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Tag: geoai

Photogrammetry vs LiDAR: Which One for Which Job

Photogrammetry rebuilds a surface from overlapping photographs. LiDAR measures it with a laser. One gives you colour and a cheap flight, the other gives you the ground under the trees.
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Multispectral vs Hyperspectral Imagery, Explained

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, and what it costs.
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Orthomosaic vs Orthophoto: What Each Word Means

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.
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Semantic vs Instance Segmentation on Aerial Imagery

Semantic segmentation labels every pixel with a class: building or not. Instance segmentation draws every building as its own object.
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DSM vs DTM vs DEM: The Difference, and How to Tell

A DSM is the height of the top of everything: roofs, treetops, bare ground. A DTM is bare ground alone. DEM is the generic word, and usually means bare ground.
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How to Redesign a Street in QGIS: 5 Methods

Five ways to show a street rebuilt, from hand-drawn vector layers to a generated aerial view. Only one gives back a picture that stays on the map.
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How to Simulate a Flood in QGIS: 5 Methods

From the official hazard map to a generated aerial view of the water. Which method gives a number, which gives a picture, why an elevation model changes both.
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Convert Raster to Vector in QGIS: 5 Methods

For a classified raster, use Raster > Conversion > Polygonize. Here are the five methods, the fix for staircase edges, and what to do with a photograph.
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What Is a Building Footprint? Definition and Area

A building footprint is the ground area a building covers, measured at its outer walls. What counts, how to calculate it, how it differs from floor area.
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What Is GeoAI? Definition, Examples, Uses in QGIS

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.
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