SURFACE TRIANGULATION

[CADEngr2014]

Hello,

I am using Civil 3D 2014.

I have a surface with a point group added to it as the only data in the surface.  However, I am finding some of the points are not being included in the triangulation.  See attached image.  The minimum triangle length is not being used and I can not underestand why this would occur.  I have had to use a feature line to pick-up the extra points.  Any ideas why some of the points in the point group will not traingulate in the surface?

[Jay_B]

Are these Points included on the Points List tab within the Point Group used?

Is Exclude elevations less than Elevation < being applied?

[CADEngr2014]

Yes, thank you.  All points are included, and attached are the special settings which do not include anything special as shown in attached image.

[tcorey]

Post your drawing...

[sboon]

Sometimes the triangulation algorithm needs a little help.  Try using the Edit Surface -> Add Point tool to add a random TIN point somewhere outside the location of your cogo point.  If the surface adds both your point and the new TIN point then try deleting it.

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[CADEngr2014]

Drawing is posted.  Presently have a breakline assuming the elevations the points should have.  If you delete the breakline you will see the surface does not triangulate to the points.  I have tried adding "Points" using surface edit tools but no results.

Thanks in advance for any help with this.

[Jay_B]

There are 2 problems I found with your file:

1. The Point Group "Field Borings" used in the Surface definition has Points 102-104 excluded from the group  on the Exclude Tab of Point Group.

   Go to the Point Group in Prospector and notice at bottom of Prospector these Points are absent from the group. (may have to slide the separator up otherwise points might not appear along bottom of Prospector).

2. These three points contain no Z value. See Panorama after I included 102-104 & rebuilt Surface.

[Jay_B]

This may also help, the 3 Points it's not triangulating to all have a blank Z value not even a zero value.

[CADEngr2014]

Yes, your observation is correct.  I should have mentioned, the missing "Z" values are as intended.  There are three points without elevation values and are in a separate point group to exclude them from the surface.  These "Z" values are excluded because the field data was not available.  However, the remaining points should all triangulate.  Instead, I added a brakline to force triangulation to these remaining points.

[Jeff_M · Accepted solution]

This something built into the C3D surface triangulation algorithim, I'm afraid. Probably has something to do with the way it optimizes the points for speed. This has been discussed in the past, with no, good, solution offered other than to add the breaklines as you've done.

http://forums.autodesk.com/t5/AutoCAD-Civil-3D-General/Surface-will-not-recognize-points/m-p/2625589...

[Jay_B]

I see, when I looked at your png in the OP I took it to mean any point not being triangulated to in that picture were also supposed to be included in the Point Group.
Now it's all making sense.