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Creating Realistic River on Fantasy Maps in GIMP 2.8 (2.10.12)

I've been drawing maps for D&D since first playing the game in '78. Playing online requires digital maps, so I taught myself using GIMP.

Rivers Run Deep

Rivers Run Deep

Rivers Run Deep

I started creating fantasy maps for my Dungeons and Dragons campaign by hand many years ago before computers made it into the home. It was easy to draw rivers with pen and ink and the maps held as much detail as one took the time to put in them. We soon learned less is more in most cases.

Today, with modern computer tools I started making maps again, for my online Dungeons and Dragons campaign. Who knew? Making maps for online requires a different set of tools if you want the detail beyond the pen and paper variety. But creating rivers eluded me. Until I found the secret.

Creating realistic rivers is a chore if you don't have the right tools. Learning how to use those tools is an important part. Using a pressure-sensitive drawing tablet is an easy fix to this problem but I don't have one. I found a solution. I will be using GIMP 2.8 for this tutorial because it is easy to learn and free to download, so anyone can follow along.

Step One: land and sea

Step One: land and sea

Step One: Create the Land and Water Layers

We'll start this tutorial with the land and water layers already made. If you don't know how to do then check out my other articles on creating Fantasy maps. This tutorial is strictly on creating rivers.

  1. Create three layers: one for Water, one Land and the last for a Texture layer.
  2. Use the filters and gradients to create the contours of the land so you can have a reference to draw your rivers.
  3. Open a new layer on top of them all. This will be the layer you draw your rivers on.
Step Two: Creating a Path

Step Two: Creating a Path

Step Two: Create a Path for Rivers

Using the Path tool to create your rivers is better than the paintbrush or the Free Select tool because you can take your time drawing and you can edit the path after the fact if you don't like the result without having to go back to start.

Once you use the path tool to draw a line following the contours like a real river would we can fill in the path with color. Always draw from the mouth of the river to its source.

  1. Click on the Paintbrush and use the Tool Options menu to set the values like the following.
  2. Set the brush size to what you would if you were drawing a river with the brush.
  3. Set the Brush Dynamics to Fade Tapering then click on Dynamic Options.
  4. Check the Reverse check box. This sets the taper of the river from wide to small.
  5. The last thing to change is the fade length. This you'll have to adjust each time depending on the length of the river you have drawn. It is measured in pixels and I set it to about double the length you think the river is.

Once the Tool Options are set you choose the brush color as normal then under the Edit Menu choose Stroke Path. This brings up a Stroke Path selection box.

  1. Choose the Stroke with a paint tool
  2. Select the Paintbrush as the paint tool
  3. Check the box Emulate brush dynamics.

Now you can click on Stroke and it will fill in the path.

Adding the tributaries

Adding the tributaries

Step Three: Add Tributaries

Each river has to be added with a new path, as do the tributaries. Things to watch out for is the terrain dictates the river's width as well as direction.

Adding a tributary along the length poses some challenges. You have to estimate the width of the starting point so it matches the point of entry.

Remember that the river downstream is now carrying the water from both the river and tributary so the tributary can't be wider than the river.

Step Four: Rivers Run Deep

Step Four: Rivers Run Deep

Step Four: Add Depth to the Rivers

Once you have all the rivers and tributaries drawn, you have to add depth to the land. This is done by manipulating the layers.

  1. Move the Rivers layer above the water layer and then select the River layer and merge it down to the water layer.
  2. On the resulting water layer select by color the transparent background.
  3. Invert the selection.
  4. Work on the Land layer next ( with the water area selected)
  5. Use the filter Decor: Add Bevel... (set the thickness to match the scale of your map; for this map, it was set to 15)
  6. Use the same filter again, if the effect is not as pronounced as you wish them to be.

Step Five: Add Finishing Touches

Now the map is done but for highlights. Use the techniques mentioned in previous tutorials to highlight and enhance the contours of the land. Other things to touch up are the junctions of the rivers. The colors may not match if you use gradients to color the water. I use the smudge tool to blend the junctions.

GIMP 2.10.12

GIMP 2.10.12

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.