AutoCAD Civil 3D General Discussion

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Message 11 of 16 (185 Views)

Re: C3D 2012 Volumes help

07-06-2012 02:30 AM in reply to: TheJabberwocky
Use mindistbetweensurfaces (I think this is the name not in front of c3d at present)
(No connection with Autodesk other than using the products in the real world)

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Message 12 of 16 (173 Views)

Re: C3D 2012 Volumes help

07-06-2012 03:06 PM in reply to: TheJabberwocky

Using a volume surface the two surfaces being compared meet at elevation zero.  I create a surface style to display major contours only and set the contour increment to a number larger than the volume surface elevation range.  For example, if the maximum volume surface elevation equals +12 and the minimum volume surface elevation equals -14, I set the contour increment to 15.  Only the zero elevation contour will display showing the limits of cut and fill.

Mike Norton - The Civil Guy

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Registered: ‎04-27-2005
Message 13 of 16 (163 Views)

Re: C3D 2012 Volumes help

07-07-2012 05:39 PM in reply to: TheJabberwocky

Sounds like you are calculating a filling curve. The elevation analysis won't work for that because it does the computations in depths, not elevations.


I wrote up one way to calculate a filling curve on my blog. You can read about it here: 

Posts: 17
Registered: ‎05-29-2012
Message 14 of 16 (145 Views)

Re: C3D 2012 Volumes help

07-09-2012 04:35 PM in reply to: mnorton

Thankyou for your responses.


Sorry, but I didnt have to try the 3rd way.


I used the command MINIMUMDISTBETWEENSURFACES to create a line and then double checked it against the 0 contour in my volume and they matched perfectly.

Posts: 17
Registered: ‎05-29-2012
Message 15 of 16 (141 Views)

Re: C3D 2012 Volumes help

07-09-2012 05:44 PM in reply to: TheJabberwocky

I was hoping to get more assistance on these surfaces. Boy its driving me crazy.


I'm a surveyor, not a civil engineer, so I dont normally deal with these kinds of things (the creation of, not use of). But I need to use the DTM to setout the face of the wall. I'm just having a slight issue with it further down. And since we are using roughly 16000 cubic meters of concrete I want to get it right.


Everything is in meters.


The eastern end of the wall has a grade of 0.5h:1v


The western end of the wall has a grade of 0.7h:1v


Theres a roughly 8m gap where it transitions.


My four points surrounding it are


E: -51.44

N: 111.664

RL: 128.281


E: -51.44

N: 91.664

RL: 168.281


E: -59.99

N: 111.568

RL: 136.429


E: -59.99

N: 911.568

RL: 165.00


When I try and create a surface I get either a dip or a hump in it where the triangle comes up, depnding on which direction the triangles run.


How can I smooth this out to create a "flat" surface across there so I can set it out properly on site.

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Message 16 of 16 (131 Views)

Re: C3D 2012 Volumes help

07-09-2012 07:31 PM in reply to: TheJabberwocky

It's the nature of a TIN surface.  The twisted surface shape that you're trying to represent has to be interpolated by the triangles, and it seems that you're not providing enough detail to the surface for it to work as you would like.  I recreated your data but added a series of extra featurelines to improve the interpolation from one side to the other.  It's still not perfect, you can see the wiggles in my contours but hopefully it's enough for your purposes.


If you wanted to improve it further you could add a series of elevation points along each of the N-S feature lines so that the triangles aren't running all the way across the surface.



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