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Posts by TerraLab

Multispectral vs Hyperspectral: Bands, Cost and Free Data

Multispectral records 4 to 13 wide bands, hyperspectral 100 to 300 narrow ones. A table of bands, free satellites, drone sensor cost and data size.
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Plot Plan vs Site Plan: The 8 Items 19 Permit Offices Check

A plot plan draws one lot, a site plan the whole project. The 8 items 19 US permit checklists ask for, who can draw a plot plan, and how to make one in QGIS.
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Orthophoto vs Orthomosaic: The Difference, and 7 Free for QGIS

An orthophoto is one corrected photo; an orthomosaic stitches many. How each is made, why one drew Berlin's TV tower 127 m off, and 7 free national services.
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Semantic vs Instance vs Panoptic Segmentation: The Difference

Semantic segmentation labels every pixel with a class: building or not. Instance segmentation draws every building as its own object.
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AI Agent for QGIS: The Complete Guide

How to use AI Agent in QGIS: install it, write your first request, find examples and data sources, stay in control, then 5 real tasks, from open data to an HTML report.
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Greenfield vs Brownfield Sites: Meaning, Costs, How to Spot Them

A greenfield site was never built on; a brownfield site was, and may hold slabs or pollution. What each costs, how it looks from the air, 314 sites counted.
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How to Add a Basemap in QGIS: XYZ, WMS, QuickMapServices

Browser panel > XYZ Tiles > double-click OpenStreetMap. Then satellite tiles by URL, QuickMapServices, a national WMS, and the ground size of each zoom.
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DSM vs DTM vs DEM: The Difference, Measured, and Free Downloads

A DSM is the top of everything, a DTM bare ground, a DEM either. On one town tile the DSM made 41% of the ground steeper than 30°, the DTM 7%. 8 free sources.
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Colored site plan: the same block four ways

Flat, watercolor, pencil and glossy, all rendered from one aerial image of Letchworth Garden City. Every prompt in full, and where the model invented water.
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Detect Solar Panels in QGIS: 5 Methods

Check OpenStreetMap first. Then four ways to map rooftop PV from aerial imagery in QGIS, with the menu paths and where each one fails.
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