Creating boundaries around densities of points

[Lizzie_Higham]

Hello!

I previously posted this topic, which was resolved for a more simple surface. I am now trying to create the same output of a curve around the most dense areas of points from a point cloud generated from analysing topography for water flow.

I thought I could possibly do this by culling points based on their distance from other points and then using alpha shape, or using rectangle, then culling points whose rectangles don’t intersect with other, and then using region union. I thought another option was creating a quadmesh and then colouring the squares based on how many points are in them, and then culling based on colour mesh and using the boundary.

I have been trying these, but trying to apply this to larger set of points keeps crashing the set up. Could someone help with either a light way of doing this or how to apply the current method to a large set of points?

I have attached the gh. with internalised data and a link to the previous topic. Please help!

Thanks
Lizzie

20230322 Building Organisation Mesh Help.gh (1.9 MB)

Region intersection between a surface and a projected mesh

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 fi…

[laurent_delrieu]

You can make a Voronoi with points
Then measure the surface of each cell
The surface will be the metric you apply on each point of the point cloud (Voronoi cells in Garsshopper are in the same order as the input points, just look that there is no duplicate points)
You can then apply some Kernel Smoothing

Kernel smoothing of mesh

Here the code /// <summary> /// Voir https://en.wikipedia.org/wiki/Kernel_(statistics) /// </summary> /// <param name="arg_meshECEF"></param> /// <param name="arg_tab_values">Values to be smoothed at mesh vertex</param> /// <param name="arg_KernelSize">Size of kernel, same unit as mesh</param> /// <param name="arg_logInterpolation">if true, arg_tab_values will be smoothed using thes log values</param> /// <returns>array of smoothed…

[Lizzie_Higham]

Amazing thank you!

[laurent_delrieu]

Here is a script.
The main things are:

• Cull Duplicates point (tolerance =1)
• Delaunay mesh (to have a mesh to cut)
• Voronoi to calculate the surface, I add an offset in order to not divide too much the polygons on the border)
• Some area treatment,
• Then mesh iso splitting (component now on Nautilus plugin)
  
  
  
  No filtering
  
  
  
  100 m filtering
  
  

Filtering is very long (30 s), I made hundred of simulations of debris falling on earth and I didn’t remember it was so long. I’ll have to look in the files I really used.

Some change in coloring logic and also calculation logic (parallel calculation). It could be optimized more, with RTree for example or some grid. If kernel is 100 m, looking at 400 m is enough.

filter data points.gh (2.1 MB)