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Help of side-by-side maps

Three tools were developed to compare indicators more easily than overlaying layers in EDO MapViewer.
Those tools use side-by-side maps and are named Compare Indicators, Compare Dates and Compare Layers.
Compare Indicators and Compare Dates don’t differ in functionalities but only in the content they show within four maps placed side-by-side: Compare Indicators displays four different indicators at the same time, while Compare Dates displays snapshots of the same indicator at four different moments in time. Both haven't a dedicated webpage but live as tabs within the Equal Area MapViewer.
Compare Layers merges the previous tools and allows to define all combinations among layers and times in this webpage.

Available layers are organized in three groups:

  • Archive (EDO): indicators provided by EDO for which time-based maps are available. The periodicity of maps can be by month or by 10-day period (dekad).
  • Archive (EDO Partners): indicators provided by EDO Partners for which time-based maps are available. The periodicity of maps can be by month or by 10-day period (dekad).
  • Last Available (EDO): indicators provided by EDO for which only the map of the date when they were last calculated is available. They are disabled by default in Compare Dates, but their visualization can be enabled by the user.

All these three side-by-side maps tools have the following functionalities:

  • Selection of the global parameter by dropdown menus: the global parameter is the date for Compare Indicators and the indicator for Compare Dates.
  • Four OpenLayers-based maps, provided with legend (turned off by default), pan, and zoom controls (zoom in, zoom out, zoom to North, zoom to East, zoom to South, zoom to West, zoom by rectangle, zoom to full extent, zoom to country).
  • Synchronization of pan and zoom on four maps: if the user navigates one of the maps, the same operation is done on the others; this function is enabled by default, but it is possible to turn it off.
  • Possibility to display a graph of the selected indicator instead of a map: the graph is done calculating the values of the indicator at the map centroid (displayed in the maps) and covers a user-defined period (one year by default).
  • Sketching on Map1: the user can draw a point, a line or a polygon on Map1 (the map at top-left corner) to identify a region of interest; that region is automatically drawn also on the others maps: in this ways the user can check if the phenomenon highlighted in Map1 is present also in the other maps.
  • Switching between Compare Indicators and Compare Dates, initializing the page or keeping the same geographical extent.

A list of icons to use tools available in side-by-side maps follows.
icon of CheckSnapshotMaps (25) Check availability of time snapshot maps
Click this icon to check the availability of snapshots maps for a user-defined temporal range.

icon of Warning (29) Warning
Click this icon to open important warnings

icon of Help (30) Help
Click this icon to open this help.

icon of Refresh (31) Refresh
Click this icon to refresh a single map or all maps. This icon is hidden by default and itis displayed only to suggest a refresh action.

icon of Recentre North (32) Recentre North
Click this icon to recentre the map towards North. The new map will be centred in the middle point of the Northern border of the current map.

icon of Recentre South (33) Recentre South
Click this icon to recentre the map towards South. The new map will be centred in the middle point of the Southern border of the current map.

icon of Recentre East (34) Recentre East
Click this icon to recentre the map towards East. The new map will be centred in the middle point of the Eastern border of the current map.

icon of Recentre West (35) Recentre West
Click this icon to recentre the map towards West. The new map will be centred in the middle point of the Western border of the current map.

icon of Zoom In (36) Zoom In
Click this icon to activate the function and then click a point on the map: the map is zoomed in 2 times around the clicked point.

icon of Full Extent (37) Full Extent
Click this icon to go to the maximum available map extent.

icon of Zoom Out (38) Zoom Out
Click this icon to activate the function and then click a point on the map: the map is zoomed out 2 times around the clicked point.

icon of Pan (39) Pan: Drag and Move Map
Click this icon to move the map with the mouse choosing your favourite view.

icon of Zoom by Rectangle (40) Zoom Rectangle
Click this icon to draw a rectangle on the map: the map is zoomed in accordance to the closest OpenLayers zoom level.

icon of 1-month Delay (41) 1-month delay
This icon is shown only when a map of a layer with 1-month delay is displayed

icon of Layer switcher (42) Legend
Click this icon to open the OpenLayers layer switcher (i.e. legend)

icon of Toggle to graph (43) Toggle to graph
Click this icon to toggle from map to graph

icon of Toggle to map (44) Toggle to map
Click this icon to toggle from graph to map

icon of Sketch point (45) Sketch a point
Click this icon to sketch a point on map 1

icon of Sketch line (46) Sketch a line
Click this icon to sketch a line on map 1

icon of Sketch polygon (47) Sketch a polygon
Click this icon to sketch a polygon on map 1

icon of Refresh (62) Credits
Click this icon to open a dialog box showing credits on data and layers used in the four maps.


For more information or to leave feedback
please contact Alfred de Jager