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Installing Python packages in QGIS 3 (for Windows)
Python is in the heart of QGIS (or in the guts if you prefer), which enables us to use tons of third party Python libraries. In Linux systems, QGIS will…
Posted inQGIS plugins
Visibility analysis for QGIS 3.0 : tackling big data
Viewshed plugin for QGIS is based on Numpy library for handling raster data. Numpy is tuned for high performance and is (relatively) easy to use. However, it relies heavily on…
Posted inSpatial analysis & GIS
Land visibility in the Mediterranean: a large scale model
Visibility of land was a major consideration for ancient seafaring, for reasons of navigation and security. Even if the open sea travel must have been practised already by the Neolithic…
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Natural places and archaeology
First time I heard of something like “natural places” was some ten years ago at a conference in Slovenia. Several, mostly young researchers were proud to demonstrate an existence of…
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Lissage du modèle numérique de terrain BD ALTI
Le problème n’est pas nouveau, mais on ne trouve toujours pas de solutions simples pour le « maquillage » du modèle numérique de terrain (MNT) très couramment utilisé en France,…
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Benchmarking viewshed algorithm: Nuraghi of Sardinia
The new viewshed plugin for QGIS 3 features an improved algorithm which should result in perceptible improvements in terms of efficiency. So let’s give it a try! Nuraghe in Toralba-Sant'Antine…
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Looping through numpy arrays (e.g. moving/rolling window)
Numpy is the cornerstone of matrix based calculations in QGIS (and elsewhere). It does wonders with raster data (unless it hits the limit of available live memory…). A recurrent problem…
Posted inQGIS plugins
Visibility analysis for QGIS 3.0
Visibility analysis plugin is now available in QGIS 3.0! It has been completely refurbished: from now on it will be integrated into the “Processing toolbox”. This is a more appropriate…
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Tanaka method or how to make shaded contour lines
Contour lines have become a commonplace, unassuming companion of our cartographic outputs - GIS has made us forget their visual potential. Already in the 19th century cartographers experimented with shaded…
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My first QGIS map: the aid from Cyrene
Cyrene, Lybia Sometime during the reign of Alexander of Macedon a famine broke out in Greece. We don’t have many documents reporting the gravity of situation; apparently Greece was suffering…