This is a follow-up to my earlier post on Removing Inland Seas. See that post for details on the settings that will be used here.

The process for flattening mountains is nearly identical to that used to remove inland seas. We are simply lowering terrain instead of raising it.

We will start off with the final stage from the previous tutorial:

If you look closely, you will notice that it isn’t quite the same as where we left off. I neglected to save my changes after removing the lakes and inland seas, so I had to reproduce it. There are minor differences, but essentially it is the same.

Zoom in to the mountain range in the upper right portion. Be sure to select the settings as described in the previous post. Click on Lower Prescale Offset. Set the brush to a height and width of 257 and a value of 0.15 (or thereabouts).

I’ll start by running along the peaks. This is purely arbitrary. The only thing that really matters here is that you move around randomly. If you repeatedly lower (or raise) terrain in the same place, it will be noticeable and look unnatural. Keep in mind that the brush has a feathering effect as it approaches the edges. That helps blur the modifications in order to reduce artifacts.

Here is the same view after just 40 clicks.

And here is what I have after considerably more (I forgot to count, but it was on the order of another 200 I think).

You will notice that a few lakes have started to appear. That is expected and easy to fix. Click on Raise Prescale Offset (on the Editing Toolbar), select the same settings (257 height and width, with a value on the order of 0.15), and raise the terrain centered on each lake.

Note that it is possible to use a finer brush (lower the value to 0.05 for instance) to gain more control and generate more uniform terrain. Unfortunately, that creates more uniform terrain. That is to say that the land will look less random and less realistic. Right now, I think it is important to use broad strokes. When the continents are all the shape you want, and the mountains and lakes fit your general requirements, then you can come back and do some fine tuning. But, in my experience, it is best to approach planetscaping as a sculptor approaches a lump of clay. Form the general shape and gradually work it into whatever form you want, focusing first on gross details, followed by finer and finer details as you go.

Zoom out, find a new area, and repeat. Here is my final product.

You will notice that I wasn’t particularly careful to maintain the coastlines. This is especially evident around the small islands with steep terrain. Flatting the hills there can sink the entire island. The best approach in such situations is to lower in one place and raise in another where the two actions overlap in such a way that the raise avoids the spot where the terrain was highest and includes the lower areas.

That technique can be useful in any type of editing. Remember that the brush is feathered more the closer it is to the edge and use that to your advantage. For instance, when flattening a mountain produces lakes, instead of raising the terrain centered on the lake, center the brush on low terrain around the lake, with the edge of the brush covering the lake section. You can do this in a number of points around the lake, with each click only raising the lake a small amount since it is at the edge of the brush.

Don’t be concerned that a completely flattened continent (as the one above) may look a little odd. If you intend to leave it flat, you will want to come back and do some fine tuning. More likely, you will be adding back in some mountain ranges in more suitable locations, with hilly terrain spreading out from there. Once those features are in place, the land mass will look much more realistic.