A 3D Scanner That Archimedes Could Get Behind

3D-scanning seems like a straightforward process — put the subject inside a motion control gantry, bounce light off the surface, measure the reflections, and do some math to reconstruct the shape in three dimensions. But traditional 3D-scanning isn’t good for subjects with complex topologies and lots of nooks and crannies that light can’t get to. Which is why volumetric 3D-scanning could become an important tool someday.

As the name implies, volumetric scanning relies on measuring the change in volume of a medium as an object is moved through it. In the case of [Kfir Aberman] and [Oren Katzir]’s “dip scanning” method, the medium is a tank of water whose level is measured to a high precision with a float sensor. The object to be scanned is dipped slowly into the water by a robot as data is gathered. The robot removes the object, changes the orientation, and dips again. Dipping is repeated until enough data has been collected to run through a transformation algorithm that can reconstruct the shape of the object. Anywhere the water can reach can be scanned, and the video below shows how good the results can be with enough data. Full details are available in the PDF of their paper.

While optical 3D-scanning with the standard turntable and laser configuration will probably be around for a while, dip scanning seems like a powerful method for getting topological data using really simple equipment.

Thanks to [bmsleight] for the tip.

Decorate Your 3D Prints With Detailed Hydrographic Printing

It’s like the old quip from [Henry Ford]: You can have your 3D prints in any color you want, as long as it’s one. Some strides have been made to bringing more color to your extruded goodies, but for anything beyond a few colors, you’re going to need to look at post-print processing of some sort. For photorealistic 3D prints, you might want to look into a simple hydrographic printing method that can be performed right on a printer.

If some of the prints in the video below look familiar, it’s because we covered the original method when it was presented at SIGGRAPH 2015. [Amos Dudley] was intrigued enough by the method, which uses computational modeling of complex surfaces to compose a distorted image that will be stretched back into shape when the object is dipped, to contact the original authors for permission to use the software. He got a resounding, “Nope!” – it appears that the authors’ institution isn’t big into sharing information. So, [Amos] hacked the method.

In place of the original software, [Amos] used Blender to simulate the hydrographic film as a piece of cloth interacting with the 3D-printed surface. This allowed him to print an image on PVA film that will “un-distort” as the object is dipped. He built a simple tank with overflow for the printer bed, used the Z-axis to dip the print, and viola! Photo-realistic frogs and globes.

[Amos]’ method has its limitations, but the results are pretty satisfying already. With a little more tweaking, we’re sure he’ll get to the point that the original authors did, and without their help, thank you very much.

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