AutoCAD Civil 3D General Discussion

AutoCAD Civil 3D General Discussion

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CADEngr2014
Posts: 150
Registered: ‎06-14-2013
Message 1 of 10 (433 Views)
Accepted Solution

SURFACE TRIANGULATION

433 Views, 9 Replies
02-26-2014 12:15 PM

Hello,

 

I am using Civil 3D 2014.

 

I have recieved existing contours from my surveyor and added them to an existing grade surface, using 5-feet supplementing factor and 0.10 mid ordinate distance, when added as "breaklines".  I have also added them as "contours" without any visible difference.  However, I notice that in a few places, the surface does not appear to triangulate to the contours (see attached image).  It appears this may be a limitation working with contour surface data, perhaps we should be using tinn triangles from surveyour and not contours?  Any suggestions? 

For a great explanation of what I mean, watch this video from AU2013 (from around 8:30 or so for about 4-5 min).  It's talking about taking survey data from C3D to revit.  But the reason I would not want to import contours into C3D is the same.

 

http://au.autodesk.com/au-online/classes-on-demand/class-catalog/2013/revit-for-architects/ci3206

 

These guys do a great job of explaining the issue.

 

EDIT:  If you watch it long enough, you'll see why I say I'd want the breaklines too.

I would decrease the supplementing distance/angle values so that Civil 3D adds points where those triangular shapes are showing up, then it can apply its contour optimization settings because there will be points for it to process.

I would also ask for the triangles in addition to the data currently supplied and use these to build the surface.

I'd also do a quick visual check on how the contours compare with the supplied ones.

Contours would be my last resort when building a surface for the reasons given by doni49

You are probably already all set here, but if you can't get the surveyors C3D surface you want to receive the TIN lines and the borders.

 

In C3D when you create your surface by importing 3D Faces (TIN Triangles from C3D) or importing Lines (the TIN lines from LDD) make sure you have the "Maintain Edges From Objects" checked on.  Otherwise the TIN can retriangulate on you and will not agree with edits the surveyor has made.  Save smoothing, whatever your prefered method, these contours should all agree very closely, and the data between contours, as Doni pointed out, will be correct all the way around.

 

Then you can add any outer and hide borders.

 

LandXML is good, but also has the ability to re-triangulate on you if not exported correctly/completely, no matter what you do on your end to make sure that doesn't happen.

 

 

*Expert Elite*
tcorey
Posts: 2,600
Registered: ‎12-18-2002
Message 2 of 10 (425 Views)

Re: SURFACE TRIANGULATION

02-26-2014 12:31 PM in reply to: CADEngr2014

What flattening options are you using when you add the contours to the surface? That makes a huge difference.

Tim Corey, Owner
Delta Engineering Systems
Redding, CA
Autodesk Authorized Value-Added Reseller
*Expert Elite*
doni49
Posts: 1,659
Registered: ‎12-22-2012
Message 3 of 10 (423 Views)

Re: SURFACE TRIANGULATION

02-26-2014 12:46 PM in reply to: CADEngr2014

Would your surveyor be willing to provide you with triangles?  (A C3D surface would be the best but take what you can get)

Don Ireland



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CADEngr2014
Posts: 150
Registered: ‎06-14-2013
Message 4 of 10 (410 Views)

Re: SURFACE TRIANGULATION

02-26-2014 01:25 PM in reply to: doni49

I believe the surveyor will provide what is requested for the most part.  I just need to confirm what is the best data to request.  Would triangles trump contours?  How about LandXML, is that even better?

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doni49
Posts: 1,659
Registered: ‎12-22-2012
Message 5 of 10 (404 Views)

Re: SURFACE TRIANGULATION

02-26-2014 01:32 PM in reply to: CADEngr2014

The best would be the dwg file with the surface in it then Points & Breaklines, then triangles.  Then somewhere down the list would be contours.

 

Contours are an interpolation of the triangles.

 

Think of it like getting data from someone and they've rounded everything to 1 decimal place and you want to add their data to yours which is accurate to 4 decimal places.  Their data is rounded off (interpolated).

Don Ireland



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doni49
Posts: 1,659
Registered: ‎12-22-2012
Message 6 of 10 (403 Views)

Re: SURFACE TRIANGULATION

02-26-2014 01:40 PM in reply to: doni49

For a great explanation of what I mean, watch this video from AU2013 (from around 8:30 or so for about 4-5 min).  It's talking about taking survey data from C3D to revit.  But the reason I would not want to import contours into C3D is the same.

 

http://au.autodesk.com/au-online/classes-on-demand/class-catalog/2013/revit-for-architects/ci3206

 

These guys do a great job of explaining the issue.

 

EDIT:  If you watch it long enough, you'll see why I say I'd want the breaklines too.

Don Ireland



If a reply solves your issue, please remember to click on "Accept as Solution". This will help other users looking to solve a similar issue. Thank you.


Forum links:
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Civil 3D General
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Mentor
CADEngr2014
Posts: 150
Registered: ‎06-14-2013
Message 7 of 10 (362 Views)

Re: SURFACE TRIANGULATION

02-27-2014 02:48 AM in reply to: tcorey

TCorey,

 

I have attached my flattening options, at least the ones I am familiar with.  If they should have different defaults, what should they be set to?

*Expert Elite*
tcorey
Posts: 2,600
Registered: ‎12-18-2002
Message 8 of 10 (326 Views)

Re: SURFACE TRIANGULATION

02-27-2014 09:41 AM in reply to: CADEngr2014

I would decrease the supplementing distance/angle values so that Civil 3D adds points where those triangular shapes are showing up, then it can apply its contour optimization settings because there will be points for it to process.

Tim Corey, Owner
Delta Engineering Systems
Redding, CA
Autodesk Authorized Value-Added Reseller
*Expert Elite*
neilyj
Posts: 3,789
Registered: ‎08-01-2008
Message 9 of 10 (310 Views)

Re: SURFACE TRIANGULATION

02-27-2014 11:43 AM in reply to: CADEngr2014
I would also ask for the triangles in addition to the data currently supplied and use these to build the surface.

I'd also do a quick visual check on how the contours compare with the supplied ones.

Contours would be my last resort when building a surface for the reasons given by doni49
neilyj
(No connection with Autodesk other than using the products in the real world)


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wetsnow13
Posts: 49
Registered: ‎10-16-2012
Message 10 of 10 (263 Views)

Re: SURFACE TRIANGULATION

02-28-2014 06:40 AM in reply to: CADEngr2014

You are probably already all set here, but if you can't get the surveyors C3D surface you want to receive the TIN lines and the borders.

 

In C3D when you create your surface by importing 3D Faces (TIN Triangles from C3D) or importing Lines (the TIN lines from LDD) make sure you have the "Maintain Edges From Objects" checked on.  Otherwise the TIN can retriangulate on you and will not agree with edits the surveyor has made.  Save smoothing, whatever your prefered method, these contours should all agree very closely, and the data between contours, as Doni pointed out, will be correct all the way around.

 

Then you can add any outer and hide borders.

 

LandXML is good, but also has the ability to re-triangulate on you if not exported correctly/completely, no matter what you do on your end to make sure that doesn't happen.

 

 

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