Importing cadastral data

tutorial

ecology

grass

python

Importing cadastral data with GRASS.

Author

Brendan Harmon

Published

August 30, 2026

Modified

August 30, 2026

Learn how to import cadastral data, extract a parcel, and set your computational region.

Data

Download parcels in geojson format from East Baton Rouge Parish’s Open Data Portal.

Setup

Start a GRASS session in a new project. Set the coordinate reference system for the project to Louisiana State Plane South using EPSG code 2801.

# Import modules
import sys
import subprocess
import numpy as np

# Find GRASS Python packages
sys.path.append(
  subprocess.check_output(
    ["grass", "--config", "python_path"],
    text=True
    ).strip()
  )

# Import GRASS packages
import grass.script as gs
import grass.jupyter as gj
from grass.tools import Tools

# Create GRASS project
gs.create_project("hilltop", epsg="2801", overwrite=True)

# Initialize GRASS session
gj.init("hilltop")
tools = Tools(overwrite=True)

# Print projection
projection = tools.g_proj(format="shell", flags="p").keyval
print(projection.get("name"))

Set computational region

# Set region
tools.g_region(n=206040, s=205640, e=1023700, w=1022100, res=1)

Import parcels

# Import parcels
tools.v_import(input="Tax_Parcel.geojson", output="parcels", extent="region")

Visualize parcels

# Visualize
m = gj.Map(width=1600)
m.d_vect(map="region", color="white", fill="black")
m.d_vect(map="contours", color="grey", size=0.5)
m.d_vect(map="parcels", color="white", fill="none", size=10)
m.show()

Extract parcel

# Extract parcel by ID
tools.v_extract(input="parcels", output="parcel", where="ID=26020")

# Extract parcel by address
tools.v_extract(input="parcels", output="parcel", where="PHYSICAL_ADDRESS='11855 HIGHLAND RD'")

Visualize parcel

# Visualize
m = gj.Map(width=1600)
m.d_vect(map="region", color="white", fill="black")
m.d_vect(map="parcels", color="grey", fill="none", size=1)
m.d_vect(map="parcel", color="white", fill="none", size=10)
m.show()

Set computational region

Set your computational region to the vector map with your parcel.

tools.g_region(vector="parcel")

Reuse

CC BY-SA 4.0

--- title: "Importing cadastral data" author: Brendan Harmon date: 2026-08-30 date-modified: today license: CC BY-SA categories: [tutorial, ecology, grass, python] description: > Importing cadastral data with GRASS. image: images/cadastre-01.webp bibliography: ecology.bib links: g_region: "[g.region](https://grass.osgeo.org/grass-stable/manuals/g.region.html)" format: ipynb: default html: toc: true code-tools: true code-copy: true engine: jupyter execute: eval: false jupyter: python3 --- ![Importing cadastral data](images/cadastre-01.webp) Learn how to import cadastral data, extract a parcel, and set your computational region. ::: {.callout-note title="Data"} Download [parcels](https://data-ebrgis.opendata.arcgis.com/datasets/0f69c6a9d0e944178799ccd834f4aec5_0/) in geojson format from East Baton Rouge Parish's Open Data Portal. ::: ## Setup Start a GRASS session in a new project. Set the coordinate reference system for the project to Louisiana State Plane South using EPSG code 2801. ```{python} # Import modules import sys import subprocess import numpy as np # Find GRASS Python packages sys.path.append( subprocess.check_output( ["grass", "--config", "python_path"], text=True ).strip() ) # Import GRASS packages import grass.script as gs import grass.jupyter as gj from grass.tools import Tools # Create GRASS project gs.create_project("hilltop", epsg="2801", overwrite=True) # Initialize GRASS session gj.init("hilltop") tools = Tools(overwrite=True) # Print projection projection = tools.g_proj(format="shell", flags="p").keyval print(projection.get("name")) ``` ## Set computational region ```{python} # Set region tools.g_region(n=206040, s=205640, e=1023700, w=1022100, res=1) ``` ## Import parcels ```{python} # Import parcels tools.v_import(input="Tax_Parcel.geojson", output="parcels", extent="region") ``` ## Visualize parcels ```{python} # Visualize m = gj.Map(width=1600) m.d_vect(map="region", color="white", fill="black") m.d_vect(map="contours", color="grey", size=0.5) m.d_vect(map="parcels", color="white", fill="none", size=10) m.show() ``` ![Parcels](images/cadastre-01.webp)   ## Extract parcel ```{python} # Extract parcel by ID tools.v_extract(input="parcels", output="parcel", where="ID=26020") ``` ```{python} # Extract parcel by address tools.v_extract(input="parcels", output="parcel", where="PHYSICAL_ADDRESS='11855 HIGHLAND RD'") ``` ## Visualize parcel ```{python} # Visualize m = gj.Map(width=1600) m.d_vect(map="region", color="white", fill="black") m.d_vect(map="parcels", color="grey", fill="none", size=1) m.d_vect(map="parcel", color="white", fill="none", size=10) m.show() ``` ![...](images/cadastre-02.webp) ## Set computational region Set your computational region to the vector map with your parcel. ```{python} tools.g_region(vector="parcel") ```