Wicked Cool Stuff
Dominick Gallegos, Civil 3D Technical Marketing Manager for Autodesk, shares his unique perspective and ideas on the functionality and use of Civil 3D for a range of different project types.
About DOMINICKLatest Post
- posted 08/17/07 by DOMINICK GALLEGOS Editing a Surface. . . from a Cross Section View
- Many times, we create Corridor models and the top surfaces look amazing. I know when I used to do it using 3D Polylines or even Templates, I would end up with a vertices that were at 0 elevation or just messed up from either my fat fingers or just dumb luck. As most of us know Civil 3D allows us to create top surfaces very easily with a few clicks but what about those complex intersections or funny contours that go astray even though you know your model is correct. Well boys and girls there is a wonderful answer to these types of problems. In the image below, I have introduced a left hand turn lane and we should be seeing two separate contours instead of one that wraps onto the island. In this type of situation a lot of users don't realize that instead of altering the triangles in plan view we can force the top surface to follow our true design intent from a Cross Section View. . . . yes a Cross Section View. When the View/Edit Corridor Section command was introduced, it was a basic viewer so that a user could see what their cross section looked like without having to create cross section but it has evolved into a full-blown editor.
As we dig deeper into this little gem of a tool you can see in cross section view the median has ended but the contour has not tapered down to be completely flat, yet. However, by simply drawing a standard Polyline while you are in the View/Edit Corridor Section command we have essentially created a breakline, in Cross Section View.
Which means we can quickly add this simple polyline to the top surface as a Standard breakline and tada. . . .
. . . . when we switch back to plan view (or even if you stay in Cross Section View) we now have a great looking surface that truly looks as it should and if you look closely you can see the polyline that was created on the edge of the curb and gutter for the median.
Keep in mind that since this works for polylines. . . . try using Points also. Who would have ever thought we can truly edit a surface from a Cross Section View, imagine the possibilities. By the way. . . . I know someone is going to ask. . . no it will not update if the Corridor changes in Elevation but it was easy enough to do the first time, which means it will be even easier to do the second.
User Comments
FYI: Here are precautionary warnings & clarifications from Autodesk Support (Adam Koerner) about this very tutorial:
[quoted from September 17, 2007]:
"… Even if the software allows you to edit corridor sections in this way, I wouldn't do it.
I understand that one of our webcasts may have shown someone inserting a drawing containing a corridor into another drawing and then sampling the corridor for sections in the current drawing... while you may be able to get this to partially work (and I emphasize partially), I do not recommend this practice. I think the presenter just happened upon something that looked like it would work, but it is something that to the best of my knowledge the software wasn't really designed to do. I think this process will most likely end up causing you grief down the road (I can think of one case in particular where the sampled data kept disappearing when this method was utilized).
The rule I follow for sections is that the sample lines and section views belong in the same drawing as the corridor model. Likewise, you should only edit corridor data within the drawing in which the corridor is defined.
Also, a few more bits of unsolicited advice: you cannot edit a corridor surface from a section view. you can, however, edit an inserted assembly in the corridor model in the view/edit corridor sections command. by editing the underlying data, the corridor surface is affected, however, the corridor surface itself has not actually been edited. For what it's worth, I do not recommend editing a corridor surface in any way other than those presented in the corridor properties dialog (no deleting lines, etc). you can add corridor data, add boundaries, etc, but that's it. If you need to swap lines, add additional data that is not sourced from the corridor model, etc, you should create a new surface and paste in the corridor surface. This new surface can then be modified as desired without changing the actual corridor surface. The same procedure applies to grading (and is perhaps more critical there for preserving data integrity/preventing data corruption)."
[quoted from September 18, 2007]:
“… I can tell you that I HAVE seen problems as a result of this process and I would NOT do it, regardless of the existence of some tutorial that says something to the contrary.
In the view/edit sections command, you do not edit surfaces (granted, you do have several basic modify tools available such as erase and move that will work on surfaces). what you do in this command is modify your corridor design data that is used to define the corridor surface...in other words, the surface is defined from assembly links, and in this command you can modify the assemblies/subassemblies that contain these links. You can also manually add points/links into the assembly without requiring the addition of a new subassembly. What you are doing here is modifying the data used to define the surface. this is not the same thing as actually editing a surface.
Please note that I did NOT suggest creating detached surfaces for editing. I suggested creating a new surface that you paste the original dynamic surface into. this is very different from a detached surface. While a bit unorthodox, this method offers several significant advantages, including:
1) keeps the original dynamic surface defined from the corridor or grading data pristine.
2) if you are ultimately pasting the corridor or grading surface into another, the additional surface serves as a buffer. let's consider that you create a merged surface that consists of pasting the existing ground and several design surfaces in a particular order. You then realize that one of the design surfaces must be deleted and rebuilt (for any plausible reason you like). if you do not have a buffer surface, once you delete the original, recreate it and re-paste it into the final surface, the paste order will now be incorrect. There is currently no way to modify the order of edits to a surface, to in order to make the surface right, you would have to remove all edits past the point where you need to put the modified data and then redo the other edits. With the buffer surface pasted into the final design, even if you delete the source surface, the buffer will remain and will remain pasted into the final in the proper order (the buffer will just be empty at this point). you can then rebuild the source data and paste back into the buffer again...at this point the design will be updated with a minimal amount of work. this is a method I have developed based on experience and it works quite nicely.
3) I have seen issues in the past where edits made directly to a grading and/or corridor surface has caused some strange data corruption issues. the same problems did not occur when the corridor or grading surface was pasted into a new surface first (and the new surface was edited).
Best Regards,
Adam Koerner
Autodesk Support Team”
Posted 9/18/2007 4:35 PM by Eldon Bach