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GRASS GIS Quickstart

When launching GRASS GIS for the first time, you will open a default project "world_latlog_wgs84" where you can find a map layer called "country_boundaries" showing a world map in the WGS84 coordinate system.

GRASS Location Structure

Interface Overview

The GRASS GUI has several panels and tools:

  • Layer Manager: Controls loaded map layers.
  • Map Display: Shows raster/vector data.
  • Data Catalog: Displays the GRASS data hierarchy.
  • Console: Run GRASS commands directly.
  • Modules Search Bar: Search for specific tools and commands.

Getting Started with GRASS GIS

This section explains how to set up your working environment in GRASS GIS and import your geospatial data using command line

1. Create a GRASS Database Directory

Open a terminal and create a directory that will act as the GRASS GIS database:

# Linux, Mac, *BSD, ...:
mkdir -p ~/grassdata

# Windows
mkdir D:\grassdata

This directory will store all Locations and Mapsets.

This is the root directory that will contain all your GRASS locations and mapsets.

2. Launch GRASS GIS

Open GRASS GIS normally without a full path so you can create your first Location and Mapset using the GUI.

Search for GRASS GIS in the Start Menu and open it normally.

In the startup screen:

  • Set GIS Database to: ~/grassdata or D:\grassdata
  • Click on New next to Location
  • Choose one of the following:
    • Create with EPSG Code (e.g., 4326 for WGS84)
    • Import an existing raster/vector to define projection
  • Once the Location is created, you will be prompted to create your first Mapset (e.g., chirps_pcp)

3. Create a New Location using command line

Use grass with the -c flag to create a new Location based on a coordinate reference system (CRS). 

# Linux, Mac, *BSD, ...:
grass -c EPSG:4326 ~/grassdata/myproject

# Windows
grass -c EPSG:4326:3 D:\grassdata\myproject
This command:

  • Creates a new Location named "myproject"
  • Uses EPSG:4326 (WGS 84 coordinate system)
  • Initializes the default PERMANENT mapset

4. Create and Start a New Mapset

Once your Location (e.g., myproject) is created, you can add a new Mapset to organize your analysis. 

# create a new mapset 
g.mapset -c mapset=chirps_pcp location=myproject

Notes: - Here, we are creating a mapset named chirps_pcp, which stands for CHIRPS Precipitation Data. We'll use this mapset for importing and analyzing precipitation datasets in upcoming sections. Download CHIRPS Annual Precipitation Data (2020–2024): https://data.chc.ucsb.edu/products/CHIRPS/v3.0/annual/global/tifs/

5. Launch GRASS into the new mapset:

# Mac/Linux
grass --text ~/grassdata/myproject/chirps_pcp

# Windows
grass --text D:\grassdata\myproject\chirps_pcp

Notes: - The new mapset must be inside an existing location.

Additional Mapset Operations

List all available mapsets 

g.mapsets -l

Switch to a different mapset within the same location 

g.mapset mapset=ind_annual_data

Sample Data

To follow along with the upcoming tutorials, please download the following sample datasets:

In this section, we:

  • Set up the GRASS GIS database structure
  • Created a Location and Mapset
  • Prepared to work with CHIRPS precipitation data

👉 In the next section, we’ll learn how to import raster and vector data into your mapset and begin your analysis!