Hello. I will try and explain this best I can. I am trying to combine 2 overlapping surfaces in TBC. Using the TBC or RPS Combine Surface command, while it does result in the surfaces being combined with the later surface overwriting the first selected surface. The issue it that the command appears to trim out intersecting triangles and re-tin. If there is a large vertical difference (or mesh vertices spacing is large) between surfaces I get a undesirable result. Is there any workflow that would allow me to specify a buffer(say 1’ or so) that would clip the first surface, honoring the first surface slope by creating a breakline at the intersection, and repairing the mesh between the two surfaces? Any input for this workflow is appreciated, thank you.
Elijah
the command Combine Surfaces is not designed to merge overlapping surfaces - it is designed to combine multiple isolated island surfaces into a single surface that can be used in a corridor model.
To Merge surfaces you should try the Merge Surfaces command - in that you can decide how the merge function works ie Keep the Highest, Keep the Lowest, Keep the first or keep the second surface in the areas where the two overlap.
In the case in your images - it looks like one surface is large and the second surface is a strip (canal) down the middle - What I would do is merge the Large with the small and keep the small in the merge operation (this creates two equal sized surfaces and them merge the large surface with the merged surface created first and then decide what I want to do - Keep Lowest, Keep Highest in that process
In some combinations the merge surfaces command will create a resulting surface that is the overlapping area only (Keep Highest / Keep Lowest) because a Highest or Lowest only exists where the two surfaces overlap.
To create a buffer zone - I create a surface edge breakline around the surface and then offset the line by 1’ and then drape that line over the other surface and add it to the other surface so that you have a common line that causes the desired triangulation.
Hope that answers the questions
Alan
Thanks Alan! I misspoke in that I was using the TBC Merge Surfaces Command and not RPS Combine surfaces command. As the smaller surface was both higher and lower then the larger OG surface, I was thinking using the type of merge ‘finish replaces existing’ would be the best selection.
I cannot get the draped line to add to the second surface, perhaps because it was imported via XML, but that looks like a viable solution if I can get it to add. I will keep trying.
The software I am coming from has some nice options for such an occasion. Possibly some additional options in that command would allow the task to be completed in one step.
Thanks again.
Alan, here is a clip of me trying to add the draped line to the lower surface. Perhaps you can let me know the reason that the draped line is not able to be added to the surface? It does work for other linestrings I try, just not the draped line offset from the extracted surface breakline. You see in the end ‘0 objects added to the surface’.
Instead of using Drape (which creates a dependent object, try using the Change Elevation command from Data Prep menu - you may need to change it once to Undefined and then a second time to Surface and select the surface to drape it over. Once you have done that then you can add / remove surface members and add it to the surface that you draped it over using change elevation.
The issue with Drape Line is that it is dependent on the surface so it could be that it would not like a circular reference - i.e. add it to the surface that you draped it over on which it is a dependent object. You can explode a draped line to break the dependency and then you should be OK - but I use Change Elevation command for that every time so that I don’t have to explode it etc. to achieve the same end result.
Sweet!
Great job Elijah
Alan