Creating a Map Outline

The other day I posted a tutorial on how to create a world map.  That tutorial however did not go over the initial first step of how to generate a map outline.  Ergo this followup post.

One method for creating a map outline is simply to draw it by hand, either on paper (which is then scanned and transferred to a graphics editing program) or by tablet.  However another method involves using fractal clouds native to graphics programs such as GIMP and Photoshop.  It is a fairly easy and straight forward process.  For the purposes of this tutorial I’ll be demonstrating how do this using GIMP, though the same general process applies to Photoshop as well.

Step 1: Create Layers

The first step will be to create the initial layers necessary to generating an outline in your graphics program.  Create a new file with the dimensions you wish the map to be sized at (in this demo piece I set the ‘Width’ to 2000px and the ‘Height’ to 1500px).  Make sure that the background color (under ‘Fill With’ in ‘Advanced Options’) is set to white, and hit ‘OK’.

Your new document will appear with a single white layer.  Rename this layer ‘Clouds’.  Now let’s turn the layer into fractal clouds.  To do so, select the layer and in the top menu go to ‘Filter’ > ‘Render’ > ‘Clouds’ > ‘Difference Clouds’.  A pop-up menu will appear called solid Noise.  Set the ‘Detail’ to 15 and then adjust the ‘X Size’ (horizontal axis) and ‘Y Size’ (vertical axis) to 8 or so.  If however, like me, you are working with a map whose dimensions are not even, you will need to use different sizes for X and Y in order for the clouds to be even (otherwise they will be distorted).  For instance I set the X Size to 10 and the Y Size to 8 for this example.  Next hit ‘OK’.  You should end up with something like this:

Next create a new layer above the ‘Clouds’ layer and name it ‘Grey’.  Fill this layer with 50% Grey.  To do so, change the foreground color to grey (50%) and then either use the ‘Bucket Fill’ tool to fill the image with grey, or simply click on the foreground color, then drag and drop it onto the image.  Now set the layer mode of this layer to ‘Lighten Only’.  This will cause anything lighter than the grey hue on the layer below to become visible, but will block out anything darker than it.  You should end up with something like this:

Step 2: Make Cloud Shapes

For this step we are going to turn these random puffs of fractal clouds into something resembling a land-form.  To do so click back on the ‘Clouds’ layer to select it.  Grab the Airbrush tool.  Change the foreground color to white and keep the background color at black.  Lower the opacity of the airbrush to 50% and change the brush size to about 200px (this will vary based on the size of the map, once you play around with this method you’ll get a feel for how large the brush should be).

What you will be doing here is airbrushing the ‘Clouds’ layer with white in the areas you want land to be, and black where you want the bodies of water to be.  This will take some time.  You may wish to adjust the size of the brush at times in order to move from broad brush strokes to more fine grained detail.  Here is an example of the progression:

Step 3: The Outline

Now it’s time to take these cloud shapes and make them into a two-tone image.  Click on the ‘Grey’ layer to select it, then ‘Right Click’ on that layer and in the drop down menu that appears select ‘New from Visible’.  This will create a new layer above the grey that essentially is a merged copy of all the visible layers below it.

Name this new layer ‘Outline’.  Next grab the ‘Select by Color’ tool, set the threshold to 15 and, on the ‘Outline’ layer, select the grey area (by left clicking on it) and then fill this area with black.  Now invert the selection: in the above menu go to ‘Select’ and hit ‘Invert’.  Fill the inverted selection with black.  Turn the selection off  (‘Select’ > ‘None’).

We are nearly there.  The final step is to make the coastline clean and crisp.  Here’s a quick technique to do this.  In the top menu go to ‘Colors’ and click on ‘Threshold’.  In the pop up menu hit OK.  Now your outline should look like this:

Step 4: Finishing Touches

Now if you are happy with the outline as is you could stop here.  But invariably I find I want to tweak it in various ways.  For instance there are more lakes in this outline than I’d like, and I think even those that I wish to keep could be improved upon a bit.  I’d also like there to be more island chains and some fjords along the northern coast.  So here is where I tend to spend the most time doing finishing touches.  Take a hard round brush and paint white over any lakes which you don’t want, and black over islands that you don’t want. Then zoom in to 200% and, setting the px size of your brush to something suitable for fine detail, paint any islands, archipelagos, fjords or sundry other details you wish to include in the map.  After a bit of work here is what I ended up with: