{"id":1306,"date":"2013-12-12T16:49:22","date_gmt":"2013-12-12T15:49:22","guid":{"rendered":"http:\/\/geowww.agrocampus-ouest.fr\/web\/?p=1306"},"modified":"2022-01-18T15:50:15","modified_gmt":"2022-01-18T14:50:15","slug":"watershed-tool-howto","status":"publish","type":"post","link":"https:\/\/geosas.fr\/web\/?p=1306","title":{"rendered":"The watershed (WS) tool – Howto and How"},"content":{"rendered":"

\"\"<\/a>\"\"<\/a>The WS tool: Howto<\/h1>\n


\n<\/a>
\n\"\"<\/a>version fran\u00e7aise
\nici<\/a><\/p>\n

Access<\/h2>\n

The Watershed Tool (WT) is meant to be simple of use. No software needs to be installed nor database provided. Only the URL of the service-providing website is required.
\nThe WT is provided as an addon to geOrchestra’s viewer.
\nIt can be found either on the toolbar<\/strong>:\"\"<\/p>\n

or in the \u00ab\u00a0Tools\u00a0\u00bb menu<\/strong>:\"\"<\/p>\n

If not pre-loaded into the viewer it has to be selected from menu \u00ab\u00a0Tools\/Manage tools\u00a0\u00bb<\/strong>:<\/p>\n

\"\"<\/a><\/p>\n

Parametrising<\/h2>\n

The WT can be parametrised using menu \"\"\/ Parameters<\/strong>. One can select, the DEM used for computation out of a list, the computed catchment’s minimal area, the watershed’s smoothing mode of delineation, automatic vs. no zoom on resulting layer extent. Default parameters are fit for Brittany.<\/p>\n

Execution<\/h2>\n

The watershed is computed from menu \"\"<\/strong> with one out of four possible input types corresponding to lines 1-4 of the menu :<\/p>\n

\"\"<\/a><\/p>\n

    \n
  1. clicking on the map provides the associated coordinates (x,y);<\/li>\n
  2. selecting point objects (as outlets) from a WMS layer (or a reference to a WMS layer_ provided by a third-party OGC server;<\/li>\n
  3. a reference to a whole WMS point-layer (in this case the data are circulated between the WPS and the cartofgraphic server, to the exclusion of the client) ;<\/li>\n
  4. a GML file (point list) in the maps’s current coordinate reference system (SRS), i.e. the french Lambert 93 by default, directly imported by the user into the viewer.<\/li>\n<\/ol>\n

    in addition, one can tune the parameters (a. select the DEM used for computation, smooth\/unsmooth the result, zoom to result vs no zoom), access the service’s metadata (b.), or display this help file (c.).<\/p>\n

    Result<\/h2>\n

    Once processed the resulting layer is automatically uploaded onto a dedicated OGC server then added as WMS to the viewer. Thus it benefits from the client’s (viewer) funcionalities, hence: display (WMS<\/a>), download as a SHAPE file (WFS<\/a>), spatial and attribute requesting tools (WMS\/WFS), styling (SLD<\/a>), context saving (WMC<\/a>), etc.
    \n    \"\"<\/a><\/p>\n

    \"\"<\/a>How: the WS tool (Addon and WPS) as it works<\/h1>\n

    Client to\/from serverdata flows depending on input<\/h2>\n

    To better understand the OGC traffic we provide a diagram (below) for each type of input. These are followed by a table summarising it all.<\/p>\n

    Functional diagram<\/h2>\n

    The figures below expose the succession of OGC flows between the components of the SDI, depending on the selected input option:<\/p>\n