Hello,

I’m trying to find the region intersection (preferably as a surface) between a smooth surface generated from other parametric parameters and the surfaces from a mesh projection to c-plane (generated from showing strongest water flow over a topography). Although the triangles are now surfaces they don’t seem to join into one surface and region intersection doesn’t work with them. Another way could be to extract the naked edge of the mesh projection and then use the surface from this to find the region intersection but finding that outer edge doesn’t seem to be working either.

I’m quite new to grasshopper so apologies if the answer is really obvious, I’ve been trying lots of different ways and nothing is working! I’ve attached the .gh and .3dm below, and internalised the data.

Thank you in advance!

Lizzie

20230321 Water Flow Mesh Projection Forum Help.3dm (18.8 MB)

20230321 Water Flow Mesh Projection Forum Help.gh (4.4 MB)

If your mesh projection to the c-plane is now planar, can you create a `BoundarySurface` from the naked edges and then use this for your region intersection?

You might have some problems where you have triangular gaps in your mesh and might need to either tidy these up manually or hope the boundary surface works OK with them in (it can deal with holes normally)

Something is weird with your 3dm file too… it says 18Mb but it only contains that small surface.

You could also try and use `TrimWithRegion` from the Intersect>>Region Tab

Try `MeshShadow` to create the curve on the XY plane from your flowlines mesh and then Region Intersection with the outline of your other surface.

Hi Marty,

Thank you so much for your quick reply!

I’ve tried boundary surfaces, mesh shadow and trim with region, but they all are coming up with errors, although I’m not sure why? The boundary surfaces worked for a minute, but I’m hoping to do this with the aim to test a group of points for whether they are in the intersected surface, and when I plugged the intersection in (when it was working) no points showed even though I can see that they are included.

I’ve now included this part of the script too apologies for not including that at first!

20230321 Placing Buildings Exclusion Zones Circle Packing Working Mesh Problem.gh (1.1 MB)

Thank you

Lizzie

So I think your problem lies with your water flow mesh. It’s not a great mesh in terms of it having non-manifold edges etc. I tried to repair it using rhino’s MeshRepair but it crashed my PC!

I tried remeshing it with TriRemesh and QuadRemesh but neither could deal with it.

How exactly are you generating that mesh? Is there a way to reduce the amount of mesh faces?

I think if you fix that mesh then the rest of the process might be easier.

Hi Martyn,

Apologies for the late reply!

I am building the mesh from a series of points that show the water flow over a surface, I then cull faces of the mesh based on their area, then the aim is to intersect that shape with the shape from a slope analysis, to then do a point in curve/brep analysis.

I have attached a file with a fuller script, the data is internalised but I have also attached the rhino file so you can see it working. If you know of a better way to keep the closest clusters of points and then draw a ring around them that would be amazing! Sorry it’s a problem with many steps!

Thank you again for all your help!

Lizzie

20230321 Water Flow Mesh Projection Forum Help3.3dm (128.5 KB)

20230321 Water Flow Mesh Projection Forum Help3.gh (83.7 KB)

OK, I had to use a plugin called Alpha which creates a boundary around the projected water flow points. I filtered out some of the flowline points using a circle because they were making it really hard to mesh.

It’s not a great solution but I think it gives you what you need?

20230321 Water Flow Mesh Projection Forum Help3.gh (101.8 KB)

alphaShape.gha (22.5 KB)

Yes! This looks like exactly what I need! Thank you so much for your help!!!

1 Like

Hello again,

I’ve just moved this script off a tester surface and onto the actual topography and it has created a strange set of curves that won’t interact with the region intersection in the next section. I can’t figure out what’s different, I’ve attached the script I was helped with with the new more complicated surface. Please help!

Thank you!

Lizzie

20230322 Building Organisation Mesh Help.gh (1.5 MB)