AutoCAD Civil 3D General

*Expert Elite*
Posts: 2,519
Registered: ‎05-21-2008
Message 11 of 15 (242 Views)

Re: Triangulation Issues

04-05-2013 11:35 AM in reply to: francisco_bobadilla

I fail to see what is 'wrong' with the TIN.  Sure it looks a bit funky, but that's only natural when you have one point on the left that is triangulating to a hundred on the right.  Maybe if you'd used a larger mid-ordinate distance on the curved breakline it would look a bit nicer.  To me it looks very sparse for data; I feel you need to add information in the middle somewhere to tell the surface what to do.  That applies just as much to the 'good' area of your surface as it does to the 'bad' area.

Or perhaps you can elaborate on what is 'wrong' with the triangulation, so I can understand what you're aiming for?

Credit where credit is due! Give kudos or accept as solution whenever you can.

Posts: 152
Registered: ‎11-09-2010
Message 12 of 15 (226 Views)

Re: Triangulation Issues

04-05-2013 02:09 PM in reply to: troma

You can see the contours get tighter at some spots.  This is not correct.  I will try the mid-ordinate distance setting

Distinguished Contributor
Posts: 125
Registered: ‎12-23-2008
Message 13 of 15 (215 Views)

Re: Triangulation Issues

04-05-2013 04:17 PM in reply to: francisco_bobadilla

Looks like there are points that are not in the surface and no fault lines. 



Surveyor Lee

Posts: 152
Registered: ‎11-09-2010
Message 14 of 15 (200 Views)

Re: Triangulation Issues

04-05-2013 09:58 PM in reply to: SurveyorLee

What do you mean by fault lines?

Valued Mentor
Posts: 1,086
Registered: ‎01-07-2011
Message 15 of 15 (193 Views)

Re: Triangulation Issues

04-06-2013 08:28 AM in reply to: francisco_bobadilla

Yes, start Swapping Edges...


The more experienced and accomplished you become at reading and interpreting the triangulation of TIN surfaces, you will find that you will have the ability to create surfaces solely from point data.


From the C3D Help:


"...Given a set of data points, Delaunay triangulation produces a set of lines connecting each point to its natural neighbors."


It's true! For the most part you can create roads, channels, ditches and even walls solely from points.The surface algorithm in Civil 3D will create the surface per the algorithm . The onus is on the author of the surface to ensure the surface is a correct interpretation per the given data. I'm not advising abandoning the use of breaklines, it is good practice to use Breaklines, however the more experienced you become, you will develop the skill set to be able to quickly visually scan the triangulation of a surface, and note perhaps a few areas where the triangulation needs to be adjusted.


Experienced surveyors have to do this all the time. Before they deliver their final product to us, which is the Existing Surface, they have to finalize the surface  triangulation per how they observed and interpreted the surface in the field, and how they want to portray and deliver that finalized surface as their product to the world. Sometimes, we see mistakes in the triangulation of these final existing surface products, that need to be corrected, such as areas at culvert headwalls, ditch flowlines and banks, retaining walls.


So now with this information and background, you can edit and correct your surface as you see fit by adjusting the triangulation.


You say this is mish mash of pasted surfaces, etc.... You may want to review that definition process on this surface, just to see if it really is making sense and good progress towards you final goal.




Fred Ernst, PE
C3D 2015
Ernst Engineering

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