside of GRASS GIS to avoid corrupting the data!** However, you can copy a location folder to share it with someone else.
### Create a new project and add data in the data tab <img src="./img/add_data.png" width=500px align=right >
<img src="./img/map_display_region.JPG" width=700px align=right > ### Region The region (marked in red) defines the geographic extent within which data is processed.
<img src="./img/cmd_region.png" width=500px align=right > ### Region The region can be printed and changed using the command `g.region` The **region** is defined by - the geographical projection - the geographical extent - the spatial resolution of cells (only relevant for raster data)
## GRASS GIS Commands <img src="./img/commands.png" width=1200px >
### Commands in GRASS GIS are separated into groups, e.g. <img src="./img/general.png" width=1000px align=left> <img src="./img/vector.png" width=700px align=left> <img src="./img/raster.png" width=1000px align=left>
### Documentation of each module → [https://grass.osgeo.org/grass84/manuals/index.html](https://grass.osgeo.org/grass84/manuals/index.html) <img src="./img/buffer_doc2.png" width=1800px align=center>
### Execute commands from the GRASS GIS command line <img src="./img/grass_cmd.JPG" width=1200px align=center >
### Execute commands from the GRASS GIS console <img src="./img/console.JPG" width=400px align=center >
### Execute commands using graphical user interface <img src="./img/layer_manager_commands.png" width=700px align=center >
### Execute commands using graphical user interface <img src="./img/buffer_tool.JPG" width=500px align=center >
### Data of the mapsets are displayed in the "Data" tab <img src="./img/data.JPG" width=200px align=center > - Click the **"reload" button** after you have processed data to update this view. - Double click data sets to visualise them in the map display window.
### Display Layers in the Map Display window All layers in the "Layers" tab are visualised in the Map Display window. You can have several Map Display windows. <img src="./img/layers.JPG" width=300px align=left > <img src="./img/map_display_region.JPG" width=450px align=right >
### Resources - [GRASS GIS 8.4 Manual](https://grass.osgeo.org/grass84/manuals/index.html) - [GRASS GIS introduction video](https://www.youtube.com/watch?v=ZeS7GT_Zlqg) - [Video Playlist: Getting Started with GRASS GIS](https://www.youtube.com/watch?v=56xkXMd9XBM&list=PLycBDiXWmuxnfLUjs1wkm6WvYsazeLZ0K)
## GRASS GIS exercise - Work on the exercises at http://fossgis.courses-pages.gistools.geog.uni-heidelberg.de/home/content/topics/06_grass/exercise.html