Posts by TerraLab

QuickOSM for a town, a Geofabrik .pbf for a country, Overpass Turbo for custom queries. Tested on Kisumu, with the timeouts and the ODbL credit.

Stream Sentinel-2 into QGIS over STAC with no account, or download the L2A product from Copernicus Browser. Bands, clouds and NDVI, tested in Brazil.

Open Layer > Georeferencer, place control points, pick Polynomial 1 and a projected CRS. Then read the RMSE in metres: tested on a 1947 USGS map.

Photogrammetry rebuilds a surface from overlapping photos. LiDAR measures it with a laser. One gives colour and a cheap flight, the other sees under the trees.

Multispectral imagery records a few wide bands of light. Hyperspectral records hundreds of narrow ones. What each can tell you about a field, a roof or a mine.

A plot plan draws one lot: its lines, its building, its setbacks. A site plan draws the whole project. Which one a permit asks for, and who draws it.

An orthomosaic is one map-corrected image stitched from many aerial photos. An orthophoto is one corrected photo. Which you have, and where seams go wrong.

Semantic segmentation labels every pixel with a class: building or not. Instance segmentation draws every building as its own object.

How to use AI Agent in QGIS: install it, write your first request, stay in control, then 10 real runs, from georeferencing an old map to an HTML report.

A greenfield site has never been built on. A brownfield site has, and may still hold slabs, sheds or contamination. What each costs and how to tell them apart.