Tag: guide

An orthophoto is one aerial photograph corrected to a map. An orthomosaic is many of them stitched into one image. Which one you have, and where the seams are.

Semantic segmentation labels every pixel with a class: building or not. Instance segmentation draws every building as its own object. On a terraced street the difference is one polygon against forty.

A greenfield site has never been built on. A brownfield site has, and may still carry what the last use left behind. How to tell them apart in QGIS.

A DSM is the height of the top of everything: roofs, treetops, bare ground. A DTM is bare ground alone. Subtract one from the other to get what stands on it.

A building footprint is the outline where a building meets the ground. Most downloadable ones follow the roof. The difference, floor area, and the open data.

GeoAI is machine learning run on geographic data. The five things it extracts today, what it costs in hardware and time, and how to run it in QGIS.