Comments on: Milkscanner – 3D mapping that’s good for you

By: flug

flug — Mon, 06 Aug 2007 17:05:32 +0000

coolest 3d scanner i`ve ever seen. great!

Does anyone know the name of the song?

By: Eric

Eric — Sun, 10 Jun 2007 20:16:48 +0000

Unless I'm misunderstanding the method here, it seems it will only accurately scan objects that narrow as you move up the Y-axis because otherwise the object's width would be blocking the camera's view.

If this were a profile view(the webcam would still be viewing from the top), the webcam wouldn't see anything below the widest point of the object.
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This of course could be solved by scanning one side and then the other but would still leave some objects unscannable. Good for what it is though.

By: JulesD

JulesD — Fri, 08 Jun 2007 03:25:11 +0000

Very good... I like it!

But here are other less messy ways as well, that turn out good results.... One of them is the free laser scanning software DAVID.....

Check out some tests I did for a rig that cost me Â£15.50 for my first scans...

http://www.blog.global6.net/julesd/index.php?/categories/7-DAVID-scans

J

By: Smurfsahoy

Smurfsahoy — Thu, 07 Jun 2007 07:49:16 +0000

To fix the issue of surface tension with the diagonal bar, just add alcohol to the milk to break the tension (a white russian scanner?) Or perhaps float a thin layer of oil on top (the oil will stay in place, since with the bar, you don’t have to let the milk overflow anymore).

By: Reader

Reader — Thu, 07 Jun 2007 07:38:28 +0000

Coolest hack I’ve seen on any site for a long time, I might be tempted to do this!

By: Matt

Matt — Thu, 07 Jun 2007 06:48:15 +0000

The trouble with this is that it’s using a webcam, which means the images it captures are in perspective. That’s okay for small objects where accuracy isn’t that necessary (as shown), but I wouldn’t use it for any precision work.

If you can manage to get a scanner head to take focused images a few inches away, then you’d really have something.

By: andrew

andrew — Thu, 07 Jun 2007 06:22:59 +0000

the song on the vid reminds me of drinking milk…. mmmm… :)

By: Drew

Drew — Thu, 07 Jun 2007 04:03:04 +0000

Now this is a sweet hack. Is there someway this method could create a 3D CAD file for the scanned object? I’ve been working on a project that would need metal parts machined to the contours of my head, and this would solve my dillema if I could create an accurate 3D CAD file for my head. Any thoughts?

By: MacGyverS2000

MacGyverS2000 — Thu, 07 Jun 2007 03:09:03 +0000

@ hello1024:
The 45 degree bar method isn't as simple a it first appears. For large increases in depth (e.g., 2mm steps), no problem. Once you start getting into the smaller steps (e.g., 0.5mm and so on), you're going to run into problems with surface tension and the milk's meniscus. You may have to increase the level several times before surface tension gives in and allows the milk to change location on the level.

By: sinerasis

sinerasis — Wed, 06 Jun 2007 22:13:15 +0000

way cool, nice work

By: DarkFader

DarkFader — Wed, 06 Jun 2007 22:02:43 +0000

Very nice. Any way to do this with plain water? Perhaps with a different colored lights or something and a piezo element to make the water reflect all lamps? Then take a continuous video while it’s filling up and then post-process.

By: Blind Tree Frog

Blind Tree Frog — Wed, 06 Jun 2007 20:46:58 +0000

>> Post 13 (loebas)
"that wont make it go linear. where the object is wide, the milk will rise a bit due to more milk displacement. it would have to be combined with a diagonal ruler, or some sort of floating device. (like the ones in toilet flushers)"

At which point the milk will overflow over the edge of the container (like I stated) and the level of the milk will stay at the same exact level every single time.

By: Loebas

Loebas — Wed, 06 Jun 2007 19:33:54 +0000

that wont make it go linear. where the object is wide, the milk will rise a bit due to more milk displacement. it would have to be combined with a diagonal ruler, or some sort of floating device. (like the ones in toilet flushers)

By: Blind Tree Frog

Blind Tree Frog — Wed, 06 Jun 2007 18:08:15 +0000

Combining comments at the link the best idea I've heard mentioned is using an overflow style of tank (so the milk is at the top and overflows as the object lowers) with a shelf that the object sits on and lowers down into the tank automatically.

The milk then stays at the same level (because you just keep the tank full to the rim at all times) and you don't have to adjust for the milk getting closer or further from the lens.

By: Hello1024

Hello1024 — Wed, 06 Jun 2007 16:28:13 +0000

You could easily measure the milk level with some kind of bar at 45 degrees to the vertical in the cameras field of view. By measuring the length of the bar that's visible to the camera, you can calculate depth.

Using this method, the system could be made easier very quickly by starting with the container full, and putting a small hole+cork in the bottom to let the milk drain out. As it drains, you constantly measure the depth and take readings at intervals of say 0.5mm, giving a much better resoloution. The wet and therefore reflective object being scanned may give holes in the model though, so it might be better to have the milk draining in from another higher up container.

A way to improve the accuracy would be to consider parallax, by adding in some trig calculations to the program, and then have multiple cameras in different places, using those calculations to allow "overhanging" bits of the model to be picked up.

Also, by using say a uv ink and uv light instead of the milk would allow you to easily scan items which are too white to programaticly discern with milk.