Drag knife✒️ and Laser🔫 Etched (Specular) Holograms

That could also help with occlusion.

You would basically ray trace a bunch if points from different angles. If the point was visible from multiple angles, you could connect where those rays intersected with the surface to form the arc. If there were angles where the points were not visible, you could just lift the pen there to create occlusion.

The trade off is that it is more computationally intense. But even if it took a few minutes (which it shouldn’t), it would be fine.

The user would have to supply a 3D model and choose a texture to map. The program could use that to generate an svg or toolpath.

Makes sense to me. It seems solved, so I’m no longer obsessing over it. I’ve lost interest :slight_smile:.

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Also, what the heck is this thing?

I can’t figure out what that is supposed to be doing.

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Why would you make holograms with speculums? Wait, wrong forum…

That could also help with occlusion.

Matt Brand only rotates the object a limited amount. A person could select the points visible half way through the rotation, and ignore occlusions. Or, if a person wanted to deal with it, simply save the normal of the triangle from the STL where the point lives, and eliminate any points on the arc where projection of the normal does not intersect the viewing plane.

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You wouldn’t have to do that, right? If the point on the texture was blocked by another part of the model, the ray wouldn’t reach it, so you would know to stop the path.

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Some info and resources I stumbled across on Steve Mould’s discord channel and elsewhere while digging into this, including scratchhologram C# code that can load .x3d files, simulate and generate arcs on the view plane…

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OOOOOHHHHH! Who’s gonna try it!?!

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What’s cheapest drag bit you’d try? amzn Diamond spring drag bits seem surprisingly spendy.

2023-02-21 23-54-24_scratch-hologram-preview

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That’s the one i use. I couldn’t really find one cheaper that looked like it worked well. This one did a great job for me on the big acrylic sign i did.

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How many arc segments is that? That seems like a lot. That is so crazy though, I love how things “hide” behind others. Just crazy.

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Lots. Can tune number of points/arcs, GIF shows rough milling time estimates. Guaranteed to be slow. Waiting on diamond bit, sunk enough time into tuning/extending app to rationalize the cost.

2023-02-21 23-54-24_scratch-hologram-vectors

Currently trying to figure out way to remove lines/edges on the same face, have an idea (don’t render edges shared by adjacent faces on the same plane, maybe…). My math isn’t great, and it’s been a while since I coded 3D geometry rendering… Fortunately Mike Miller did all the hard stuff already.

Coded up simple G2 circular arc based script for now. Haven’t looked into tweaking elliptical arcs to reduce distortion, haven’t verified/implemented occlusion. Will share fork if my edits seem more useful than harmful for someone else to use.

2023/2/22 Edit: Model is easier to discern by hiding edges between faces on the same plane. Less arcs, noise and mill time. Fancy drag bit arrived, testing on cheapo bits first…

2023/2/23 Edit: No physical testing yet. Still improving functionality/performance, e.g. arcs for hidden edges/points were mistakenly being drawn. Currently figuring out partial arc segments so occlusion works when changing view angle.

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I am amazed. Cool.

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Hi, can you export SVG or DXF? I can engrave it with laser and i have couple of different methods and styles that can help in evolution of this effects.

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I don’t think a laser would work, It doesn’t leave a shiny scratch, and I would think the mark it would make would be too large.

Are you sure ? Because i know what I’m telling :sweat_smile:
Here couple examples of my works on Instagram @rokolart.lviv
And here some gif

ac66b0aa-adef-4380-9e5c-e281208be422

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I found a lot of effects, so I think it’s be useful for you to understand what possibilities there.
c5f89de8-c611-4c1c-b4b2-b00759bf05c7

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I didn’t even think about metal. That would be nice! Please share an example when you get it working!

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Hello @Ic_In, welcome! You’re creating beautiful work pieces on https://www.instagram.com/rokolart.lviv/. Just posted a reference to this forum on Steve Mould’s Discord incase others are interested.

The things you’re doing with laser etching look like sorcery to me. We have a bunch of laser folks here too. Look forward to learning how you guys are lasering color finishes from their metal stock?

Not yet, but maybe, SVG should be very doable (have written code to generate that before), will take a look if I can figure out occlusion, and speed things up.

I reached out to Mike Miller via github to thank him for sharing the project, and let him know it’s being tinkered with here.

Will keep sharing occasional updates partly for anyone who’s interested, but also partly to help discover if others have done this already (so I don’t need to :slight_smile: ), and/or discover interesting related work out there. Cheers!

Nice additions to the original program! I’d love to take a look at your fork, and use the gcode export to do some practical testing on a few different materials i’ve ordered, if you’re able to publish it.

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I’m also trying to make some research with rhino7 grasshopper to generate geometry easy, but looks like it takes too long, so will be happy to see your examples and test them.

Thanks for your time. Cheers

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