Creating Varying Mesh Density in Rhino


#1

I am using Rhino the model the hull of a vessel and would like to have a finer mesh near the water line. Does anyone have any ideas on I could achieve this in Rhino?

My initial guess was to try to increase the isocurves at the waterline to see if I could increase the mesh density near the waterline. Can Rhino create a mesh based on isocurves?


(John Brock) #2

What problem are you trying to solve?

There are several ways to increase the number of facets in a render mesh, when creating mesh objects, or analysis meshes. Knowing what problem you are trying to solve would get us pointed in the right direction.

No, a higher number of isocurves displayed in a surface has no effect on meshes created from them or on render or analysis meshing.


#3

This is for an analysis mesh, that we use to perform hydrodynamic analysis. We typically create a surface, mesh and then export to WAMIT. I am trying to reduce the number of overall panels in the model, but would like to have increased panels at the water surface. So the idea would be to have small panels at the water surface and larger panels on the lower parts of the hull. I was able to create a decent uniform mesh, but this created over 7000 panels which is taking some time for the analysis to run.


(John Brock) #4

I guess I would make a copy of the polysurface you’re meshing. Save a then split it so you have separate areas to mesh where the density is important.
Then join the meshes together for export.
It might end up more complicated than that but that’s the path I’d go down first.


(Wim Dekeyser) #5

I would expect that workflow (split - mesh - join meshes - export) to produce gaps at the split. To avoid that you would have to join the surfaces again before you split them. Of course, then you will have to use the same meshing settings on both surfaces and that will likely cause the overall mesh to be too dense again.

You could therefore try to split several times very close together but at different elevations above and below the waterline.

The RH6 WIP allows you to fix mesh points when you use the ReduceMesh command. So you could start with a very dense mesh, lock the vertices around the waterline and then have the rest reduced.


(Willem Derks) #6

Hi Abel,

In the WIP the Reducemesh command now has an option to lock a set of vertices to be left as they are.

I’ll see if I can find the post related to that…

EDIT: the post in question

@Jussi_Aaltonen , maybe for a future updates have functionality to use other geometry eg curves to locally lock vertices. Much like the Shutlining feature operates on the mesh…

-Willem


(Jussi Aaltonen) #7

@Willem That sounds like a good idea. It’s logged: https://mcneel.myjetbrains.com/youtrack/issue/RH-35992