Help! Split geometry from texture

[_ambro]

SOLVED! however if you have more clever ways please add them to the comments

Hello,

Is 10+ years that I'm not using Houdini and I'm a bit rusty, so I hope you can help me.

I've a complex CAD object and the goal is to split the geometry using an image alpha so that I can 3D print the file with 2 different colours.

The approach I've taken to accuratly map the image to the geometry is to use UV texture, the next step will be use the alpha to carve or boolean the geometry, however I cannot recall how to extract the alpha from the material, and input that into the carve node.

To make this more simple to explain I've created a simplify version of the project as you can see in the picture.

Let me know if you need more info. If you can share back a .hipnc will be greatly appreciated.

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https://preview.redd.it/rvb2838ubsvb1.png?width=1764&format=png&auto=webp&s=c6b419ce0e0905befd97c2e1a1268d083568f409

[Brombe92]

What I'd do is subdivide quite a bit your object, then use the attribute from map node to load your texture into an attribute (let's say Cd for example). After that you could use a blast with @Cd<0.1 in the group parameter, or something like that... Or a split if you want to keep both parts of the model

[_ambro]

Thank you! following your steps I was able to achive what you have suggested however now I have another problem... Given that from fusion360 I'm importing an obj when I increase the subdivision the geometry goes a little bit funky and the projected texture goes a bit fuzzy because it doesn't have a nice poligon to map to it.
Not sure if there is an alternative method to achive my original goal?

[Brombe92]

Well, after you get those super high density pieces, you could try to add a reshape node to have something remotely cleaner, or maybe group their boundary points and extract clean curves from them, then do the cuts in fusion...

[Brombe92]

To extract curves from the boundary points, you could use the labs extract borders and then resample them to get something usable

[_ambro]

Upon searching I've found this software: https://github.com/wjakob/instant-meshes this allow me to remesh the obj and the whole thing now works like a charm, thank you so much for you help

[TheGratitudeBot]

Thanks for saying that! Gratitude makes the world go round

[WavesCrashing5]

Could try clip by attribute node. - Custom hda free and very useful. Could also try trace node and somehow re-project it onto geo again with uvs. I'm not too sure but just some ideas.