Abstract
We consider the design of an inexpensive system for acquiring material models for computer graphics rendering
applications in animation, games and conceptual design. To be useful in these applications a system must be able
to model a rich range of appearances in a computationally tractable form. The range of appearance of interest in
computer graphics includes materials that have spatially varying properties, directionality, small-scale geometric
structure, and subsurface scattering. To be computationally tractable, material models for graphics must be
compact, editable, and efficient to numerically evaluate for ray tracing importance sampling. To construct
appropriate models for a range of interesting materials, we take the approach of separating out directly and
indirectly scattered light using high spatial frequency patterns introduced by Nayar et al. in 2006. To acquire
the data at low cost, we use a set of Raspberry Pi computers and cameras clamped to miniature projectors.
We explore techniques to separate out surface and subsurface indirect lighting. This separation would allow
the fitting of simple, and so tractable, analytical models to features of the appearance model. The goal of the
system is to provide models for physically accurate renderings that are visually equivalent to viewing the original
physical materials.
