5 ms·

What I don't get is why this isn't easy to do with a smartphone. A little motorized turntable with a stand for your phone and a calibration object covered in tr

What I don't get is why this isn't easy to do with a smartphone. A little motorized turntable with a stand for your phone and a calibration object covered in tracking symbols to use for adjusting the input from the camera. Why is that so impossible?

mdaniel 6y ago
I don't have expertise in this area, but my experience with other engineering disciplines is that nothing is ever as easy in practice as it is in words, because there are a lot of things that can go wrong or not be compatible with one another "The devil is in the details" and "talk is cheap" are common expressions for a reason
- rrmm 6y ago
  Basically, lens imperfections, camera noise, vibration and lack of rigid setups (and a hefty dose of etc.).
errantspark 6y ago
It's easy to do with a smartphone and you usually don't even need a calibration object. A software like Metashape or Meshroom can infer the lens transform and position of the camera from enough photos of the same object from different angles. The small smartphone optics actually help you by giving you a deeper DoF. Not the best example but this http://koanlabs.org/vignettes.html http://koanlabs.org/vignettes.html rock is ~5 cm tall and my best guess is the minimum detectable feature size is about 10 microns. EDIT: Sorry to be clear the definition of easy here is "as easy as most photogrammetry", to get good results you will universally do a lot of knob twiddling, waiting and cleaning up broken bits of mesh unless all you do is scan rocks. Scanning rocks is easy.
yarcob 6y ago
A few years back I tried an iPhone app (123D Catch from Autodesk) that allowed creating 3D models just by manually moving the phone around an object. No turntable or stand needed. It worked surprisingly well, but was unfortunately discontinued. Since it was cloud based the app no longer works :( I wonder if there are any similar apps available now?
thomas_OpenScan 6y ago
Actually, this is how I started the project. See for instance this one here (OpenScan in 2019 https://www.instagram.com/p/Bt6JtjEoEM7/ https://www.instagram.com/p/Bt6JtjEoEM7/) But I have found that smartphones give very inconsistent results (probably due to image"improving" algorithms...), see https://www.instagram.com/p/B1q1syMoHfG/ https://www.instagram.com/p/B1q1syMoHfG/ So I moved on to the raspberry pi + camera, which is much easier and better to control as you need very, very consistent images...
- Causality1 6y ago
  Interesting. What's the materials cost for the pi-based setup?
  - thomas_OpenScan 6y ago
    100-200€ plus the printed parts (~50€). But most people diy some or even all parts for even less

mdaniel 6y ago

I don't have expertise in this area, but my experience with other engineering disciplines is that nothing is ever as easy in practice as it is in words, because there are a lot of things that can go wrong or not be compatible with one another "The devil is in the details" and "talk is cheap" are common expressions for a reason

rrmm 6y ago
Basically, lens imperfections, camera noise, vibration and lack of rigid setups (and a hefty dose of etc.).

errantspark 6y ago

It's easy to do with a smartphone and you usually don't even need a calibration object. A software like Metashape or Meshroom can infer the lens transform and position of the camera from enough photos of the same object from different angles. The small smartphone optics actually help you by giving you a deeper DoF. Not the best example but this http://koanlabs.org/vignettes.html http://koanlabs.org/vignettes.html rock is ~5 cm tall and my best guess is the minimum detectable feature size is about 10 microns. EDIT: Sorry to be clear the definition of easy here is "as easy as most photogrammetry", to get good results you will universally do a lot of knob twiddling, waiting and cleaning up broken bits of mesh unless all you do is scan rocks. Scanning rocks is easy.

yarcob 6y ago

A few years back I tried an iPhone app (123D Catch from Autodesk) that allowed creating 3D models just by manually moving the phone around an object. No turntable or stand needed. It worked surprisingly well, but was unfortunately discontinued. Since it was cloud based the app no longer works :( I wonder if there are any similar apps available now?

thomas_OpenScan 6y ago

Actually, this is how I started the project. See for instance this one here (OpenScan in 2019 https://www.instagram.com/p/Bt6JtjEoEM7/ https://www.instagram.com/p/Bt6JtjEoEM7/) But I have found that smartphones give very inconsistent results (probably due to image"improving" algorithms...), see https://www.instagram.com/p/B1q1syMoHfG/ https://www.instagram.com/p/B1q1syMoHfG/ So I moved on to the raspberry pi + camera, which is much easier and better to control as you need very, very consistent images...

Causality1 6y ago
Interesting. What's the materials cost for the pi-based setup?
- thomas_OpenScan 6y ago
  100-200€ plus the printed parts (~50€). But most people diy some or even all parts for even less