3D Curve Entity AutoCad

Don't know of any curve entity but I do remember a setting for the "mid ordinate" when converting figures to break-lines that defaults to 1.00'. I set it to 0.10' to force the addition of more vertices.

What sacker said.

In the analysis/figures menu under figure settings, set the MO distance to 0.01.

Then, under the analysis/figures menu select create breaklines from figures and name (I usually name it BRK) and select your polylines.

After that you'll be able to import those (BRK) breaklines into terrain model explorer, and they'll show up as curved breaklines.

The tin will look very interesting going around the curves, as there will be many tin lines running from a radius point to the arc.

This is how it is done in LDD, people with Carlson, etc. may have to do it differently.

Without any third-party AutoCAD applications, the closest equivalent to a 3D arc in AutoCAD would be a Helix. The easiest analogy of when to use a Helix is if you'd want to model the threads of a bolt (cylindrical helix) or wood screw (conical helix). In either case, the Helix presumes a uniform slope along the helix itself (but you could certainly model several Helixes in the case of a non-uniform slope). Once the Helix entity is created, it can be exploded into a SPLINE entity which might provide further use for your work.

For the Carlson users out there, the Convert Entities to Polylines routine can change a SPLINE into a standard polyline but they also have (through our Field-to-Finish routine) the ability to generate 2D and/or 3D polylines from points. The "curves" within a 3D polyline are modeled as a series of chord-segments suitable for triangulation within a surface model.

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Ladd Nelson

In Civil 3D, the easiest option is to create a Feature Line, then add that to your Surface as a breakline. It remains dynamic, so if you edit your Feature Line, you see the changes reflected in the Surface.

Thanks all. I found a routine in LDD under the Terrain menu that forces a 3D polyline to follow a curve using very short (2' default) vertices. It's not really a curve but it looks like one. Good enough for breaklines.....

Newtonsapple, post: 79126, member: 1702 wrote: What sacker said.

In the analysis/figures menu under figure settings, set the MO distance to 0.01.

Then, under the analysis/figures menu select create breaklines from figures and name (I usually name it BRK) and select your polylines.

After that you'll be able to import those (BRK) breaklines into terrain model explorer, and they'll show up as curved breaklines.

The tin will look very interesting going around the curves, as there will be many tin lines running from a radius point to the arc.

This is how it is done in LDD, people with Carlson, etc. may have to do it differently.

I followed you up until importing the breaklines into terrain model explorer. The points on my curves are very far apart so I need to have my breaklines curved. When I create breaklines from figures ( this is a first for me) it asks me what surface I would like to add them to so I select my newly created surface. Once I select a curved pline cad is telling me that this lightweight pline will be converted to a regular pline (ok).
No I see that it is now a 2d polyline.... Does this sound correct so far? Could you explain more on the process of importing to terrain model explorer.

Thanks.

sinc, post: 79163, member: 183 wrote: In Civil 3D, the easiest option is to create a Feature Line, then add that to your Surface as a breakline. It remains dynamic, so if you edit your Feature Line, you see the changes reflected in the Surface.

This is what I use for surfaces... seems to be the best way to do it. I could be wrong though, as I don't work with surfaces much