topic Re: Mesh . . not able to elevate contour or node with out er in Modeling

Mesh . . not able to elevate contour or node with out error

Anonymous — Thu, 25 May 2023 15:09:27 GMT

I have a mesh I have been working with for a while no with no problems, and now everytime i try to do any little thing to it I get invalid polygon messages.

"Invalid Polygon, Self intersection or hole intersects boundary."

Even if I don't change anything it does it, like I just went to a contour and said go to Z value, and didnt change it, just said OK, and it still gave me the rror message.

Re: Mesh . . not able to elevate contour or node with out er

Anonymous — Tue, 06 Jan 2009 21:03:44 GMT

Do you have a self intersection or hole intersecting a boundary ?
Does the mesh process in 3D ? Meaning, does it show in 3D ?
Peter Devlin

Re: Mesh . . not able to elevate contour or node with out er

David Maudlin — Wed, 07 Jan 2009 16:12:09 GMT

Jess:

I have occasionally run into this error message, generally when magic wanding a site boundary from lines and curves, where one of the lines does not exactly meet the end of the curve, creating 2 nodes rather than one. Unfortunately, the only solution I know of is to turn off True Line Weight and zoom in really far on suspect nodes to see if there are 2 rather than 1, then combine the 2 nodes.

HTH

David

Re: Mesh . . not able to elevate contour or node with out er

Laszlo Nagy — Wed, 07 Jan 2009 16:44:28 GMT

Jesikuh123 wrote:
I have a mesh I have been working with for a while no with no problems, and now everytime i try to do any little thing to it I get invalid polygon messages.

"Invalid Polygon, Self intersection or hole intersects boundary."

Even if I don't change anything it does it, like I just went to a contour and said go to Z value, and didnt change it, just said OK, and it still gave me the rror message.

This means that you mesh geometry is already incorrect so you will keep getting that error message. Maybe you should redo the mesh.

Another advice is useful when tracing level lines coming from the surveyor. If is a good idea to run Line Consolidation on those lines so any overlaps that could be causing wrong mesh geometry when traced, will be handled.

Re: Mesh . . not able to elevate contour or node with out er

Anonymous — Wed, 07 Jan 2009 21:53:25 GMT

The reason I asked the questions I did is that there is one
situation where there are no self-intersections yet an
intersection error is reported and the mesh fails to process
in 3D. Answering those questions would have helped me
know what the situation was and I might have been able
to suggest a solution. Please see this thread.
http://archicad-talk.graphisoft.com/viewtopic.php?p=132707&highlight=semicircular+mesh#132707
Peter Devlin

Re: Mesh . . not able to elevate contour or node with out er

Anonymous — Thu, 08 Jan 2009 15:17:18 GMT

How would I know if I have a self intersection?
As for the holes intersecting boundaries, probably. I have been messing with this for a while now, and I can't remember exactly what I have done to it, but I have put holes in it, and yes they probably intersecting boundaries.

I think I am going to just redraw the whole thing.

One weird thing that does happen is even if I don't get an error message, if I change a contour or node, all of my contours disappear and I am left with just dots(nodes). Glitchy?

I actually have a million more questions on meshes.

1. I have a whole bunch of nodes at the base of my mesh the connect with lines that you can see in the 3D window to nodes at the top edge of the model.

2. I have nodes at the base of my mesh that have nodes right above them on t he top edge of my mesh with no connecting line, I keep trying to combine these nodes with other ones to get rid of them and I get error messages, or they just wont move at all.

3. sometimes when I do get them to move I am left with just a like 1 node contour line on the top of my mesh that I don't know how to get rid of.

4. sometimes when I am trying to move the end of a contour line, it just adds to the contour. So, I mean, if I have a contour line that is a straight line, and I try to move the end node of it, I will end up with a contour that is the shape of a "Y".

oh, and there is more.
I didn't really have these problems when I was just creating meshes for site plans, and then being done with them.
But now, I am trying to adjust/change an existing site to a proposed site and things are going nuts.

When you guys are doing this, do you just start the mesh all over again, or do you edit the existing site mesh?

