Trouble placing trees onto terrain in rhino

I have trouble placing forest or trees onto the terrain model I created using the “adjust to terrain” command in Lands Design plugin. I created the terrain using patch tool in rhino, and wonder if that’s the reason for it? Is there a way to resolve this?

Hi Bianca,
The Lands terrains are created using the laTerrain command, selecting curves or points as input geometry.
If you have a mesh or a surface you can also tag it as a terrain, which is an option available from the Lands Edit panel. This object won’t behave as a true Lands terrain, and it won’t have the same features but plants located within the boundary of that mesh/surface will be placed on top of it.

Thank you for your reply. I successfully dropped the forest onto the terrain using your method you suggested. However when I started putting single trees onto a “flat plane” above the terrain, using imported reference lines from CAD, and attempt to drop it back down to the “terrain”, it didn’t seem to work. Would you please advice why this is the case? Have I missed a step?

You must instruct Plants to adust themselves to Terrain by using the “Adjust > To terrains” contextual option:

Have you used the Plants from points option? In this case they are not elevated to terrain by default… For the rest of cases the toggle in the Top-Right corner of the Lands Edit Panel is used to determine whether to elevate to terrains newly created Lands objects.

Thanks for your reply. I have clicked on the “Adjust to terrain” option but the single trees I inserted remain on the plane above the terrain. I have snapped the single trees onto 2d blocks imported from CAD on the plane above the terrain…I wonder if that is the problem? The adjust to terrain function works when I chose the forest option and selected a drawn 2d area above the terrain.

What do you mean with snapped? I see a plant directly inserted in the document, elevated to terrain (since the option to don’t adjust it no more appears in the context menu) and staying high. Are you sure there is a Terrain or an object tagged as terrain under the plant? The perspective doesn’t help. Is the green surface tagged as terrain? If so, has it its normals pointing up?

You have two surfaces, one of them with its normals pointing down. Select the smaller central surface and right-click on the following button to invert its normals:

This should fix the problem.

Hi Albert,

The topography is built as a mesh using the “patch” tool and tagged as terrain (Green surface). I have inserted the plants using the lands design plant pallette onto a 2d cad base which is elevated in the air above the terrain. I am hoping that those 3d plants will drop down to the right levels on the terrain.

Sorry I don’t quite understand how inverting the surface would help solve the issue?

Yes, that’s because, when elevating objects to terrains, Lands Design will not take into account those faces which normal points down. So, the result is like if your surface wasn’t there.
Normals should point to the exterior side of the object, where other objects can be placed without collide, in your case the positive Z. At least this is how Lands is interpreting them.

Hope this help. Anyway you just need to right-click on the normal’s button after selecting the tagged mesh to check if it works.