Missing a non-coplanar ground plane

I need a quick way to create a missing ground plane for this model. I tried a flat plane and it does not meet all the edges of the planters and building walls. So obviously the model was created with survey data, but the ground plane is missing. I do not have access to the original CAD (Revit) file so I just need to create something quick and dirty so that the entry planters that I am working on are not floating in the air.

I made one of my model non-coplanar for test… I made the whole model group, move upward, draw a plane and use “drop by bounds” option of raytracer plugin… All corners meet ground…

That sounds like it would work really well if I knew what the ground plane was and just needed to drop the model onto it. Obviously with sandbox tools there are wats to do that. In this case, I have a model that has all of the floor planes, but the ground plane is obviously missing. If I draw a flat plane and align it with an edge of the building, it does not align at the entry or other locations on the building, and it also buries the peanut shaped planter that is away from the building. I have considered tracing the underside of the building and planters and creating a ground plane using the sandbox tools and those outlines. I’m sure that can be done. But it doesn’t seem very quick and easy.

Is there no existing surface or loop in the model that follows the ground plane you want to make? What are the purple surfaces at the front door?

You can use “C point at vertex” tool of TIG plugin, jhs powerbar plugin has that button also, and topo shaper plugin… Sign C points on the ground level of your model as much as you want, after that points will be already selected, use topo shaper plugin to make ground from point clouds…

Maybe they want you to take care of the landscaping, as well?

As a matter of fact, I was providing quick help for the landscape design firm who wanted to suggest different planter shapes to the architect.

Creating a sandbox surface and deforming by smoove tool of sandbox can fix the problem also…