New methods for the computational fabrication of appearance

Abstract:

3D printing has been advancing rapidly with new machines becoming available each
year. They can already accurately reproduce an object’s shape. However, they are
very limited when reproducing the object’s appearance. Computational fabrication of
appearance is an interesting research direction which seeks to extend the appearance
reproduction capabilities of current devices and also to manage their limitations. It
can have great impact in a number of di↵erent fields including product prototyping
and design, realistic prosthesis and watermarks in security. This thesis presents
three appearance fabrication works: a similarity metric, a light routing algorithm and
reflectance fabrication process.
First, recent spatially varying reflectance (svBRDF) printing systems can reproduce
an input document as a combination of matte, glossy and metallic inks. Due
to the limited number of inks, this reproduction process incurs some distortion. To
preserve a material’s perceived variation with lighting and view, we introduce an
improved BRDF similarity metric that builds on both experimental results on reflectance
perception and on the statistics of natural lighting environments. We validate
it quantitatively as well as through a perceptual study. We also show how to
adapt traditional color gamut mapping methods to svBRDFs to preserve textures
and edges.
Second, we use multi-material 3D printing to fabricate objects with embedded
optical fibers, exploiting total internal reflection to guide light inside an object. We
introduce automatic fiber design algorithms together with new manufacturing techniques
to route light between two arbitrary surfaces. Our implicit algorithm optimizes
light transmission by minimizing fiber curvature and maximizing fiber separation
while respecting manufacturing constraints. Our methods enables new applications
in sensing and display such as surface displays of arbitrary shape.
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