L’échange de données entre institutions est une pierre angulaire des politiques de l’eau. QGEP est son homologue dédiée à la gestion des eaux usées et pluviales, initiée par le groupe utilisateur QGIS Suisse. QWAT est une application open source de gestion des réseaux d’eau potable émanant des collectivités de Pully, le SIGE à Vevey, Morges et Lausanne. And please have a look at our support offering for QGIS.
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We are already thinking about further improvments (ease authentification, better integration with processing…), so if you’re willing to fund them or just want to know more about QGIS, feel free to contact us at. Thanks so much to the GDAL and QGIS contributors for adding such a nice feature ! It brings lots of possibilities for organizations that have to deal with great number of big raster and just want to explore part of it. Note that the white flickering that you could see when you move in the map and the raster is refreshed should be removed in next version of QGIS according to this QEP. Your internet connection (mine, the one use for the video, is not an awesome one).The display latency that you could see in the video depends essentially on:
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While panning in the map, QGIS will download only few tiles from the image in order to cover the view extent.
© CNES 2018, Distribution Airbus DS Performances Here are the different steps you’d have to go through if you’re willing to navigate in a big raster image directly from the cloud. It is only HTTP requests, and everything else (rendering for instance) is done on the client side. The beauty of COG solution is its simplicity. The main advantages of the COG solution over WCS Server is that you don’t have to deal with the burden of deploying a server, like giving it ressources, configuring load balancing, handle updates, etc…
It’s completely possible to deploy a container or a VPS (Virtual Private Server) running a WCS Server in a cloud plateform. A WCS server can serve raw data according to a given geographic extent. Web Coverage Service standard could have been an option. Object storage allows to store and retrieve file as objects using HTTP GET/POST requests. We used a service provided by OpenStack, called Object Storage to serve the COG imagery. In addition to the HTTP/1.1 standard feature range request, it is possible to get specific tiles of an image through the network without downloading the entire raster. How it worksĪ COG file is a GEOTiff file which inner structure is tiled, meaning that the whole picture is divided in fixed size tile (256 x 256 pixels for instance) so you can efficiently retrieve parts of the raster. We chose to use a quite recent format managed by GDAL, the COG (Cloud Optimize Geotiff) and target OVH cloud platform for it provides OpenStack, a open source cloud computing platform. Using classic cartographic server standard like WMS or TMS is not an option because those services transform datasets in already rendered tiles. They want to access the image raw data, with no transformation, in order to fullfill deep analysis like instrument calibration.
We have recently been working for the French Space Agency ( CNES ) who needed to store and visualize satellite rasters in a cloud platform.
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