One of the new features added to Civil 3D 2013 is the ability to select surface and use it as a boundary for other overlapping surface. This one is not easy to explain so I will use one of the possible workflows to describe where you will most likely end up using it. At the same time we can review the workflow about adding boundaries. Two birds with the same stone, kind of a deal. Pay attention on step 4 but let’s go one step at the time.
Here is the scenario: When we created a corridor surface and tied it with Existing ground (EG) surface we often want to see how it all ties together. DRIVE command is very useful tool here because it shows us how the road looks and it looks pretty on the screen. But if we invoke DRIVE command we may see that there are some bumps along the road. These bumps are basically showing those cut areas from our Existing Ground (EG), so the corridor will be obscured here. The gray thing that looks like gray cloud is basically my quick rendering of Existing surface. It looks like the road will get into EG-not good!
You may choose to hide EG, and that’s OK- you can see the entire corridor, but you will not be able to see where it ties into Existing Ground. See how and what after the jump.
To solve this problem we can use the surface boundary to hide the areas which corridor covers. The problem with this approach is that corridor and corridor surface both target the same Existing Surface, and cannot use one another as a boundary, so we have to do something about it. We need to create another surface by pasting EG into it and then applying boundary that we can get out of corridor surface.
1. Hide EG by either applying the style which will hide it or using Isolate option
2. Create new blank surface and go into Edit Definitions, chose Paste
3. In Select Surface to Paste dialog select EG surface
This is a new feature I was talking about in the beginning of this post. Look at the command prompt. Now type S for Surface or just select it
Note: When defining a boundary from a polygon, if the polygon is not closed, the boundary definition forces a closed polygon.
5. Program will create boundary around corridor surface. You should end up with something like this:
Type DRIVE command select your alignment, Feature line or whatever you would like to run your DRIVE command on and play it. You should be able to see how surfaces tie to each other.
Still not pretty, mostly because of my being lazy to do a final touch up, but much better than before. But you get the point! Stay tuned for more!