How to create a water body or a lake on a terrain?

The easiest and simplest way to simulate water on a terrain object is by creating a planar surface that intersects with the terrain. If you need the volume, create the water as a volumetric shape and trim it with the terrain. But take into account that Lands Design terrains are meshes stored in a block (a smart block), so the regular Rhino mesh commands don’t work on it directly.

You need to follow these steps:

  1. Extrude the surface used as the water surface and make it as deep as the bottom of the terrain surface.
  2. Make sure you are using a base on the terrain (so it is a closed mesh). You can find a checkbox in the Lands Edit Panel, after selecting the terrain, in case the base wasn’t created.
  3. Make a copy in place of the terrain and explode it. (We recommend hiding the original terrain).
  4. The exploded terrain will be exploded into different meshes and the curves used for the 2D terrain contours. You can select these curves and delete them.
  5. Join the resulting meshes of the exploded terrain with the _Join command. Usually, a terrain is divided into the top mesh and 4 sides meshes, but if you added some cut and fill operation, hole, path, or division, there will be more meshes. We need here to obtain a closed mesh as a result.
  6. Run the _TrimMesh command to trim the extrusion with the mesh of the former terrain.

That’s it. This process can be automated in Grasshopper if you need to change the elevation of the surface and the depth of the water.