Re: Mesh . . not able to elevate contour or node with out er

rocorona — Thu, 08 Jan 2009 16:34:53 GMT

If the Mesh is too complex for a complete redrawing, make a copy of it (maybe in an new empty file) and trace a series of lines crossing the surface. Use the lines to cut the Mesh in a series of smaller ones (DIVIDE command). Then try to modify each of them until you find wich is the problematic. Divide again then, when you have few nodes you can try to find the error and correct the perimeter.

Re: Mesh . . not able to elevate contour or node with out er

Anonymous — Thu, 08 Jan 2009 17:08:17 GMT

Jesikuh123 wrote:
When you guys are doing this, do you just start the mesh all over again, or do you edit the existing site mesh?

Most of the time I find it easier to do a new mesh for the grading plan. Particularly if the changes are many and complexed.This has the added bonus of SEO potential for cut & fill raw quantities.

A while back when doing a large (30 acre) steep (600' differential) site with 2' contours I kept getting pyramid shaped divets with the point node at the bottom of the mesh. After starting over 2 or 3 times I finally started with a flat mesh and then set the four corners to elevation prior to starting on the contours and everything worked. I now do this on all site meshes.

What I have yet to figure out is when elevating a contour line,using "apply to all", how to get the nodes at the edges of the mesh to elevate too.

Dave

Re: Mesh . . not able to elevate contour or node with out er

Anonymous — Thu, 08 Jan 2009 20:26:44 GMT

Hello Jess,
You wrote:
"One weird thing that does happen is even if I don't get an error message,
if I change a contour or node, all of my contours disappear and I am left
with just dots(nodes). Glitchy?". The reason this happens are many but
you must do an "undo" or your mesh is permanently destroyed.
Some of the other things you mention are the way the mesh tool works.
About your "million questions", I have written something
called "Mesh Tool Notes" that is just some of my observations about
how the mesh tool works and how to work with the mesh tool.
It is a .PDF and it might be helpful to you. Please see attached.
Peter Devlin

Re: Mesh . . not able to elevate contour or node with out er

Anonymous — Fri, 09 Jan 2009 16:38:31 GMT

Hi Peter.
I am reading through your mesh notes you atached and I hve a couple of questions:

1. It tells how you can add points with out creating ridges. Do you use this option, and what would you use it for?
1a. it also says to not use surface fitting, what is surface fitting and why wouldn't I use it? I always leave it checked.

Re: Mesh . . not able to elevate contour or node with out er

Anonymous — Fri, 09 Jan 2009 20:02:13 GMT

Hello Jess,
One of the most common uses of independent points
is when say you want a swale that is between two adjacent contours.
You do not want a ridge line that is between your standard contour intervals.
Any time you want to manipulate the grade between standard contours
intervals you use independent points.
Surface fitting is where AC creates a mesh contour line whose nodes
lie on the surface of the mesh as it is at each new node point. The
consequence of this is the elevation of each node is different even though
they lie on the same contour line. The whole system of contour lines is that
all points that are at the same elevation form a contour line. So you do
not want to violate this system by having a contour line that has nodes
that are not all at the same elevation. I recommend, and some disagree,
is when creating a new contour using the magic wand do not enable
surface fitting which creates the new contour with all nodes at zero
elevation but they are all the same. Later you assign all of those nodes
the elevation you want.
One important use of surface fitting is when you want to show with a line
where the terrain intersects some element like an exterior slab and don't
want to cut a hole in the mesh to get this intersection line. You draw a
line around the perimeter of the slab select the mesh, turn on the mesh
tool, and magic wand this line but when prompted you select the
surface fitting option. Since these kinds of lines are not official contour lines
but object lines they can have nodes of differing elevation.
I hope this makes sense.
Peter Devlin

Re: Mesh . . not able to elevate contour or node with out er

Anonymous — Fri, 09 Jan 2009 21:37:47 GMT

Hello Jess,
I would like to refer you to two links that have discussions about meshes.
The first is to James Murray's site and his discussion of terrain meshes.
http://www.onland.info/archives/2008/08/mesh.php

The second is a discussion by Lazlo Nagy on ArchicadWiki
http://www.archicadwiki.com/Mesh

James' discussion is quite extensive and is excellent .

Lazlo's discussion is more specific but also excellent.

Peter Devlin