🥛 Milk Scanner

• 🐱 github

A 3D scanner using a tray of milk. I can’t find the link right now but it wasn’t the first, and I can’t remember if it was an independent invention or not.

The setup looks like this:

Ingredients

• A makeshift light box using a desk lamp (stolen from my mum), a coat hanger, tape and a sheet of A4 paper. Taped to one of Katherine’s footstools.
• A tin can with a hole punched in one side, and a curly straw blu-tacked into the hole to pour the milk into the tray. The can probably contained soup.
• A tray that I guess had some kind of stationary in it.
• Kath’s compact camera and tripod, the camera did video.
• A volunteer ornament stolen from my mum, probably from a visit to Auntie Carol and Uncle Steve’s.
• A bottle of whatever that is. If it was any good it’d be empty.

Method

So you pop your item in the dish, point the camera at it, and record a video of it gradually submerging into the milk:

⏯

Take the output and run it through an edge detection filter, then this program

This looks at each pixel and records when it turned white. The longer it takes, the closer to the surface it is. Divide by the total time, and you have a depth map that can be used to reconstruct the surface.

Join with the diffuse channel, you’ve got a texture map with depth, that can be converted into a normal map or tessellated into a mesh:

Notes

SFM techniques made this approach worthless, but it’s still pretty cool. I did try a different approach using a laser but never finished that, similar way to how book scanners flatten pages.

Here’s a link to another one that someone made 7 years later.