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AI-Assisted GIS Workflows

Modern generative AI assistants help GIS professionals automate batch tasks, formulate complex query expressions, and write and troubleshoot scripts.

1. PyQGIS Scripting and Batch Processing

The Python API in QGIS (PyQGIS) allows running any processing tool programmatically and managing project layers.

  • Accessing the Python Console:

    Open QGIS. Go to Plugins > Python Console to access the interactive shell and editor.

  • Basic Python Script Structure:

    The script below loops through a folder of raster elevation files and clips each to a study boundary shapefile:

import os
from qgis.core import QgsProject
import processing

# Define directories
input_folder = "/Users/krishnaglodha/Documents/work/wb/QGIS-WECS/data/raw_rasters/"
mask_layer = "/Users/krishnaglodha/Documents/work/wb/QGIS-WECS/data/boundary.gpkg"
output_folder = "/Users/krishnaglodha/Documents/work/wb/QGIS-WECS/data/clipped/"

# Create output folder if it doesn't exist
os.makedirs(output_folder, exist_ok=True)

# Loop and run GDAL clip
for filename in os.listdir(input_folder):
    if filename.endswith(".tif"):
        input_path = os.path.join(input_folder, filename)
        output_path = os.path.join(output_folder, "clipped_" + filename)

        params = {
            'INPUT': input_path,
            'MASK': mask_layer,
            'NODATA': -9999,
            'OUTPUT': output_path
        }

        processing.run("gdal:cliprasterbymasklayer", params)
        print(f"Successfully clipped: {filename}")

2. Prompting for Spatial SQL and GIS Expressions

When asking an AI assistant to generate expressions or queries, you must provide detailed context (schema names, field types, and target goals).

  • Weak Prompt:

    "Write a SQL query to intersect rivers and buffers."

  • Effective AI Prompt:

    "I am working in a PostGIS spatial database. I have a vector table of rivers (public.rivers_line) with geometry column geom and attribute field scalerank (integer). I also have a district boundaries table (public.districts_poly) with geometry geom and name attribute district_name. Write a spatial SQL query to find the total length of major rivers (scalerank <= 3) that flow inside the district named 'Kathmandu'."

  • AI-Generated PostGIS SQL Output:

    SELECT 
    d.district_name,
    SUM(ST_Length(ST_Intersection(r.geom, d.geom))) / 1000.0 AS river_length_km
FROM 
    public.rivers_line AS r,
    public.districts_poly AS d
WHERE 
    d.district_name = 'Kathmandu'
    AND r.scalerank <= 3
    AND ST_Intersects(r.geom, d.geom)
GROUP BY 
    d.district_name;

3. Troubleshooting Common GIS Programming Errors

AI assistants can identify and resolve common bugs that occur during automation.

  • Projection Mismatch Errors:

    Error symptoms: Spatial queries return \(0\) features or incorrect distances because layers are in different CRS (e.g. comparing WGS84 coordinates to UTM meters).

    Solution: Reproject layers to a common CRS (using ST_Transform in SQL or QgsCoordinateTransform in Python) before running overlay functions.

  • Invalid Geometries:

    Error symptoms: Buffer or Union operations fail with self-intersection errors.

    Solution: Run the QGIS Fix Geometries tool, or run ST_MakeValid(geom) in PostGIS.

  • File Lock Issues:

    Error symptoms: Python throws PermissionError when trying to overwrite a shapefile.

    Solution: QGIS locks active project layers. Remove the layer from the QGIS active canvas (QgsProject.instance().removeMapLayer(layer)) before overwriting it.