Mini-Tutorial: Creating a Mountain Lake

The core principle for creating a lake within a terrain is to create a “Max area”. Essentially, you create the desired shape of the lake, and use the Max mode in the Combine node to create the lake both physically and for masking purposes.

Creating a Lake

We start with a simple mountain area created with a Voronoi node. We’ll use the middle cell for creating a lake.

Next, mask out the area you want for the lake. If there are slopes around, don’t try to avoid them because you want to go for maximum coverage. Ensure your Feathering is set to 0, otherwise it may create ugly edges that will be a nightmare to work with later on. You want sharp, crisp edges.

Apply a Clamp to Mask output, and connect it to a Combine node along with the original terrain node (Erosion in this case). We’ll come back to this in a moment.

Set the Combine node to the Max method and set the Ratio to 100%. Right-click the Combine node and select Pin. This will now fix the visual to the Combine node. Now you can go back to the Clamp node and reduce the Maximum point until the lake body (mask) creates a flat, level surface within the sloped region.

Tip: You can adjust the mask as needed by drawing and erasing relevant bits.

The Combine node gives us both the physical terrain with the lake body embedded, but also the Separation mask.

Using a CLUTer node, the lake can be identified more clearly.

Our lake is ready!

Notes

The Separation mask will be very useful along the way as you fine tune and texture the overall terrain. It can also be used (perhaps with Invert) in many situations to keep other modifications on the terrain from affecting the lake body.

There are multiple strategies for dealing with the lake bodies:

• You can create the lakes at the very end of your graph — merging with the terrain and textures using the mask. This is the quickest option and should suffice for most situations.
• You can create the lakes early on as needed but use the Separation mask to avoid further erosion or other modifications from impacting the lake. This is a bit harder, and may not always work because the mask has sharp boundaries.
• You can create the lakes early on, don’t use the mask for avoiding further erosion, etc. but combine the lake body again towards the end of your graph. This is a much cleaner method than the previous one. It is useful when you want to use the lake mask to affect other nodes, but still want a clean surface at the end.