Incorporating sketchup object with terrain

I was wondering how to combine a terrain model with object geometry using something analogous to the drape tool (think draping a cloth over blocks on a table. The cloth captures both the block forms and the table). I have a terrain and I place a couple of objects in the terrain to represent new landscape geometry. However, the transition between the terrain and geometry is uncouth, and I would like to generate a SECOND terrain/mesh/overlay that captures both the original terrain and placed objects. In essence, the second terrain would function like a drape tool but would recognize the sketchup geometry as terrain.

I have attempted to do this in three different way:

  1. Reverse Stamp Method:

In this method I take the objects and place them under the terrain. Next I use the stamp tool to project the objects up into the terrain. This method works but it is difficult and messy to alter the resulting terrain because of the resulting polygons.

2.Selective contours

This method is the ideal one for me to use… but I am having trouble creating the appropriate contours. In this method, I take a discrete model of the terrain (IE, the contours rise 1’ incrementally by contour, rather than a continuous TIN terrain) and and the sketchup objects and perform the following:
Explode all groups
Intersect faces with model,
Turn on wireframe
Copy-Move all lines
Selectively delete lines such as vertical lines, stacked lines (ie parallel lines when viewed from side)
Attempt to create a new terrain based on those lines which now include the sketchup objects.

As you can see, the difficulty in this is selecting the correct lines to be contours for the model. Attached are three pictures of models, and they are fairly close to what I want, but for some reason, there are sharp valleys and mountains in the areas that are supposed to be level (the polygonal forms). In addition, parts of the terrain that are supposed to be shear drops are angled slightly. This is my prime frustration, and if I could solve how to pick the contour lines correctly, I’d be golden. I prefer this method the most because it would result in clean terrain models that should how the terrain gently transitions into the new landscape geometry.

*(also I realize now that I can take the original contour lines I used to create the discrete mode and place the sketchup objects’ lines there. I’ll try this method out and reply back).

  1. Using a Mesh
    Last but not least is the mesh method. It’s similar to #2, but instead of trying to select the contours, I use a mesh to drape over the terrain and sketchup objects after exploding and intersecting faces.

The final goal of this project is to use each model’s data and allow a CNC router to carve out the topography in a block of wood.
I’ll upload the models as needed since new users can only have one attachment
*quick note about the model: first file is of the Selective Contours Method. The second file has the Reverse Stamp and Mesh methods.

.Selective contours.skp (2.2 MB)

mesh&stamp.skp (2.9 MB)