GRASS GIS Basics

Now that you've created your Location and Mapset, you're ready to start using GRASS GIS to import data, visualize layers, and perform basic GIS operations.

This chapter covers:

Importing raster and vector data
Viewing and managing layers
Setting the computational region
Accessing metadata
Removing/exporting data

1. Import Raster Data

To bring in external raster files like .tif:

r.import input=/path/to/chirps-v3.0.2024.tif output=chirps_pcp_a_2024

Bulk Import Example:

## macOS/Linux
for file in /path/to/folder/*.tif; do
  name=$(basename "$file" .tif)
  r.import input="$file" output="$name"
done

## Windows – PowerShell
Get-ChildItem "D:\path\to\folder\*.tif" | ForEach-Object {
  $name = $_.BaseName
  r.import input=$_.FullName output=$name
}

2. Import Vector Data

To import shapefiles or other vector formats:

v.import input=/path/to/IndiaBoundary.geojson output=IndiaBoundary

Bulk Import Example:

## macOS/Linux
for file in /path/to/folder/*.shp; do
  name=$(basename "$file" .shp)
  v.import input="$file" output="$name"
done

## Windows – PowerShell
Get-ChildItem "D:\path\to\folder\*.shp" | ForEach-Object {
  $name = $_.BaseName
  v.import input=$_.FullName output=$name
}

After importing the CHIRPS raster and the IndiaBoundary.geojson, your GRASS GIS environment will be organized into a Location, Mapset, and the corresponding imported datasets.

You should see a structure similar to this in the Data Catalog:

GRASS Location Structure

3. Display Layers in GUI

To visualize data: - Use Layer Manager to add raster/vector layers - Right-click → Properties to style (color, opacity, etc.)

Or from command line:

d.rast map=my_raster
d.vect map=my_vector

4. Set the Computational Region (Optional)

GRASS GIS performs all analysis within the current region extent and resolution.

# Match region to a raster:
g.region raster=<existing_raster>
# or
g.region vector=<existing_vector>

# Set Resolution
g.region res=0.003

# To manually set region boundaries and resolution:
g.region n=25 s=10 e=90 w=70 res=0.01 -p