Several weeks ago I stumbled upon an amusing article on a museum displaying pebbles and rocks resembling human faces, situated in Chichibu, Japan. The stones are called jinmenseki (珍石) and one should be able to recognise human faces in their naturally occurring dents and holes. The founder of the museum,...
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Pebbles, faces and landscapes:
Some thoughts on hillshade models for Lidar analysis
Hillshade modelling is a standard form of terrain representation in cartography. The idea is to simulate lighting of a terrain from a certain direction (or multiple directions). The method is well known and constantly improved in GIS – as means of cartographic representation. It seems, indeed, difficult to imagine spatial...
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Depth below horizon: new (old) functionality for QGIS viewshed analysis
The basic idea of visibility analysis is to test whether particular locations are theoretically observable from a given observer point (« theoretically » because our data and algorithms can never ideally replicate real-world situations). Such a query yields a yes/no answer for each tested point, which is typically represented as...
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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 use the main Python installation, but in Windows things get more complicated. QGIS has it’s own Python, which means we...
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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 available live memory and will break with voluminous datasets. Which is what elevation models usually are…
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