Creating a surface from points


#1

I’m still new to Rhino, so my apologies if this is obvious, but I’ve not been able to get this to work.

I have a huge (about 200,000) set of points created with Paneling Tools. The majority of the points are at 0 on the z axis, but one group of them is at z +1, another group at z +2, another group at z +3.

I’m trying to create a surface from all of these points, to make a sort of undulating topography. It seems like there are so many points that when I create a paneling grid the program takes a very long time to respond, if it responds at all. I don’t need to preserve all the points, just have a surface that registers the change in the z axis as bumps.

I suspect this is really a noob issue, but would appreciate any help!


(Pascal Golay) #2

Hello- Patch would be the first thing to try- you may need to monkey with the stiffness setting to get it to register the Z the way you like it. Also, I don’t think I’ve ever handed Patch 200,000 points, I have no idea if that is a good thing or not, but if most of the points are at Z=0 then you may be able to ignore a lot of them.

-Pascal


#3

One other way I go about this sometimes it to make a mesh from the points - either using Rhino’s MeshPatch or the Delaunay component in Grasshopper - and then using Drape, drape a surface over the mesh. You can control the surface point density with the Drape command line options. Or, instead of using Drape, once you have the mesh, you can use Contour to cut a series of parallel sections through the mesh, Rebuild the section curves (and adjust if necessary) then Loft a surface through the sections…

–Mitch


#4

Thanks for the responses, you two.

Pascal: It seems I have too many points to patch them all at once. When I try I get an error message. No doubt it’s my ignorance, but if I break the points into 4 pieces and patch them separately I just can’t seem to get the effects I want.

Mitch: It seems I have too many points again to do MeshPatch (I haven’t used Grasshopper, so avoided the Delaunay component) on all or even a quarter of the points at once, but when I follow your instruction on a small sample it gives me the effect I’m looking for. I’ll try dividing the points into small enough quadrants and join them at the end.

Another method I tried which worked, but required a lot of hopping back and forth between programs, was turning the points into gray scale colors in Photoshop and using the Heightfield from Image function. It was starting to give me the effects I wanted, but wasn’t as easy to modify on the fly as I’d like.

Thanks very much to you both for your help!


#5

OK, in that case Grasshopper/Delaunay will almost certainly be better than either MeshPatch or Patch, it should take 200K points without too many problems… OK - I just tested here and it makes the mesh in around 5 seconds with 200K points, bakes it more or less instantly. Yes, I have a brand-new fast machine, but still - it will be pretty quick no matter what. Draping that mesh with a 100 x 100 CP suurface only took one second here as well.

–Mitch


(Andres Gonzalez) #6

Great Idea…