"The explosive growth of the GeoWeb and geographic information has made GIS powerful media for the general public to communicate, but perhaps more importantly, GIS have also become media for constructive dialogs and interactions about social issues." - Sui & Goodchild
Carto.com offre un frontale très convivial pour piloter une base de données spatiale utilisant PostGIS (http://postgis.net, https://carto.com/docs/faqs/postgresql-and-postgis). Rapide découverte en deux parties.
Avant de commencer, il faut se connecter sur http://carto.com avec le utilisateur geoinf16.
On utilise la géotable earthquakes (source : http://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_month.csv)
SELECT ST_AsText(the_geom), * FROM earthquakes
SELECT ST_AsText(ST_Transform(ST_GeometryFromText('POINT(558000 137000)', 21781), 4326))
INSERT INTO earthquakes (place, mag, the_geom) VALUES ('SOMEWHERE, Switzerland', MMM, ST_Transform(ST_GeometryFromText('POINT(XXX YYY)', 21781), 4326));
SELECT ST_Distance( ST_GeomFromText('POINT(-72.1235 42.3521)',4326), ST_GeomFromText('LINESTRING(-72.1260 42.45, -72.123 42.1546)', 4326) )
SELECT *, ST_Distance( the_geom::geography, ST_GeometryFromText('POINT(141.0357 37.4217)',4326)::geography ) / 1000 as d FROM earthquakes
SELECT *, ST_Distance( the_geom::geography, ST_GeometryFromText('POINT(141.0357 37.4217)',4326)::geography ) / 1000 as d FROM earthquakes WHERE mag > 6 ORDER BY d LIMIT 1
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On utilise les deux géotables highway61 et musicians (sources : https://carto.com/academy/d/highway_61.geojson, https://carto.com/academy/d/mississippi_blues_musicians.geojson).
SELECT ST_Buffer(the_geom_webmercator, 50000) as the_geom_webmercator FROM highway61
SELECT ST_Intersects( ST_GeomFromText('LINESTRING(-2 -2, 2 2)', 4326), ST_GeomFromText('POINT(0 0)', 4326) )
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