Printing Anisotropic Appearance with Magnetic Flakes

ACM Trans. Graphics, July 2017

Thiago Pereira, Carolina L. A. Paes Leme,
Steve Marschner, Szymon Rusinkiewicz

Left: Our setup consists of a DLP projector modified to project UV light, a focusing lens, and five electromagnets surrounding a target (not visible) coated with magnetic flakes in a UV-curable resin. Center: We use the electromagnets to orient the flakes in three configurations, then solidify the resin in particular spatial patterns. Right: Observing the surface under different illumination directions, we see that it exhibits spatially-varying reflectance.

The ability to fabricate surfaces with fine control over bidirectional reflectance (BRDF) is a long-standing goal in appearance research, with applications in product design and manufacturing. We propose a technique that embeds magnetic flakes in a photo-cured resin, allowing the orientation distribution of those flakes to be controlled at printing time using a magnetic field. We show that time-varying magnetic fields allow us to control off-specular lobe direction, anisotropy, and lobe width, while using multiple spatial masks displayed by a UV projector allows for spatial variation. We demonstrate optical effects including bump maps: flat surfaces with spatially-varying specular lobe direction.

PDF file

Thiago Pereira, Carolina L. A. Paes Leme, Steve Marschner, and Szymon Rusinkiewicz.
"Printing Anisotropic Appearance with Magnetic Flakes."
ACM Trans. Graphics 36(4):123, July 2017.

@article{Pereira:2017:PAA,
   author = "Thiago Pereira and Carolina L. A. Paes Leme and Steve Marschner and
      Szymon Rusinkiewicz",
   title = "Printing Anisotropic Appearance with Magnetic Flakes",
   journal = "ACM Trans. Graphics",
   year = "2017",
   month = jul,
   volume = "36",
   number = "4",
   pages = "123"
}