AutoCAD Civil 3D General Discussion

AutoCAD Civil 3D General Discussion

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TRogers
Posts: 1,310
Registered: ‎09-05-2007
Message 1 of 14 (642 Views)
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Detention Pond Contours Not Correct

642 Views, 13 Replies
12-11-2012 12:38 PM

I have 2 feature lines, one is at elevation 132 (TOB), and the other at 123 (TOE).  I inserted elevation points at an increment of every 3 ft., which should make a smooth arc of contours around the pond.  Not the case.  How do I fix the issue I am having?  See pic below...

 

4-4-2012 8-46-10 AM.png 

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Todd Rogers

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LisaPohlmeyer
Posts: 557
Registered: ‎01-14-2009
Message 2 of 14 (633 Views)

Re: Detention Pond Contours Not Correct

12-11-2012 01:07 PM in reply to: TRogers

Is your surface set to use a maximum triangle length?

Lisa Pohlmeyer

C3D 2012 SP4, C3D 2015
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sboon
Posts: 2,085
Registered: ‎11-08-2005
Message 3 of 14 (628 Views)

Re: Detention Pond Contours Not Correct

12-11-2012 01:15 PM in reply to: TRogers

Switch your surface style to display the TIN lines.  The rules of Delauney triangulation generally force the surface to connect surface points to their nearest neighbours, so in this case you likely have lines running across the inside of your curves, instead of from the inside to the outside featureline.

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TRogers
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Message 4 of 14 (623 Views)

Re: Detention Pond Contours Not Correct

12-11-2012 01:19 PM in reply to: sboon

4-4-2012 8-46-10 AM.png

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Todd Rogers

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jmayo
Posts: 2,796
Registered: ‎11-13-2006
Message 5 of 14 (617 Views)

Re: Detention Pond Contours Not Correct

12-11-2012 01:34 PM in reply to: TRogers

The quick way to fix this is to add them to the surface definition as contours making sure to minimize the flat areas. If you add them as breaklines you will be flippin' all those edges.

John Mayo, PE
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jmayo
Posts: 2,796
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Message 6 of 14 (616 Views)

Re: Detention Pond Contours Not Correct

12-11-2012 01:36 PM in reply to: jmayo

... you will have fewer triangles to flip and a better performing surface if you remove all those elev points.

John Mayo, PE
IDSP 2014
Win 7 64, Xeon ES165@3.2Ghz,
64 GB RAM, Quadro K4000 (x2)
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TRogers
Posts: 1,310
Registered: ‎09-05-2007
Message 7 of 14 (612 Views)

Re: Detention Pond Contours Not Correct

12-11-2012 01:41 PM in reply to: jmayo

It's not allowing me to add the feature lines as contours...

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jmayo
Posts: 2,796
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Message 8 of 14 (602 Views)

Re: Detention Pond Contours Not Correct

12-11-2012 01:52 PM in reply to: TRogers

Oh that's a bit of a bummer. I do use simple plines for basin & bld pad surfaces quite often. Not the greatest solution but if the basin was disconnected from the rest of the design it may not be a big deal losing the dynamic capabilities.

 

The other option is flipping the edges. In both cases I would remove the elv pnts.

John Mayo, PE
IDSP 2014
Win 7 64, Xeon ES165@3.2Ghz,
64 GB RAM, Quadro K4000 (x2)
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jmayo
Posts: 2,796
Registered: ‎11-13-2006
Message 9 of 14 (597 Views)

Re: Detention Pond Contours Not Correct

12-11-2012 01:55 PM in reply to: TRogers

A grading (I don't like these) or corridor are other options but it does not look like the top and bottom outer curves have the same radius as the offset. The lack of symmetry makes these options tough.

John Mayo, PE
IDSP 2014
Win 7 64, Xeon ES165@3.2Ghz,
64 GB RAM, Quadro K4000 (x2)
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TRogers
Posts: 1,310
Registered: ‎09-05-2007
Message 10 of 14 (596 Views)

Re: Detention Pond Contours Not Correct

12-11-2012 01:56 PM in reply to: jmayo

I did remove the elevation points.  I exploded the feature lines and added the poly's as contours.  MUCH more control this way.  I will have to remember this workaround.  Thanks for the info!!

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