When adding data to a surface, there is the option to add it as a "Non-destructive" breakline.
http://screencast.com/t/qBnciKzR3i
What is this good for? I created a surface, copied it, and created a volume surface between the two of them. As expected, the resultant volume was 0.
I then draw a 3d polyline and snapped to elevations on the surface. I then took that 3d polyline and moved it up 5'. I then added that breakline to the surface as a "Non-destructive" breakline and the resultant volume between the original surface and the one modified with the new breakline was still 0. Absolutely no change was made to the actual surface, it just added additional triangles.
Anyone have any idea why anyone would ever use such a thing? I'm trying to find a reason it's even option and I'm coming up blank. There has to be SOME reason it's there.
I've used them rarely, but there have been a few times when I needed to preserve the existing TIN either inside or outside of a closed area before adding new data to the surface. A non-destructive breakline is useful for that purpose.
I suspect that the "non destructive" part (as sboon suggested) does what it says - it merely preserves the original TIN structure but with additrional TIN lines at where the non destructive breakline crosses the TIN.
From the help "....The elevation for each new point is extracted from the original surface triangle, therefore maintaining the integrity of the original surface..." so the line could have been raised 100 feet and it still wouldn't have affected the TIN
I also use them in the same way as mathewk and sboon do as I guess this is the intended use.
neilyj (No connection with Autodesk other than using the products in the real world)
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I would define a "non-destructive Breakline" as a "projected contour" added to the surface definition.
It does NOT affect the curvature of the C3D surface, just adding triangles to it.
So what is the purpose of these things? In the context of breaklines (not boundaries) I can't see any use for them either. A breakline that doesn't influence the surface isn't really a breakline in my thinking.
Neil, I think Steve got it. You can use it to create a breakline on the existing surface before you perform edits on one side of it. If you paste a surface onto a larger one, for example, C3D will triangulate from the edge of the surface you paste in, to the nearest data on the larger surface. If you were to add a non-destructive breakline first you can control where that match point will be.
I had never looked at these, never used them. But I have used feature lines to do something similar: draw feature line, elevations from surface (add verticies), add feature line back into surface to make sure that it doesn't change at this point, while I edit nearby. Non-destructive breaklines look like a better way to go for that.
This is why I love coming here: always new ideas floating around. (New to me anyway.)
Mark Green
Working on Civil 3D in Canada
Ok I get it now. I assumed it ALWAYS maintained the triangulation of the TIN, but after running some tests I see that it's position in the surface definition is a factor. Good to know.
That sounds about right. I think I've seen post that describe exactly what you're talking about. Thanks for figuring it out.
Allen
Allen Jessup
CAD Manager - Designer
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I have an design surface and also have multiple surveyed existing ground surfaces that need to be pasted into the design surface for quantity calculations. I can't figure out how to hold the integrity of the design surface outside of these little existing ground surfaces. Outside of all my existing ground surfaces, the tin lines are interpolated to the next design tin line instead of keeping the design surface elevation. I've tried the non-destructive breakline approach and maybe I'm doing something wrong, i don't know. Any help would be appreciated.
thanks
I use them to calculate areas at various slopes within proposed lots to meet zoning ordinance requirements.
I trim the surface along the proposed lot lines.
A great place to use them are when doing curbs around tight geometry. Say you have a Curb island where you need to model the curbs precisely; or a driveway with curbed flares that need to be modeled. You can model the base elevation as a giant box, then use non-destructive breaklines to get the radius geometry squared at the elevations you want with the surface fidelity you want. Then you can offset and add your TC curb line.
If you had added breaklines using the "Standard" method and your curvature is high, you might end up otherwise warping the contours.
Another good use is if you geometry you need to trim around. Say you have a building with a column that sticks out - you can quickly define your surface ignoring the column, go back and place a non-destructive around the column. And then trim your surface around the column using your new triangles.
A neat trick is that once you have added the line to the surface using non-destructive methods, you can go back and pull the elevations onto the line, preserving them should your featurelines get jumpy on you.
Interesting! Good to see some other uses.
I have not really changed. I don't trust anything but standard. Proximity & wall breaks give me heebie jeebies or fits. Since this post was created almost 10 yrs ago 99.9% of my breaklines are still standard breaklines. I have probably created 20,000+ breaklines in that time. I wonder if any of the other original posters have used them more than they did.
John Mayo
I think I know what you mean by giant box but can you clarify that for me
Joe Bouza
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The vast majority of my breaklines are defined as PROXIMITY.
For the benefit of those reading this post who are unsure of the difference, it's not about trust, it's about understanding the tools. A simplistic explanation follows.
Proximity: simply flips the triangles around so that when possible, no TIN lines cross the defined breakline. Use 2D entities with this option. Edits to these DO NOT result in the surface being modified because by default, when you define Proximity breakline, they get converted to 3D entities and stored as Standard breaklines, but there is an option for this in the surface build options. Also, if your polyline drafting skills are not perfect and you miss some OSNAPs, this option will move the missed vertex to the closest surface point, thus Proximity.
Standard: flips the triangles the same as Proximity, BUT this option adds the Z coordinate of the polyline vertex to the surface definition if no other surface point exists exactly at that vertex. Imagine a 2D polyline at elevaiton 0 accidentally gets defined as a standard breakline. If a vertex is not perfectly coincident with a surface point, you'll have contours going down to 0 at that location. Use 3D entities with this option. Edits to these breaklines result in the surface being edited when they are modified and the surface rebuilt.
There is no right or wrong answer here and both have their pros and cons, or at least both have their own things that can backfire on you.
Yes trust was a bad term to use. 🙂 Surveyors use proximity breaks more with conventional survey data but this becomes an approximation of what was really shot. Not my recommendation for survey workflows. Especially with field to finish. It’s mostly design on my end and I want exact break lines. Not the closest point at a vertex. There are also very few coho points in me designs. Yes this is opinion and need but The break lines I create are usually the things I am building and staking out. I want exact xyz. My workflows in survey and design have little use for anything but standard but Matt, you are correct. Knowing what each does is very important.
Regardless of my opinion, you and Joe didn’t answer. Have you used them more since the original post? Are you surveying or designing?
John Mayo
I use proximity proximity now the same as I always have. When I was in production I was drafting and designing.
I can see the benefit of using proximity breaklines when you already have data in the surface (such as point data). I typically don't use any other elevation data for my surfaces except breaklines (assuming I'm not using corridors or the grading tools). I use the breaklines to assign the elevation and the triangulation at the same time. One method isn't necessarily better than the other, just different.
As for the original question from John, do I use non-destructive breaklines? On a rare occasion I will but not very often. I like that they are there but I can get the same result by draping a polyline or featureline on the surface and then adding it as a breakline.
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