Clouds for mapping, part II

I’ve already introduced the idea of using clouds to make maps. So, how do you actually do it?

  1. Step one is to get some photos of clouds, preferably the castellanus variety. They’re nice and puffy, without having flat bottoms. Longer, striated clouds can work, too, but might require some squishing in your image editor to make them resemble natural landforms.
  2. Now, import your photo into an image editing program. I’m going to assume GIMP here, because it’s free, powerful and what I actually use. Other programs will naturally have different steps, but the concepts should apply.
    Image of clouds
  3. Crop the image to a likely-looking section of sky. You want a cloud that has lots of interesting texture, projections, etc.
    Cropped image of clouds
  4. Select the blue areas of the sky using the Select by Color tool. Adjust the threshold to grab more or less sky; the precise amount you’ll need will vary with your image. Also, using different thresholds will give you different coastlines. Imagine your selected area as the ocean — does it look good? Adjust to taste. Play around and try different settings. You may want to feather or expand the selection to grab nearby areas without grabbing all the similar colors, since the clouds themselves may have some areas that are nearly the same color.
  5. Keeping the same selection, create another layer called “oceans” or something. Fill your selection with a nice deep blue suitable for oceans. You may need to use a combination of paint bucket and brush tools here, as the selection will be fuzzy. Just remember to keep the ocean fills on the ocean layer.
    Oceans selected
  6. Go back to the cloud layer and, again using the color select tool, select some portion of the cloud itself — the darker, not-quite-white bits. You’ll want to use a lower threshold on the color select tool here to give more precision to your selections. Again create another layer, then fill the selection with your main terrain color. Here, I’m using a medium green for forest.
    Forest selected
  7. Again go back to your original cloud layer, and select the brighter white areas. (Notice a pattern here?) You’ll again want to use a lower threshold on the color select tool. Create another layer and call it something like “hills”. Choose a nice deep brown, and fill your selection on this layer. Then, once you’re done filling in the hills, lower the opacity of this layer a bit so that some of the forest layer shows through. This’ll make the edges less perfect and more organic.
    Hills selected
  8. And again, go to the cloud layer and select just the brightest bits. These will form your snow- and ice-covered areas. This time, though, instead of creating a new layer, copy the cloud layer and drag it above the hill layer. Create a layer mask equal to your selection. You should now have a nice, small section of snow-covered peaks that already have slightly dappled texture — the texture of your real-world clouds.
    Snow selected
  9. Finally, to add a bit more color variation, create a layer above the forest layer and a layer above the hill layer. Use the spray tool with a big brush that has a random stippled pattern, like (in GIMP 2.8) Chalk 02 or something similar. On the two layers, spray a little bit of black or other dark color. Set the layer opacity low so that the stippling only affects the layers below a little, just enough to break up the color.
    Stippling added

And you’re pretty much done. You’ll probably want to use a higher resolution than I’ve used here (which means high-res cloud photos are probably for the best), and you’ll probably want to add in lots of other details like rivers, towns, roads, and boundaries, but that is (as they say) beyond the scope of this article.

Anyway, I hope this gives you access to natural-looking landforms without having to resort to computer generated fractals and adds a few more tools to your gamers’ toolbox.

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