More than 6,300 historical aerial photographs from Laval, Quebec were georeferenced into GIS-ready assets for urban and environmental analysis.
The challenge
The archive contained thousands of vintage aerial images without reliable coordinate references.
Faded imagery, physical distortion and time gaps required careful control point selection and RMSE management.
The approach
SBL used current orthoimagery and more than 25 control points per image to georeference photos from 1940 through 1990.
ArcGIS and QGIS workflows were used to validate GeoTIFF outputs and preserve control point metadata.
Reference
Select control points against current orthoimagery.
Align
Rectify vintage images in ArcGIS and QGIS workflows.
Package
Deliver GeoTIFF files and control point metadata.
The result
The city gained a GIS-ready record of urban change that could support planning, environmental review and historical analysis.
- More than 6,300 photos were georeferenced.
- The archive captured urban change from 1940 to 1990.
- RMSE was controlled below one for high-fidelity alignment.
- GeoTIFF outputs became compatible with municipal GIS workflows.