topic Re: Splitting merged contour lines (mesh) in Modeling

Splitting merged contour lines (mesh)

Anonymous — Thu, 25 May 2023 14:59:26 GMT

I have received a DWG with contour lines for a terrain. Unfortunately, two contour lines intersect and is regarded as a closed polygon by ArchiCad. That means that when I now want to change the mesh point height of one of these contour lines (selecting a point and clicking "Apply to All"), it selects and changes both contour lines ... This results in me having to go through each and every point in the two contour lines and elevate each point manually. Quite a painful task as I am dealing with approx 800 points in each!

Is there any way in ArchiCad to split one contour line into two?

Essentially we are just talking about splitting up a polygon/mesh.

P.S. If the terms are wrong or confusing do tell me, and I can try to reword or explain more, perhaps using some screenshots or simplified example.

Re: Splitting merged contour lines (mesh)

Anonymous — Tue, 14 Oct 2014 08:31:48 GMT

I am wondering if the lack of replies is due to a too vague or confusing description of the problem, or if it simply due to there not being a way to do this in ArchiCad.

Re: Splitting merged contour lines (mesh)

Barry Kelly — Tue, 14 Oct 2014 08:52:15 GMT

Can you show a screen shot of how the contour lines intersect?
Ideally with the mesh selected so we can see the node positions on the contours.

Barry.

Re: Splitting merged contour lines (mesh)

Laszlo Nagy — Tue, 14 Oct 2014 19:06:06 GMT

Can you select one of the intersecting ridges by clicking on one of its edges? Then move that node that is at the intersection point of the two edges?
I tried it in a new project and when I did that I could pull that node of one ridge away from the common node. Then it was possible to set the heights of the two ridges separately.

Re: Splitting merged contour lines (mesh)

Anonymous — Wed, 15 Oct 2014 21:47:23 GMT

Thank you both for answering - I am sorry that I was unable to reply this morning, Barry. Will try and post a screenshot once I get to work in the morning!

I will also try out the tip from Laszlo ASAP.

Re: Splitting merged contour lines (mesh)

Anonymous — Fri, 17 Oct 2014 08:24:46 GMT

Here is a detail and an overall picture (next post) of the landscape I am working with. It is very difficult to tell which intersections that are causing the problems due to the complexity of the landscape file.

Re: Splitting merged contour lines (mesh)

Anonymous — Fri, 17 Oct 2014 08:26:27 GMT

And the overview picture ...

Re: Splitting merged contour lines (mesh)

Barry Kelly — Fri, 17 Oct 2014 10:11:55 GMT

It looks like you should be able to drag the nodes to separate the contours.
Not an ideal solution as you shouldn't be moving the contours but then they shouldn't be crossing in the first place so there must be an error from the original DXF.

Barry.

Re: Splitting merged contour lines (mesh)

Anonymous — Sat, 18 Oct 2014 12:05:23 GMT

Unfortunately erronous and/or incomplete terrain models from the city planning office is the norm rather than the exception here in Norway, so intersecting contours is just a fact of life one needs to deal with on a daily basis ...

Trying to drag one node affected other nodes in unintended and surprising ways, so I was unsuccessful in going in that direction. That was why I was hoping to circumvent the problem by splitting a contour line before the intersection point.

Thanks for your help anyway!

Re: Splitting merged contour lines (mesh)

Laszlo Nagy — Mon, 20 Oct 2014 15:35:54 GMT

What if you cut a small hole around the intersection of the two ridge lines, then delete the hole? That will definitely separate the two ridge lines from each other as it will result in 3 ridge line segments.

Re: Splitting merged contour lines (mesh)

Anonymous — Tue, 03 Feb 2015 15:49:37 GMT

I don't think you can find in nature contour lines (lines with equal elevation) that intersect each other because they lie on parallel planes perpendicular to the Z vector (vector of gravity). Maybe the one line is a boundary line or ridge or constraint that just follows the terrain. I have made two videos on how to model properly a terrain. The one shows how to make excavation pits, plateau, how to cut contour lines that are already applied on terrain, how to calculate cut and fill volumes and schedule them. The other one shows how to make a river, how to make the banks and the water body. You can look up in YouTube under Archicad excavation and archicad river.

For your case you should dinstinguish which are the contours, finish the natural ground with these, and after you finished, you can apply the other lines that can follow the terrain ("All Ridges" selection).

Re: Splitting merged contour lines (mesh)

Anonymous — Tue, 07 Nov 2017 23:55:02 GMT

laszlonagy wrote:
What if you cut a small hole around the intersection of the two ridge lines, then delete the hole? That will definitely separate the two ridge lines from each other as it will result in 3 ridge line segments.

Genius Laszlo. Thanks!