Networksrf rebuild - homogeneus control points distribution for flow?

Rhino Rhino for Windows
1

Hi there to everyone,
Problem si the following: networksrf isocurves (and controlpoints) get defined by my curves, of course. But since its a “manual” process the distribution of them is not perfect. This can be a problem if you want to FLOWALONGSRF something which should look similar.

So, I though: just make a rebuild of the surface and it will homogeneusly distribut the points for the flow to happen. But it doesn´t (as you can see in the picture), parts 1 and 2 have different “density” and that affects the flowalongsrf. ¿Which is then the workflow to follow?

Thanks in advance,
Diego

2

Hi Diego - Rebuild is the way to go, just use a lot of points (on a temporary copy to use as a flow target) to ensure the result is evenly parameterized. But I would expect the rebuild result not to be uneven like the one you show, I think… can you send the surface?

-Pascal

3

Thanks for your quick reply Pascal. No matter how high is the rebuilt value it stays the same…
Attached file and image.

network rebuild2.JPG1164×744 226 KB
network bug.3dm (602.0 KB)

4

Hmm - yeah… thanks - this seems a little unexpected, to me at least, I’ll ask a bigger brain - thanks for the file.

@mikko - can you take a look? I made some wiggly surfaces of different kinds and they seem to all rebuild more evenly than this one.

-Pascal

5

@pascal, looks like the geometry library function that does the actual rebuilding extracts isocurves in the middle of surface domain in both directions, splits those into requested number of pieces and extracts the parameter values of the splits, and uses the extracted parameter values for constructing the new surface. Meaning the rebuilt surface isocurve division should be even right in the middle of the surface, and in many cases uneven elsewhere. Attached is a simple but extreme example. The surface on the left was rebuilt using 10x10 points.

rebuild_surface.3dm (26.5 KB)

rebuild_surface.jpg1152×646 68.7 KB

6

Attached is the surface in question “rebuilt” with 60 x 10 points and evenly spaced isolines. network bug DC 2.3dm (5.1 MB)

Procedure used:

  1. Create a mesh of the surface using Mesh. The lengths of the sides need to shorter than the desired distance between control points in the final surface.

  2. ExtractPt on the mesh to create a dense set of points from the vertices of the mesh. Delete the mesh.

  3. DupEdges of the input surface and Rebuild with point counts corresponding the desired point counts of the final surface.

  4. EdgeSrf with the rebuilt edge curves to create a starting surface.

  5. Patch using the points from the mesh, Starting Surface of the with the surface from the rebuilt edges, Preserve Edges on, and a small value for Stiffness (I used 0.1).

7

Well thanks a lot david, I appreciate your effort.
Although, isn’t it a little bit crazy that all we have to fulfill all those steps to get an evenly distribution of isocurves/controlpoints??

8

Does that mean that there is no official way to achieve an even distribution? No solution in order to apply an homogeneus “flow a long srf”?

9

Hi Diego,

I’m afraid so. The Patch solution above may be the easiest one right now.