Using the Digitizer

The Digitizer page allows you to create polylines and polygons that define particular features on a map.  These could be boundaries, sites, reserves or areas of interest for example.  Basically you just click on the map to create a line connecting successive points that follow some feature.  Polylines are any line of two or more points and Polygons are similar but closed 'shapes' with the first point joining the last.  Once you have created your feature you can output this so it can be used in other programs.  You can also use this page to check route lengths and region areas from your lines or shapes simply by clicking them.  This page explains how to use these functions and the Useful Tips below are particularly recommended.

Note: If you are not logged-on then the page works in public mode where everyone shares a common collection of polylines.  If you are logged-on you can save and see just your own of collection polylines.  In both modes all functionality is available.

Useful Tips:

  • Before starting a new line, navigate on the map to your area of interest and set the zoom to a sensible view.
  • You can click 'quick locate' (top right of map) to quickly go to a named location or grid-reference.
  • Typically you would also wish to switch to the 'Satellite' view to use natural features as guides.
  • It is a good idea to very roughly outline your area first and then move (drag), add and delete points as needed at a more zoomed view.  It is much easier and quicker to adjust your line by editing rather than trying to place points accurately first time.
  • When not drawing points (after choosing to 'stop drawing') you can freely edit points by dragging them with your mouse.  Also, when you re-open an existing line it is immediately available for editing.
  • If you move (drag and drop) any control point (which are midway between two vertices) this will automatically create a new vertex.  This is useful for adding detail and modifying your line without manually adding new points.
  • Click to Save regularly.  Any changes you make are not saved until you click this button.
  • Once you have created your feature, you can export this by clicking 'Output Data' at the bottom of the page which will take you to the Exporter.


The top row of controls allow you to:

Choose an existing feature to view or edit from the drop down list.

start new line - will prompt you for a name for a new line or polygon.  You can then start to add points - just click the map to successively add points.  If you have unsaved changes to any existing work you will be warned.  Names can be 64 characters maximum and can only contain alphabetic, numeric, space or the special characters ' - : , ( and ).

reload line - re-loads the current line.  If you have unsaved changes to your line you will be warned.

delete line - will permanently remove the current line.  You will be prompted to confirm this action.

save copy as - saves an identical copy of the current line under a new name and opens this for editing.  The original line is saved.

Map Working Area

Within the main map area you can zoom in or out using the + and - button at the top left, or use your mouse scroll wheel.  You can switch between background views with the buttons at the top right.  Scroll the map by dragging it with your mouse down.

Current mouse position is reported in the cursor immediately below the map.  This shows National Grid and (Latitude, Longitude) in decimal degrees and works in both GB and Irish systems as applicable.

Edit Buttons

The row of buttons below the map provide the following edit functions:

undo last - will undo the last edit to your line (drag/move point, add point, delete point).

continue line - will continue your line from the last point drawn.  You can use this in conjunction with 'stop drawing' to continue work later.

stop drawing - will stop drawing mode and allow editing.  'Stop drawing' also cancels the add and delete point actions.

add point - allows you to add a new point (or vertex) anywhere on your line.  Note you need to click this button and then click the line where you wish to insert a new point.  You can then drag this point to any new position.  If you wish to cancel the 'add point' function click the 'stop drawing' button.

delete point - allows you to remove any existing point (or vertex) on your line.  Note you need to click this button and then click a point to remove it.  If you wish to cancel the 'delete point' function click the 'stop drawing' button.

close poly - completes the line by joining the last point to the first and renders as a filled polygon.  This also cancels drawing and puts the line in edit mode.

save changes - saves any outstanding changes.  When the current line is saved, information about the current map mode (Normal, Satellite or Hybrid) is also saved as your preferred drafting background.  Remember to save changes regularly and when done.

'view as polygon' Option

This option, situated below the edit buttons, will render your line as a closed and filled polygon.  You may wish to select this option prior to starting to digitize a new area if this is a closed shape.  You can change this view at any time.

For lines with a large number of points, it is quicker to edit with this option off.

If viewing as a polygon, you can click inside your shape and have the area reported by the map cursor (immediately below the map).  If not in polygon mode, you can click your line to have the length reported by the map cursor.  In either mode, you can click any point on to have information about that point displayed by the cursor.

'show other features' Option

By selecting this option you will see a list of all your (or public) existing map features.  You can tick any of these to add them to your current map.  This is useful if drawing compartments within a site or when digitizing adjacent or segmented lines or areas.  You can remove a feature by un-ticking it.  De-select this option to remove all added features.

Overlays are always shown as outlines and your map settings (zoom, position and view) are unchanged.

'Output Data' Link

Click this link to go to the Exporter page where you can output point data from this or any other line.