Create Surface

[sbd123]

I want to create a Surface using 3D Polylines (ContourLines). Is it possible in AutoCAD Civil 3D 2012 ? If yes how?

[Alfred.NESWADBA]

Hi,

>> Is it possible in AutoCAD Civil 3D 2012

Yes 😉

>> If yes how?

Create a surface and add the 3DPolylines either as geometry or as breaklines, there for open the tree for the new surface in the projectbrowser and right-click "Breaklines" ==> "Add" and use the "Standard" breakline type then.

Good luck, - alfred -

[antoniovinci]

First, contours are not 3D polylines, but normal 2D plines with elevation on the Z axis.

Second, in the surface definition, instead of adding "Breaklines" (as written by mein freund Alfred), you have to add "Contours".

[Alfred.NESWADBA]

Hi,

for the triangulation it does not make a difference to add the 3D-polys as contours or as breaklines, except two additions:

It will make a difference withinin the options for cleaning options or options for point-additioning. So adding of contours and adding of breaklines are handled differently.

It may also make a difference when afterwards adding breaklines and therefor getting crossing breaklines.

Anyway, if there are 3DPoly's I always use the breaklines-option out of two reasons:

• if anyone modifies afterwards the 3dpoly (stretching vertices in z-direction) the meaning of "contour" is wrong then and it may happen that someone get's irritated when looking to the project some years later.
• 3D-polys don't have arcs, so all the (slowing) options for segmenting ... are not of any interest, so adding breaklines is the faster way to get geometry added to the surface.

At least ... both options will work, and everyone has different practices of how to do. 😉

- alfred -

[neilyj666]

It could be the case that the data was derived via third party software which may indeed have output the contours as 3D polylines

[Neilw_05]

There is a significant difference between adding polylines as breaklines vs. adding them as contours. The difference is the Minimize Flat Triangles option works best on elements added as contours. Thus if your polylines are truly contours (all vertices at one elevation) then you will likely benefit from the minimize flat triangles option so you will want to add them as contours, not breaklines.

See the help file for an explanation of the Minimize Flat Triangles option when adding contour data to a surface.

[BrianHailey]

As far as I know, the only different between adding the lines as contours and adding them as breaklines lies in the dialog box options. When you add them as breaklines, you can choose to weed and suplement the lines. If you add them as contours, you don't get the option to do it or not, it will do it.

Also, when adding them as contours, you are immediately offered the option to minimize flat areas. If you add them as breaklines, you would have to add in the minimize flat areas edit yourself.

If I were adding multiple areas of contours to a surface, personally I would add them as breaklines so I don't get several minimize flat areas edits added to my surface. 

As for the minimize flat areas settings, here is my take on how they should be done: 

http://civil3dplus.wordpress.com/2011/08/13/adding-contours-to-a-surface-youre-doing-it-wrong/

[sbd123]

Thanks everyone.

[Neilw_05]

Brian,

Are you sure the Minimize Triangle algorithms are applied to breaklines? The help file seems to imply they only apply to contours. If they are indeed applied to breaklines it would create problems with planar objects such as building pads. I would find that problematic.

[BrianHailey]

The minimize flat areas doesn't work on contours or breaklines, it works on the surface. If the surface has flat areas, the minimize flat areas routine will minimize them.

Try it yourself (I just did). Create a surface from contours. Create a surface from contours but add them as breaklines and use the exact same weeding and suplementing factors. Then add a minimize flat areas edit to the breakline surface using the exact same settings as you did when you added contours. Do a volume comparison and you'll see a cut of 0 and a fill of 0 indicating they are exactly the same.

In other words, there is no difference between adding contours and adding breaklines other than adding contours requires weeding and suplementing factors and immediately allows you to add the minimize flat areas edit.

[Neilw_05]

It's good to have confimation from your tests Brian. The help file is a bit confusing on the matter. I'm posting a clip showing what it says.

The highlights show that the Minimize option affects both breakline and contour data but then the help file seems to imply that the minimize option has unique affects on contour data.

[JeffPaulsen]

As expected Brian is correct. I guess I never saw minimize flat triangles work on breaklines because my breaklines are never flat.

I still prefer to define contours as contour data just to keep things a little more organized. I usually turn off the minimize triangles when I define contour data. After defining all the data I put one minimize triangles into the definition manually via surface edits.

[BrianHailey]

I can understand the confusion Neil. Really the only time you will end up with flat areas is when you are adding contour data. If you are adding breaklines, you shouldn't end up with flat areas unless you want them to be flat areas...

I totally agree with Jeff re: adding the contours as contour data. I don't recommend adding them as breaklines because most likely you are going to need to weed/suplement/flatten them and it's a nice way to keep them organized. Just wanted to expose a bit into the background processing of the data.

[M_RR]

Hi everyone,

I am having the same question ( construct a surface from polyline -3D).

I did follow the instruction ( either add the polyline as a breakline or as contour (contour does not seems to work for me)), the program looks like he's doing the job. I get a new surface with breakline ( I have the breakline listed, all of the 14 000) but then, when I use the prospector to selec my new surface, then use the object viewer, there is nothing in there (even if I change all the display setting). Looks like am not getting any triangle or anything else....

Anyone got a Idea ?

Just to mention that I did insert the polyline as a shape file in the first place (importing from the map module). Then I attached this draw to another draw and modified the property to specify elevation to the polyline (so my polyline produce a 3-D effect). Now I wish to bound them into a surface, but I can't seem to do it ! 

[Neilw_05]

Rather than trying to view the surface with Object Viewer (which may have trouble displaying all those triangles), look at the surface statistics tab in the surface properties. It will report the number of triangles in the surface among other attributes. Of course if the values are zeros then your surface is empty.

Also, try viewing your surface in a true 3D view such as an isometric orientation rather than using Object Viewer.