Areas are one of four main data types in the Spatial Portal, along with species (taxa), layers and facets. Area can be defined by 14 different options. When an area gets defined, it is added to the map; a new layer is added to the layers list. Areas form the basis of most Spatial Portal operations either explicitly (by explicit definition) or implicitly (by defaulting to current map extents).
Areas are a persistent option associated with the display or analysis of species (taxa).
NOTE: In dealing with complex areas that are either pre-existing in the Spatial Portal, created interactively or imported, or generated from an area merge, the area boundaries may be generalised. The reason for this is that the system has limitations on the number of vertices that can be readily processed through ALA functions. If the area is above the threshold, you will be given a warning that the area will be generalized to fit the limits.
In addition to specifying an area as the starting point for analysis, the analysis tools (see the Tools menu) require a defined area – this help text also relates to the area selection process used within these analysis tools. There are sixteen ways to generate and map an area (grouped into five main categories):
To define an area, select Add to map | Area.
The Add area dialogue will open. By default the Draw bounding box option is selected.
Interact with the map
Interact with the map – this group of functions allows the user to draw a region directly within the Spatial Portal. Sub-options available include drawing:
- a bounding box,
- a polygon,
- a point and radius, or
- to select a pre-defined polygon area from a contextual layer that has already been mapped.
NOTE: you should either zoom and pan to the area of interest before selecting to draw the bounding box or polygon, or after the pop-up box appears – use the Google slider and direction functions to the left of the map as dragging operations will not work when the portal is looking for mouse operations on the map.
Draw bounding box
Draw a bounding box by holding down the left mouse button and dragging out a rectangle.
NOTE: When the cursor goes over the Quick Links, Scale Bar or Hover boxes, it will disappear. Therefore, zoom and pan so that none of these boxes are in the way of the bounding box vertices.
Click Next to complete the bounding box layer. The image will zoom to the area selected.
Draw a polygon by clicking the left mouse button at the first point, then add vertices of the polygon by left-clicking each point. Return to the first point and click to complete the shape.
Click Next to complete the polygon layer. The image will zoom to the area selected.
Draw point and radius
Draw a circular area by:
- clicking the left mouse button at the centre of the circle,
- drag outwards holding the left mouse button down to expand the circle,
- release the button to create the circle.
NOTE: The radius of the circle will be (dynamically) displayed next to the cursor as you drag out the radius.
Click Next to complete the circular layer. The image will zoom to the area selected.
Select Area from Polygonal Layer
Select an area from a polygonal layer either by typing in the autocomplete text field, or by navigating the hierarchical tree of polygonal (contextual) categories.
Left mouse click to select a polygon on the map
Draw Polyline with buffer
This function allows you to draw a line with multiple points and define a area around the line.
NOTE: You must click on each point in the line, and finish with a double click. Do not click and drag to draw a line as this will pan the map instead.
The default buffer is 10 kms.
Click each point along the line.
Double click to complete the line.
Click Next to finalise the area layer.
Search for a street address using by typing in the beginning of the address.
Once you have found your address, define a radius in kilometres (default is 10 km). Click Next to add the location as a layer to the map. The image will zoom to the area selected.
You can change the name of the My Area in the first text field. Features such as Queensland Museum and Sydney Opera House are also supported.
Create radius from point (using latitude, longitude and radius)
This option requires that you enter:
- A longitude in decimal degrees
- A latitude in decimal degrees
- A radius in kilometres
- Optionally, a name for the area
Click Next to add the location as a layer to the map. The image will zoom to the area selected.
The ALA Gazetteer has over a 600,000 named areas that can be added to the map. For a complete list of Spatial Portal contextual gazetteer layers that support gazetteer (named areas), see to http://spatial.ala.org.au/layers.
Start typing the place name you are interested in. The Gazetteer autocomplete will provide possible matches. As there are a large range of options, you can choose to narrow the search to specific sources, or scroll to the bottom of the list to choose actual values.
Select the place name and click Next. The location will be created as a layer and the image will zoom to the selected area.
Preset Areas allow the user to select:
- the world
- the current map view.
With this option a bounding box is drawn around most of the world.
However, the standard projection used by the Spatial Portal does not permit the use of a bounding box > ~85 degrees north and south of the equator. More info »
The Australian bounding box only covers mainland Australia, including Tasmania. It does not include Australian territorial islands and the Australian subantarctic islands or the Australian Exclusive Economic Zone. The bounding box captures Australia waters off Papua New Guinea and intersects with the lower bottom edge of Papua New Guinea, Timor-Leste and a couple of southern Indonesian islands.
This option draws a bounding box that fills the current map extent. Whatever is visible in the map, whether you are zoomed in or out, is the current extent (view) of the map.
Click for more information on uploading a Shape File »
Click for more information on uploading a KML »
Other provides three additional mechanisms to define an area:
- define an environmental envelope,
- paste in a well known text (WKT) polygon definition
- merge a set of currently defined areas.
Define environmental envelope
An environmental envelope allows you to specify one or more environmental conditions to define an area on the map.
Where multiple environmental layers are used to define an environmental envelope, the definition of each added environmental layer condition is used to restrict the selected area rather than to enlarge it. In effect, it joins the conditions with an AND operator, so the addition of each condition will reduce the geographic area corresponding to the environmental envelope. The limit to the number of layers added is the total number of environmental layers available in the Spatial Portal.
The key purpose behind this option is to help facilitate the identification of geographic areas where optimal ‘living conditions’ exist for flora and fauna. For example, ‘optimal’ locations for growing a particular grape variety may be identified, if the known parameters exist within the Spatial Portal layers. The list of layers is available here.
You can start typing words in the layer name to get a list of matching layers to select from:
Select the layer and enter the parameters for your envelope. The envelope will preview on the map. Click Next.
A single Environmental layer has been added to the Map to show Annual Mean Temperature between 22 and 26 degrees.
Note that only one set of contiguous values can be defined for each added layer. For example, a mean annual temperature between 15 and 20c is acceptable but <10c and >15c is not. Re-adding a layer with different lower and upper limits will only ‘cookie cut’ the original envelope/area and not add to it.
A second environmental layer has been added to the Map to show Annual Mean Precipitation between 500 and 1000ml, the Map now highlights only those areas where the 2 applied environmental layers co-exist.
Paste Well Known Text (WKT)
Click for more information on uploading a WKT »
Merge map areas
This is a new option that permits a set of predefined areas (each defined by a layer on the top-left of the Spatial Portal window) to be merged into one new layer that contains all the areas. This allows for great flexibility in defining areas. For example, an ‘area’ could be made of up a number of discrete IBRA regions, or imported areas combined with areas defined in the Spatial Portal.
To merge areas, first add them individually to the spatial portal. Then choose the option Add to map | Area | Merge map areas. You will then be asked which layers you want to merge and whether you want to merge them with a Union (add both areas together) or an Intersection (retain only the shared area).
In the example below, the circle and the rectangle have been merged with a union.