Automated acquisition and real-time rendering of spatially varying optical material behavior

Abstract

Photorealism in 3D rendering is expanding across different fields of applications, including 3D games industry and rapid prototyping in many domains already in early design stages, e.g. in the automotive and textile industry. But where do the specifications come from that define realistic materials? Manual design of material models has been perfected over a long time to deliver quite good results. The only way, however, to bring out the physically correct light interaction behavior for each individual (or mixture of different) material(s) on a surface, is actual measurement under systematic illumination from a set of different perspectives to reveal the actual optical reaction. One reason to go this far is material behavior faithful to reality, and individual rather than defining abstract classes of materials. Another reason is damage assessment, e.g. for industrial quality control.

Seamless and non-repetitive 4D texture variation synthesis and real-time rendering for measured optical material behavior

“…3D rendering research is continuously striving to come closer to a physically realistic representation of realworld surfaces, as it is ever more widely applied to fields where a high degree of realism is required (e.g., the 3D games industry) or where rapid prototyping is applied in early stages of design (e.g., in the automotive and textile industries). The approach of measuring ABTFs (approximate bi-directional texturing functions) [1,2] is one way to avoid the need for synthetic design of material models, as it used to be the standard for a long time even though requiring significant manual effort. ABTFs were first proposed by Ref.…”

“…Thus, an additional dimension of incoming light direction was added in Ref. [2]. By using a turntable which rotates the sample around its surface normal under the camera, 4D ABTF model results from combining the two lateral dimensions with two angular dimensions describing the hemisphere of incident light directions.…”

“…The ABTF material model acquired and rendered with the technique in Ref. [2] represents actually captured real-world material behavior as a 4D texture that can be rendered in real time. By only considering one perspective vertically above the sample, it provides an abstraction of the higher dimensional 6D BTF (bidirectional texturing function) [3] that captures the spatially varying material behavior of flat materials, discretized to the resolution of a matrix sensor (2D), for all combinations of incoming light (2D) and outgoing observer direction (2D), while preserving the dependence on the incoming light direction.…”