Printing Gaussian splats: from a scanned bee to a crystal-like 3D print

3D graphics developer Dany Bittel has described what happened when one of his Gaussian splat scans — an insect, later referred to as a bee — was turned into a physical object. The print was made by the company Crysta AI, after its founder Teng Xu contacted him and offered to print one of his insects as a present.

Preparing a splat for print

Gaussian splatting captures a scene as a cloud of 3D blobs, but a printed object cannot show view-dependent colour. Bittel therefore trained the splat directly with spherical harmonics at level 0 instead of averaging that information afterwards. He also trained it in linear space, hoping to obtain more physically plausible transparency values. In hindsight he is unsure whether that was a good idea, because Crysta had to adjust their pipeline to handle his file.

On Crysta's side, the Gaussian splat is first voxelised, a bit like a Minecraft level: each voxel holds a mixture of inks and can be more or less transparent. That voxel grid is then printed layer by layer on a Stratasys PolyJet J850 Prime, a machine that deposits droplets of material and supports transparent and multi-material builds.

What the print looks like

The result is a piece of "crystal" that Bittel describes as a modern version of amber, material that could trap an object for eternity. His own print, he says, came out a little too brown and dark — possibly a consequence of the linear file — and he still sees some splat artefacts in it. The colour, however, may be quite accurate. The fine fur remains a little too clumpy or thick, since transparency at that scale is hard to reproduce. Shining a light through the bee produced an unexpected effect: the internal structures become visible, almost as if its organs were showing through.

What comes next

Crysta AI is still building its business and has recently released an alpha version of an editor for placing and scaling a splat. Bittel suggests two additions: a way to preview the voxelisation before printing, and support for importing voxel data — anything modelled in MagicaVoxel, for example — which would open the service to more artists. He would also like to import splats into MagicaVoxel. More example prints are shown on the company's X account.