How to Extract a New Map From a Slice of an Existing Map

Would you like to use just a portion of an Ortelius map or template for a new map? Ortelius 2 introduces three useful features to streamline your map production: ‘Slices’, ‘Extract Slice As New Document’, and ‘Reposition…’. ‘Slices’ lets you define smaller areas of a larger map that can be exported independently. ‘Extract Slice As New Document’ does just that — it exports all the drawing objects and layers covering just the area of the selected slice to a new Ortelius map file. ‘Reposition…’ allows you to change the new map’s drawing size, then resize and reposition the map content as desired. In this advanced tutorial, we’ll show you how to put them all together for your next map project.

Tutorial Details

  • Program : Ortelius 2
  • Difficulty: Advanced
  • Topics Covered: Slices, Extract Slice As New Document, Reposition…
  • Estimated Completion Time: med-long

Open an Existing Ortelius Map File

Start will an existing Ortelius map file. For this tutorial, we’ll create a map showing the countries that boarder the Adriatic Sea. Ortelius doesn’t have a template for the Adriatic Sea, but it does have a template that includes it! Start by opening the Europe map template.

  1. Choose ‘File > Templates > New From Template…’ from the main menu.
  2. Choose the template and click the button ‘New From Template’

Visible Map Layers

Ortelius’ map templates often have layers that are included but not visible by default (eye icon greyed out). You can explore these by toggling layers on and off. Since we are making a map of the Adriatic Sea, make the “Marine Areas” layer visible to show the feature of interest. You can turn on other layers and add/edit other features now, or wait to do so after you extract your new map. I prefer to wait to edit the smaller map.

To show hidden layers:

  1. The Layers tab in the right sidebar should be active (if it isn’t, click onto the Layers tab).
  2. Scroll down the layer list and click the ‘eye’ icon of layers to make them visible. Here we’ve turned on “Marine Areas” then zoomed in a bit to the Adriatic Sea.

Define Your Area of Interest with a Slice

Now the fun part. Let’s jump right into using the ‘Slices’ feature. Notice there is a “Slices” layer at the top of the layer stack? This layer is hidden by default. When the layer is active, the Tools palette automatically changes to reveal slice-specific tools. Let’s draw a slice to include the Adriatic Sea and adjacent countries.

  1. Click the “Slices” layer to make it the active layer. It will be visible (eye icon) and active (colored dot indicator).
  2. When the “Slices” layer is active, the ‘Slices’ tool palette automatically appears.
  3. Draw your slice from the upper left to lower right corner. As needed, use the ‘Select’ tool to reposition the slice, or grab the lower right slice handle to resize it.

Extract Slice As New Document

With the Slice still selected, choose ‘File > Extract Slice As New Document’. A new document opens containing a subset of all content from the original map.

A few things to note:

  • All settings for map scale, map area margins and drawing units from your original map are retained in your new drawing.
  • All objects completely within or intersecting the slice area are included in the new map, and those features that overlap the slice edges are not clipped (rather, they are just hidden off the drawing canvas).
  • All objects from the original map that are not contained within nor intersect the slice are completely removed from the new map. For example there is no Spain and no title.
  • The layer ‘show/hide’ settings are maintained from the original map.
  • Georeferencing information is retained from the original map if shapefiles were used, therefore shapefiles of matching coordinate reference system (CRS) settings may still be imported. Refer to the “Info” layer in the original map template for CRS information.
  • The new map is the same dimensions as the slice from which it was extracted (312 pt pt x 223 pt).


Changing the Dimensions of Your Map

What if the dimensions of your new map do not fit your requirements? As noted above, the new map is the same dimensions as the slice from which it was extracted (in this example, 312 pt pt x 312 pt). As needed, change the size of the drawing canvas. For example, we resize our map to fit neatly on an 8.5″ x 11″ printed page.

  1. Choose ‘File > Map Size & Units…’ from the main menu.
  2. Change ‘Drawing Units’ and canvas ‘Size’ as desired. Click “Subtract paper margins” if it needs sized for printer requirements.
  3. Click “OK”.


Spilled-over Features, Explained

When you change drawing canvas dimensions, the canvas expands (or contracts) to the right and bottom. As such, any content from the original map that intersected with the extracted slice area may now “spill-over” and be visible.

For example, in our map above, objects from the “Land” layer (shown in green) intersected our slice area. These happen to be entire land masses, so they are big objects. Since Ortelius does not clip objects when they intersect with the slices, the objects become visible when we enlarge the drawing canvas. Not a problem, but worth understanding why you may see “extra” objects unexpectedly spilling-over onto the drawing canvas.

Resize and Reposition Your Map

Let’s resize and reposition our map so the area of interest is centered on the drawing canvas.

  1. Choose ‘File > Reposition…‘ from the main menu. The Reposition bounding box is initially placed at the center of the page.
  2. If you need to change the starting point of the bounding box (as we have done above), hold the option key and drag it and/or drag its corner handles to move and resize it. When you release, you can continue to reposition your content.
  3. Drag the box to reposition your content. You will see the existing map position and semi-transparent overlay map image as reference while you drag.
  4. To resize the map, drag the bounding box corners. Hold the shift key to maintain the aspect ratio while resizing.
  5. Click the ‘Reposition’ button to commit your changes.

See it in action:

HINT: Changing the drawing size will change the map scale, therefore scale may need to be recalibrated.

Finish Editing Your Map

Good job! You’ve created a new map extracted from an existing map. Have fun customizing it.