PDA

View Full Version : Fine Tuning Civil 3D Contours



rdewberry
2008-04-24, 06:35 PM
I'm just starting to get into Civil 3D 2008, and already I'm having an issue with something I'm very used to in Land Desktop. When I have the software create contours for me (for example, laying out a road using a typical section), there are going to be some areas where I'd like to manipulate things manually. In LD, I could set the contours to be polylines and grip-edit, trim and extend them to my heart's content. If there were no problems, I'd leave everything as AEC_contours and go on with life.

Now, in Civil 3D, all the contours are a single entity. If I save the drawing down to 2004 format, the object enablers change them to AEC_contours. If I explode them into polylines, I get PLs with a hideous number of grips.

I work in a small office with only a few seats of Civil 3D, and we haven't done any formal training during this migration. Everyone's kind of wandering in the wilderness making their own discoveries, but all the users agree that this feature/ability is a glaring omission, if it truly has been omitted. We're assuming we haven't found it yet ...

So, the question is this: How can I manually edit contours that Civil 3D created? Thank you all very much for your help.

Harold Pei Jr
2008-04-24, 09:47 PM
Tell your surveyor to get more accurate points.
Other than that, flip TIN lines.

brainman1000
2008-04-25, 03:01 PM
In C3D your contours are just a display feature of your surface. The contours simply display what the surface is. If you don't like the location of the contours then you have to manipulate the surface instead of the contours. As stated above, you can flip faces or edit points, etc.

As for training, I would recommend that you get some kind of formal training in your office. I found it to be an almost necessary step in migration.

rdewberry
2008-04-25, 03:39 PM
Thank you both for your responses. My first thought was to simply provide additional spot elevations to drive the contours where I need them to go. To clarify, these are for design elevations, not modifications to existing, where yes, getting good surveyor data really helps. And yes, we're going to try and get some training, at least for the hard-core users who can then teach the lighter users.

Harold Pei Jr
2008-04-25, 06:58 PM
If you do add points, remember to remove points around that area. Keep only the points that suit what you want. Another thing you could do is use breaklines. I find it a big help, especially if there's a swale that's not being picked up right. Just draw the line you want, go into the surface tab in Prospector, then add breakline. It doesn't always work though, it helps to have your triangles turned on. Breaklines is just a faster way of flipping triangles, but if your breakline has a different elevation as your surface, you could also affect the elevation in that spot.

jpaulsen
2008-04-25, 07:35 PM
Another option is to draw the contours as polylines and add them to the surface as contour data.

I don't recommend exploding the surface because you lose all the dynamic properties between the contours and the surface. But if you insist on doing it this way you can reduce the number of vertices by making sure you are not using smoothing on the surface.

If you need to reduce the number of vertices further use the Map Drawing Cleanup (mapclean) command. Use the simplify objects action and experiment with different values for the tolerance.

brian.hailey933139
2008-04-26, 01:45 PM
Remember, your contours are simply a display of your surface. In LDT, if you modify your contours, and then modify a portion of your surface in a different area, recreate your contours, you lose all your manual editing. Even when I was in LDT, I NEVER manually edited contours for this reason. Add the data to your surface so your contours reflect your surface.

One thing you can do is extract the contour you want from your surface (Surface->Utilities->Extract something or other) and then add that back to your surface as contour data. Now, simply edit that contour and your surface will update. I'm not a big fan of this method.

As others have mentioned, get some training. Civil 3D is definetly not an upgrade to LDT (as I'm sure you've realized). Getting your people trained is almost essential to getting back to (and far above) your current productivity level.

wag24
2008-06-12, 09:00 PM
Anyone know how I go about modeling a retaing wall, that surrounds my building. I tried using the breakline wall command. Inside the wall (between the wall and the building) my grade is raised. Then should grade from the top of the wall to the slab of the building (which I also have set as a breakline but still has grades going through it somehow?). Some grades ignore the wall some adhere to it. Whats going on???? Can't I simply add the 3 retaining wall to my surface as feature lines...then choosed them as wall breaklines, offset inside, choose delta, and enter my values along the wall. Any ideas please!

Harold Pei Jr
2008-06-13, 02:00 AM
What are the parameters that you're putting in for your wall breaklines? How do you have your feature lines set up? Are you putting your feature lines into your surface as breaklines, then changing their elevations?

wag24
2008-06-13, 01:40 PM
1. I took my 3 retaining walls from zero elevation and converted them to feature lines.
2. I assigned those 3 feature lines to my proposed surface.
3. I then went under my proposed surface and added wall breaklines from those 3 feature
lines
a. I choose to offset inside (between the building and the wall).
b. Choose individual points because my wall varies height from 2.5 down to 0 at the
driveways.
c. and followed those steps for all three walls.

Check out this simple expample, my building is 22' in height. Watch what happends when I offset my building as a wall breakline inside 22'. I want the grades to react as if the building is a soild. But everything grades weird.

sinc
2008-06-13, 05:14 PM
It's possible you are running into an issue with the wall breaklines.

Wall breaklines are really two breaklines with a very small difference between them. I have had problems with C3D surfaces if two breaklines are too close together. It's possible that this is what is causing some of your grief.

I can't say for certain, because I have not tried to use Wall breaklines in C3D yet. This is just a possible idea I'm throwing out there, as something to keep in mind...

brian.hailey933139
2008-06-16, 05:50 PM
First thing that comes to mind is that you are assigning the elevation to the breakline instead of a difference. In other words, instead of saying the elevations is 2' lower, you might be saying it is at an elevation of 2'. Can't really tell from your drawing but if you were working in this area (a mile high) you would definitely see it immediately.

dfarris75
2008-06-19, 05:01 PM
I've been told in the past that the vertical products (Land and C3D) tend to have a difficult time with vertical grading. Maybe trying another method would be a good idea.

Also, if you haven't already be sure to view it in 3d (orbit) to give you a better idea of what's happening.

Civil Samurai
2009-04-22, 04:20 PM
I know it's a late response but I agree with Sinc that this is most likely a Wall Breakline issue.

When I'm designing a retaining wall to include in a surface I have feature lines to represent the front and back faces of the wall. Then I will use the Stepped Offset command (Grading->Edit Feature Lines->Stepped Offset) and offset one of them, say the front face, inward at an offset of 0.10' and then the next part of the command allows you to either specify a difference (from the starting line) or you can specify an absolute elevation to the new line. You don't want Feature Lines to get too close to each other, otherwise Civil3D can freak out a bit.

I use this a lot for hillside designs when the client is trying to maximize wall heights. I can take the wall face line on the downhill side and offset it 0.10' in and specify a 10' difference. You can then offset that new line an additional 0.40' (depends on how thick your walls are) and specify a 0' difference. This will give you a flat top of wall which looks half decent on your surface sections. Offset it once again to get the back of wall and you can specify a -0.5' difference to give yourself 6" of freeboard. This technique can then be further used to build your back of wall swales and give you a good toe of slope line to grade upslope with.

Hope this is helpful to somebody. I'd also recommend at least the Civil3D Essentials class. It's a couple days and briefly covers most topics.