AutoCAD Civil 3D General Discussion

AutoCAD Civil 3D General Discussion

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david.dixon
Posts: 74
Registered: ‎11-13-2006
Message 1 of 15 (1,357 Views)

I hate squiggly contours!

1357 Views, 14 Replies
06-03-2011 07:50 AM

just venting my frustration with the contour generating engine that Autodesk provides.  And I know you can apply smoothing but that doesn't smooth contours perfectly.  I really liked the engine and algorithm that the Eagle Point civil software had.  EP surface module would produce some very nice sweet contours.

 

Squiggles.png

David Dixon
Senior Civil Designer

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OMCUSNR
Posts: 506
Registered: ‎04-28-2010
Message 2 of 15 (1,354 Views)

Re: I hate squiggly contours!

06-03-2011 07:56 AM in reply to: david.dixon

To borrow a borrowed phrase, "All contours are lies".

 

So it looks to me like you have something going on with the TIN surface that needs editing.  Set your surface view to show the TIN & points, this will help you edit the surface.

 

Try posting a dwg with the surface & we can take a look at it.

 

Reid

Homebuilt box: I5-2500k, MSI P67A-GD65, 12gig DDR3 1600 ram, ASUS ENGTX460 Video card, WD Velociraptor WD4500HLHX HD, Win 7 64 pro.
Valued Contributor
david.dixon
Posts: 74
Registered: ‎11-13-2006
Message 3 of 15 (1,350 Views)

Re: I hate squiggly contours!

06-03-2011 08:06 AM in reply to: OMCUSNR

I cannot post the TIN file since it is a sensitive project for our client.  I understand I have more surface messaging to do.

 

"All Contours are lies" .... funny saying that I see before but I believe it is incorrect.   Contours need to be truthful when you have to have the Contractor excavate out a sediment basin to the exact specifications of your stormwater design so that the system works.

David Dixon
Senior Civil Designer

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SethHall
Posts: 723
Registered: ‎02-08-2010
Message 4 of 15 (1,347 Views)

Re: I hate squiggly contours!

06-03-2011 08:10 AM in reply to: david.dixon

Hi David-

 

Have a look at this blog post: http://beingcivil.typepad.com/my_weblog/2010/04/my-surface-has-waves.html

 

Hope it helps!



Seth Hall
Product Support
GCSO - CSS - FTS
Autodesk, Inc.


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Distinguished Mentor
Civil3DReminders
Posts: 910
Registered: ‎03-24-2009
Message 5 of 15 (1,279 Views)

Re: I hate squiggly contours!

06-03-2011 11:03 PM in reply to: david.dixon

But aren't you asking for the program to create the lying contours through smoothing? Won't the smoothing add information to the surface to create the smoothing which may or may not meet the design intent? It seems to me we get the truth and then decide it needs to be made a lie to make the presentation a certain way.

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wfberry
Posts: 1,936
Registered: ‎09-05-2006
Message 6 of 15 (1,268 Views)

Re: I hate squiggly contours!

06-04-2011 06:05 AM in reply to: Civil3DReminders

Christopher:

 

Any contour line that is some distance from an actual shot point is going to be "non-perfect" so why not have it as "perty" as possible without some exaggeration.

 

Bill

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KirkNoonan
Posts: 456
Registered: ‎09-23-2008
Message 7 of 15 (1,266 Views)

Re: I hate squiggly contours!

06-04-2011 06:17 AM in reply to: david.dixon

I think a lot depends on how you generate your contours. I have very few problems with contours for proposed surfaces in retention areas, pads, etc. where the surface is created through grading or feature lines. Things are usually problematic when generating existing surfaces from a grid of topo points or someone else's contours. Try using linear features as much as possible when creating the surface, and experiment with the optimization tool that are offered (minimize flat areas, max triangle length, etc.) With some practice, some well-placed point addition, and a lot of face flipping or edge swapping or whatever it is called this year, you'll get be able to whip out a decent-looking surface in no time.

