topic Re: Breaklines and topos in Civil 3D Forum

Breaklines and topos

ESchomberg — Thu, 26 Aug 2021 01:40:37 GMT

Hi friends, I have asked about this before but never got a resolution so I am hoping that the right person sees this.

I made up a bunch of points to mimic a topo with a top of bank and a toe of slope.

1) I used regular lines as breaklines and it made the topo go haywire.

2) I used 2D polylines as breaklines and the topo went haywire.

3) I used 3D polylines as breaklines and the topo went haywire.

4) I used Feature lines as breaklines and it came out beautiful.

The problem is......you can't hatch Feature lines so if you use Feature lines you end up drawing the same lines twice with a different line type just so you can hatch it. For this reason my co worker said he will not use feature lines.

So what gives here? Feature lines seem to be the only lines that work correctly for me as break lines. Can someone either tell me how to hatch break lines or either explain what I am doing wrong? This is a really big deal for my topo purposes. Thank you.

Re: Breaklines and topos

rl_jackson — Thu, 26 Aug 2021 01:59:53 GMT

@ESchomberg, if you could post a picture of what you want the final product to look like it might help, not sure why you would be hatching breaklines, I don't even show them, show of the hard surface stuff like curb, back of walk etc....

2dpolylines can be breaklines, but you must use the PROXIMITY option, this selects the nearest point (technical this would have been used to draw the line, I don't do this)

3dpolys are a pita, I will used FL's but almost exclusively use survey figures, which are never in the "surface" drawing, unless I feel I need them.

Re: Breaklines and topos

samir.rezk — Thu, 26 Aug 2021 02:05:46 GMT

Hi @ESchomberg

Feature lines is the recommended best practice for designing proposed grade! Feature line are easier to manipulate either graphically or in a tabular view where as 3D Polylines are a bit more work to set their elevations and they don’t support arc segments!
However, I think the main reason the surface is not producing the correct intent is not because the object used but rather because of the Breakline type!
A traditional Standard Breakline type will apply the object elevations to the surface (often used in lieu of points) the TIN will inherit the object elevations! So we must be cautious the 2D Poly/3D Poly or Feature Line actually have desired elevations to apply to the surface. In your case, the desired TIN elevations are set by Cogo points, so the Breakline type should be set to Non Destructive Breakline this type will break the TIN at the linework locations but will not have an impact on elevations at all.

My theory, is that when drawing Feature Lines, you automatically inherit the Cogo point elevation you snap to, there by producing a Feature Line with desired vertex elevations matching the points.

Hope this helps,

Re: Breaklines and topos

ESchomberg — Thu, 26 Aug 2021 02:45:03 GMT

There are occasions where hatching is needed between break lines. What did you mean by 3d poly lines are pita?

Re: Breaklines and topos

ESchomberg — Thu, 26 Aug 2021 02:50:08 GMT

So what type of line/lines would you use for standard breakline?

Re: Breaklines and topos

samir.rezk — Thu, 26 Aug 2021 02:53:21 GMT

Hi @ESchomberg

I prefer Feature line, but in reality any object is appropriate for a Standard Breakline so long as the object contains desired Z values. The object elevation has a direct impact on the TIN elevation (exactly like points!)

Re: Breaklines and topos

rl_jackson — Thu, 26 Aug 2021 02:57:39 GMT

NONE, if your drawing point to point and the point style is flattened (at 0), use proximity breaklines to have C3D read the nearest points elevation to the line.

PITA (PAIN IN THE A$$) They don't do curves like polylines, and featurelines or survey figures.

Re: Breaklines and topos

ESchomberg — Thu, 26 Aug 2021 03:04:20 GMT

The point style is flattened at zero.....I don't understand that. Wouldn't that make contours impossible?

Re: Breaklines and topos

neilyj666 — Thu, 26 Aug 2021 07:15:15 GMT

Can you share the dwg as it'll save a lot of pointless (!) message exchanges?

Re: Breaklines and topos

Pointdump — Thu, 26 Aug 2021 07:46:02 GMT

Hey Erik,
"There are occasions where hatching is needed between break lines."
If you can't share the drawing, at least give a screen shot of one of these instances.

Dave

Re: Breaklines and topos

Jeew-m — Thu, 26 Aug 2021 08:49:29 GMT

As many of us suggested I wish you could upload a sample drawing.

In theory, standard break lines refer to 3D polylines.

Proximity break lines refer to 2D polylines.

However, in 3D polylines, there may be a vertex at the middle which has an elevation of 0. That can ruin the surface.

I sometimes create a quick profile from a 3D polyline to verify that it has accurate data.

Re: Breaklines and topos

Udo_Huebner — Thu, 26 Aug 2021 09:06:04 GMT

@ESchomberg

As I understand it, everything works fine with Featurelines, except the hatching between FL does not work as expected. But that can be adjusted.

If the 3D Geometry Display Mode settings for the Site are set to "Flatten to elevation" to 0, the Featurelines are only displayed in Elevation 0 and can be hatched just as 2D Polylines, while the Surface is modeled from the same Featurelines as breaklines at the correct height.

Here is a short Screencast: https://autode.sk/3B8COWe

Re: Breaklines and topos

neilyj666 — Thu, 26 Aug 2021 11:30:30 GMT

@Udo_Huebner top tip - I have never used this setting before although I've seen it but didn't know any practical use for it. I think I'll be using it a lot from now on...😁

Re: Breaklines and topos

Anonymous — Thu, 26 Aug 2021 12:19:08 GMT

@ESchombergthe reason your lines and 3dpolylines are not working is because your point nodes are flattened to zero. So your breaklines acquire elevation 0 and the surface goes haywire. Edit the point style or create a new one that uses the points elevation for the node elevation. Set your running osnap to node and draw the lines/3dpolylines in from node to node. It is less useful but way easier to draw than feature lines. they should work fine for breaklines.

A good idea when you are creating a surface is to (SAVE first) use 3DORBIT and spin the surface objects around in 3D to check that it looks right. It becomes immediately clear that it isn't right when you see objects at elevation 0, or shooting down to zero from a valid elevation t the other end.

Re: Breaklines and topos

ESchomberg — Thu, 26 Aug 2021 12:46:00 GMT

I talked to my company cad man and thats exactly how they do it. They select all lines, convert them to 3d lines then convert them to 2d lines then flatten them all

Re: Breaklines and topos

ESchomberg — Thu, 26 Aug 2021 12:48:05 GMT

Its not a drawing, I just made up some random points to mimic a pond topo however the template I used is someone that does not want me posting his information

Re: Breaklines and topos

ESchomberg — Thu, 26 Aug 2021 13:47:29 GMT

Ok give me a little time to play with it, if I can't figure it out based on the info I have, I will do a screen cast

Re: Breaklines and topos

ESchomberg — Thu, 26 Aug 2021 13:56:33 GMT

I am interested in what you are saying, it just seems that flattening a feature line would defeat the purpose of creating one. I could be wrong

Re: Breaklines and topos

fcernst — Thu, 26 Aug 2021 14:02:41 GMT

Just see how the Points do themselves triangulating..then just flip a few faces to enforce a breakline behavior where needed and be done...

Re: Breaklines and topos

ESchomberg — Thu, 26 Aug 2021 14:56:02 GMT

Could you better explain when it is appropriate to use non destructive break lines?