I just say one of my competitor's CC model. It was nicely trimmed according to an irregular shape of the site.
Does anyone know how to do it?
Yes, from CC Editor you can draw a shape using Place Smartline or place shape, just make sure you close it on itself.
What would be the simplest way to create a KML or DGN clip shape? In CC editor using drawing tools?
whoooho! I like that! I ask for a feature and here it comes.
Amazing
While this was not possible at the time you asked it, the very recently released ContextCapture Update 9 allows importing a KML or DGN clip shape to apply to a specific production, and the resulting models are neatly trimmed according to the submitted shape. Hopefully it will make the current process a little smoother for that use case!
Best I know is to export the mesh (OBJ) .. edit .. bring it back in .. each and every tile.
I have passed on, internally through my support contact, a feature request, to add a boundary feature via KML or similar, such that the mesh builds up to the boundary ..
If there is another way - would love to hear it!