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Show HN: 3dasd – open-source DIY room-scale 3D scanner

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Re: Show HN: 3dasd – open-source DIY room-scale 3D scanner

#31

Post by dannyw »

bruce343434 wrote: post #23

This is really cool. I'm looking to build a body scanner so I can import a 3d model of my body. I can then use this model in Marvelous Designer to make shirts and pants and other clothes that will literally fit perfectly to my body. I'm thinking of a platform on which you stand, with a rotating arm under it which holds the arduino which then scans up and down, the arduino relays the distance and both angles to a proc…

Ask HN: If I have a budget of maybe ~$1000, what would be the best body scanner I can get? Happy with either DIY or for-purchase.

Keen to try some ML projects with a body-sized scanner.

Re: Show HN: 3dasd – open-source DIY room-scale 3D scanner

#32

Post by sbayeta »

dvoros wrote: post #2

Taking a break from my software developer job, I've started to work on my first ever hardware project and with too much free time on my hands it quickly turned into something bigger than I've anticipated. Working with a friend, we wanted to explore the use of 3D scanners on construction sites but quickly got stuck as no cheap hardware was available to fool around with. How hard can it be to build one I thought? I've…

Congrats! Seems like a neat project. I just skimmed through the article and saw "it tries to be cheap". Maybe you can evaluate whether ultra-cheap steppers can give you acceptable results. They cost around 1/10 compared to the kind you're using. They are a lot slower and have less torque, but probably could give similar results.

Good luck and thanks for sharing this!

Re: Show HN: 3dasd – open-source DIY room-scale 3D scanner

#33

Post by sbayeta »

sbayeta wrote: post #32
dvoros wrote: post #2

Taking a break from my software developer job, I've started to work on my first ever hardware project and with too much free time on my hands it quickly turned into something bigger than I've anticipated. Working with a friend, we wanted to explore the use of 3D scanners on construction sites but quickly got stuck as no cheap hardware was available to fool around with. How hard can it be to build one I thought? I've…

Congrats! Seems like a neat project. I just skimmed through the article and saw "it tries to be cheap". Maybe you can evaluate whether ultra-cheap steppers can give you acceptable results. They cost around 1/10 compared to the kind you're using. They are a lot slower and have less torque, but probably could give similar results. Good luck and thanks for sharing this!

Sorry forgot to mention I'm thinking specifically of the 28byj-48 motors. I had an (unfinished) project making a motorized water sprinkler for watering lawns in non circular shapes, and these motors were up to the task. If you can achieve your goal with them, you'll probably shave a nice chunk of the cost (not only on the motors but also on the drivers). Cheers

Re: Show HN: 3dasd – open-source DIY room-scale 3D scanner

#37

Post by dekhn »

encypruon wrote: post #30
dvoros wrote: post #2

Taking a break from my software developer job, I've started to work on my first ever hardware project and with too much free time on my hands it quickly turned into something bigger than I've anticipated. Working with a friend, we wanted to explore the use of 3D scanners on construction sites but quickly got stuck as no cheap hardware was available to fool around with. How hard can it be to build one I thought? I've…

Great project and excellent presentation! I've been trying to build something similar for tracking birds / panoramas / photogrammetry while avoiding using non-printed parts as much as possible but haven't been very successful so far. Because of that I'm particularly interested in the printed gears you are using. Maybe you could help me with some of my questions and concerns. It looks like the whole thing is designed…

if you really care about backlash, just measure it and then add a correction in your motor controller.

Another way to do this is to always move back to endstop zero, and only move forward. THis is very limiting.

The biggest problem I had was all my PLA prints melted in the direct sun!

Re: Show HN: 3dasd – open-source DIY room-scale 3D scanner

#38

Post by dekhn »

PicassoCTs wrote: post #17
rambojazz wrote: post #8

I'm not familiar with the 3d scanning tech, but my first thought when looking at the examples is that they do not look really detailed. What is the max "resolution" of the machine? Can it scan objects with a higher number of particles?

Max resolution are the steps of the stepper motor per activation. (1.8° step-angle) https://datasheetspdf.com/pdf/1260602/Schneider/NEMA17/1 It could be increased by adding multiple distance measurement sensors in parallel per scan direction. It could also be made more precise by adding a "sub-gear" that only turns within the frame of the step. But this would lengthen the scan process considerably. To shorten that ag…

Stepper motors can be microstepped (typically up to 1/32 or 1/64). In my experience, this works poorly as the microsteps are not evenly spaced. I find gearing works better.

Re: Show HN: 3dasd – open-source DIY room-scale 3D scanner

#39

Post by dekhn »

ur-whale wrote: post #24

How does this improve on taking a video with your phone and feeding it to one of the OpenSource 3D reconstruction packages (such as e.g. MeshRoom [1])? [1] https://alicevision.org/#meshroom

I don't think it helps meshroom much because (afaict) there's no easy way to tell meshroom the angular information that's known from the stepper controller (I couldn't find anything obvious in the docs). If that worked, you could avoid the expensive and error prone initial orientation-determining step, which is absurdly slow.

I've done similar to this article but using Hugin as a panorama constructor. It speeds up the process signnificantly (because again you don't have to search for image orientations if you "know" them).

Re: Show HN: 3dasd – open-source DIY room-scale 3D scanner

#40

Post by encypruon »

dekhn wrote: post #37
encypruon wrote: post #30

Earlier quoted context omitted.

Great project and excellent presentation! I've been trying to build something similar for tracking birds / panoramas / photogrammetry while avoiding using non-printed parts as much as possible but haven't been very successful so far. Because of that I'm particularly interested in the printed gears you are using. Maybe you could help me with some of my questions and concerns. It looks like the whole thing is designed…

if you really care about backlash, just measure it and then add a correction in your motor controller. Another way to do this is to always move back to endstop zero, and only move forward. THis is very limiting. The biggest problem I had was all my PLA prints melted in the direct sun!

> if you really care about backlash

At 1200 mm equivalent a picture is only about 1.15° high, so accuracy is important :)

> just measure it and then add a correction in your motor controller.

I think your first idea doesn't really work for tilting because there is little friction and the camera isn't going to be perfectly balanced (the center of gravity also changes with the focal length and even the focus). When gravity pulls the camera towards one direction backlash is less of a problem, but when it's near the tipping point it becomes really shaky and sensitive to disturbances. Past the tipping point it is biased towards the other direction.

Preloading might be an easy fix but at the cost of acceleration.

> Another way to do this is to always move back to endstop zero, and only move forward. THis is very limiting.

At least for panning in panoramas this isn't a bad solution at all. I think both your ideas are good for panning with planned paths.

> The biggest problem I had was all my PLA prints melted in the direct sun!

Was it white PLA? So far I've only had stuff bend out of shape in the car.

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