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Civil3DReminders
Posts: 910
Registered: ‎03-24-2009
Message 8 of 15 (1,258 Views)

Re: I hate squiggly contours!

06-04-2011 08:47 AM in reply to: wfberry

I agree that the contours for the most part should be perty, but I don't think as an industry we should be spending the amount of time and energy on smoothing contours as we do. 

 

From an economic standpoint it saves money and makes a firm more profitable. For instance I was working on a project that transitioned from the top of a designed slope to existing ground a non uniform distance from the wall. With each design iteration we did the other engineer wanted the contours to be smooth. I spent 2 to 3 hours for each iteration to smooth contours and we did 4 to 5 iterations for one submittal. So that's about 15 hours of work wasted on making the contours perty for just one submittal. Did it make the design better? Did it make the project easier to build? Both answers would have to be no. I think the better answer would be to educate others that the smooth contours won't make the design better. The contractor is in reality going to build the squiggly contours. The surveyor is going to stake out the project from a line and then the grade checker is going to set temporary stakes perpendicular to the line down the slope to the top of the wall. If we connect those points after the project is built we should get the some squiggly contours, they will not be smooth like the plan shows. Essentially I was taking how the project was going to be constructed and then making up lies to get the contours to be smooth. Actually for the smoothing I was doing I'd feel sorry for the surveyor and grade checker if they actually had to build to the contours. They'd probably need a ten foot stake to fit all of the slope change information in some spots on the slope. 

 

Since being green is fashionable today, there's the energy expended on making the changes. I could have reduced the carbon footprint of the project by not doing the contour smoothing. Think of the tons and tons of carbon we collectively could reduce if we didn't spend needless time smoothing contours.

 

Then there's also the technological advancements since the idea of using contours to show the design intent. If we want accuracy we need to provide the contractor with a digital model for use in a GPS system to grade the site. That way the blade of the dozer or grader knows exactly where it should be as it traverses the site. The technology is there it's just the adoption which is lagging.

 

Mathmatically and engineering wise the squiggly contours are correct. They follow the rules of TIN creation and what information the designer has provided, therefore it represents the design intent. Once the contours are smoothed we start creating the lies the original poster indicated he doesn't want.

 

There are ways to reduce the squiggly contours:

  • Using supplementing factors that are smaller than 100 and 1 when adding breaklines.
  • Extracting a surface from gradings and then pasting them into the design surface, instead of exploding grading objects to get breaklines to add to the surface.
  • Sequestering curves in parking lots with tangent lines of the curves. The tangent lines would reflect the slopes of the pavement in front of the curves.
  • Avoiding the use of varies slopes and go with uniform slopes.
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Joe-Bouza
Posts: 5,187
Registered: ‎12-15-2008
Message 9 of 15 (1,247 Views)

Re: I hate squiggly contours!

06-04-2011 04:47 PM in reply to: david.dixon

Well if those contours are so truthful then we can provide coordinate on them for the contractor shouldn't we? I have yet to see an as-built survey that shows the exact elevations on the design plans. There's argument number 1, designers flipping faces ... Number 2, .... Surveyors that massage contours "to make them look good" before you even get them that's number 3. People that use Google Earth (wow) number 4, and the list goes on and on.

 

Contours are not exactitude they are a representation. And yes it is nice when they look nice.

Thank you

Joseph D. Bouza, P.E. (one of 'THOSE' People) Civil 3D 2012 & 2013
HP Z210 Workstation
Intel Xeon CPU E31240 @ 3.30 Hz
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Joe-Bouza
Posts: 5,187
Registered: ‎12-15-2008
Message 10 of 15 (1,246 Views)

Re: I hate squiggly contours!

06-04-2011 04:49 PM in reply to: Civil3DReminders

Thank you. Number 5.......:smileywink:

Thank you

Joseph D. Bouza, P.E. (one of 'THOSE' People) Civil 3D 2012 & 2013
HP Z210 Workstation
Intel Xeon CPU E31240 @ 3.30 Hz
12 GB Ram


Note: Its all Resistentialism, so keep calm and carry on

64 Bit Win7 OS
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