Areas (Add to Map)

Areas (Add to Map)

  • By Lee Belbin
  •  January 30, 2012
  •  Tags:  spatial portal help

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).

Add to map options

Add to Map options

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.

As noted above, the analysis tools require a defined area – and all provide the facility to add a new area during a process – this help text also relates to the area selection process used within the analysis tools. There are thirteen ways to add an area to the map (grouped into five main categories):

Area options

 

Interact with the map

Interact with the map – 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 that you should either zoom and pan to the area of interest before digitizing, 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.

1. Draw bounding box

Draw a 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 bounging box vertices.

2. Draw polygon

Draw polygon

Draw a polygon by clicking the left mouse button at the first point, then add vertices of the polygon by left-clicking and double-click the left mouse button to finish

3. Draw point and radius

Draw point and radius

Draw a circlular area by clicking the left mouse button at the centre of the circle, then drag outwards holding the left mouse button down to expand the circle, then release the button to create the circle.

NOTE: The radius of the circle will be (dynamically) displayed on the top of the map window as you drag out the radius.

Point and radius added to the map

Your chosen Area will be added to the map and a Layer created

4. Select an Area from Mapped 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.

Click to select a polygonal region on the map

Left mouse click to select a polygon on the map

Searching

Searching – searching allows the user to create a point and radius based on a Google geocode (address) lookup or search for a pre-defined polygon using the ALA gazetteer service.

5. Radius Centered on Street Address or Known Facility

Search for a street address

Search for a street address using Google’s geocode lookup

Enter an address and press “Search”, a successful geocode lookup will allow you to define a radius in kilometres (default is 1km). Press “Next” to add the location to the map. 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.

Use the zoom to extent button (magnifying glass) in the layer options to zoom in to the new area as pictured below.

Street Address Zoomed_640

6.Create radius from point (latitude, longitude)

This option requires that you enter

  • The name of the area (this is what the layer produced will be called)
  • A longitude in decimal degrees
  • A latitude in decimal degrees
  • A radius in kilometers

Point Radius Options

A circular area with the specified radius is then generated at the specified location.

These options produce a Point Radius Result

7. Gazetteer polygon

The ALA Gazetteer has over a 600,000 named points 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/gazetteer.

Enter a place name from the ALA gazetteer

A gazetteer polygon, in this case the Australian Capital Territory, selected on the map

Australian Capital Territory_640

A gazetteer polygon, in this case the Australian Capital Territory, selected on the map

Preset Areas

Preset Areas – allows the user to select the entire world, just Australia or the current map view.

8. Box – Australia

A bounding box around Australia

A bounding box around Australia

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.

9. Box – World

Draws a bounding box around most of the world

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 »

10. Box – Current View (extent)

Current Extent_640

Draws a bounding box that fills the current map extents

Whatever is visible in the map, whether you are zoomed in or out, is the current view of the map. Also known as the current extent. Selecting Box – Current View draws a bounding box around this extent.

Upload

Upload – allows the user to upload either a zip file containing an ESRI shape file or Google Earth KML polygon definition.

11. Upload Shapefile

Click for more information on uploading a Shape File »

12. Upload KML

Click for more information on uploading a KML »

Other

Other – provides three additional mechanisms to define an area. Defining an environmental envelope, the ability to paste in a well known text (WKT) polygon definition and the ability to be able to MERGE a set of currently defined areas.

13. Define environmental envelope

An environmental envelope allows you to specify one or more environmental conditions to define an area on the map. The definition of each added environmental layer condition is ANDed: 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 with layers help by the Spatial Portal.Environmental Envelope_640

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.

Environmental Envelope 2_640

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.

14. Paste Well Known Text (WKT)

Click for more information on uploading a WKT »

15. 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 digitized polygons or imported with areas defined in the Spatial Portal.

The example below was generated by first digitzing three separate areas (rectangle, polygons and circle) and then using this option to combine the three separate areas into one new definition of area.

Merge areas

Merge three separate areas into one new definition of area