Point density from a coloured mesh

[sreehari793]

is there any possible way to get the point density(with their average distances) from a coloured mesh in grasshopper, the and then split the point list in three parts according to RGB?

[PeterFotiadis (Pfotiad0)]

Kinda like what Charles wanted in this thread ?

Discretise mesh but keep valid groups/topology

Thanks peter. I’m looking at the K-means implementation in the Accord library but it’s not clear how I would sort the faces alongside the (averaged) face colour? May I ask which implementation of Kmeans you’re using and if you’re happy to share it? Thanks, Charles

[sreehari793]

im sorry , im pretty new in grasshopper …i didn’t really understand the kmeans implementation but im looking for something similar to this and further splitting this into 3 list of points according to the color of he mesh

[PeterFotiadis (Pfotiad0)]

Er … what represent the circles?

Other than that you want:

1. to get the mesh vertices average distance to their neighbor vertices (you need a VV mesh connectivity for that one like the one that Sandbox does [V for vertex]).
2. to “group” mesh faces (the term is: cluster by the way) according to the average RGB value (if available: meaning that if the mesh has colors assigned to vertices) of their adjacent vertices. That said this “grouping” can vary in size according to your desire.

[sreehari793]

thank you for help !!
i have tried something similar but did not have much luck , the points aren’t populated according to the color gradient and nor i can split the list of point into their respective colors.colored mesh.gh (299.0 KB)

[PeterFotiadis (Pfotiad0)]

You are using an add-on that I don’t have.

Save a colored mesh (any mesh) in a R5 (not R6) format and post it here (as R5 file, that is). Then we’ll see what we can do for this case (but using things that you’ll not like like C# code).

[laurent_delrieu]

As a color is 3 values you must define a distance. For example brightness …

Formula to determine brightness of RGB color

Here a simple way to populate depending on height

You could also use that

Circle packing based on image sampling

[sreehari793]

i think i partially understood the formula part . but the main intention is to split a mesh color pattern into three (based on brightness) and i don’t know how to implement it in grasshopper?

[laurent_delrieu]

If you want to split mesh search for mesh Iso splitting I put some script
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.grasshopper3d.com/m/discussion%3Fid%3D2985220%253ATopic%253A1761230&ved=2ahUKEwjGuLGw97_hAhUl5uAKHa2hAUIQFjAAegQIBBAB&usg=AOvVaw2HKlj3CHGEy7g7wMDiXocl&cshid=1554707218082

Implicit surfaces

Hello Petras I have done a multiple iso splitting of mesh. It didn’t use exactly this algorithm. Hope it could help. [Canvas at 07;42;41] multiple_iso_splitting_mesh_LEGACY.gh (17.9 KB) See also these discussions

[sreehari793]

i have been trying the previous methods but still can’t manage to get point density based on colored mesh …the previous method are still very confusing and not giving desired results

im trying achieve something similar to this Capture|333x386 can someone please give a similar solution same as the picture
form01.gh (179.5 KB)
help will be much appreaciated !!!

[laurent_delrieu]

Here is a solution, as I have not searched for the equation on the gradient, here is a way that will work if you stay in Grasshopper Gradient.It uses the fact that Color is transformed to point in Grasshopper, points that are in a cube from {-1,-1,-1} to {1,1,1}
I put a Graph Mapper in order for you to tune the density of points.

I

from_gradient_to_populate_points.gh (190.0 KB)

[marinia]

I am so sory but this script is not working. It does not populate the points, just does the grayscale thing…

[laurent_delrieu]

I am also sorry. You 'll have to give more informations if you want your problem to be solved.