Microfacet Billboarding for Image-based Rendering

Rendering of intricately shaped objects that are soft or cluttered is difficult because we cannot accurately acquire their complete geometry. Since their geometry varies drastically, modeling them using fixed facets can lead to severe artifacts when viewed from singular directions. We propose a novel modeling method, microfacet billboarding, which uses view-dependent microfacets with view-dependent textures. The facets discretely approximate the geometry of the object and are aligned perpendicular to the viewing direction. The texture of each facet is selected from the most suitable texture images according to the viewpoint. Microfacet billboarding can render intricate geometry from various viewpoints. We have also implemented a real-time renderer by a hardware-accelerated technique.

Publications

PDF
Shuntaro Yamazaki, Ryusuke Sagawa, Hiroshi Kawasaki, Katsushi Ikeuchi and Masao Sakauchi,
Microfacet Billboarding”,
In Proc. the 13th Eurographics Workshop on Rendering, pp.169-179, vol.13,
June, 2002
PDF
Shuntaro Yamazaki, Ryusuke Sagawa, Hiroshi Kawasaki, Katsushi Ikeuchi and Masao Sakauchi,
Rendering intricately-shaped objects using view-dependent microfacets”,
IEICE Transactions on Information and Systems D-II, vol.J86-D-II, no.10, pp.1441-1449, (Japanese)
October 2003
PDF
Shuntaro Yamazaki, Katsushi Ikeuchi,
Photo-realistic Rendering of Real-world Objects Based on Insufficient Measurement”,
IPSJ Journal of Computer Vision and Image Media, no.11, (Japanese)
June 2005

Supplementary Material

Demo video

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Concept of Microfacet Billboarding

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Modeling intricate shapes using polygons is problematic particularly on occluding boundaries. View-dependent microfacet is an approximation of surface geometry. When view point changes, the facet rotates and is kept perpendicular to the viewing direction.

Captured Range Image and Camera View

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A set of range images is converted to a volumetric representation using signed distance transformation and integrated into a single volume, which in turn is used as a coarse approximation of the oject shape.

Merged Volume

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This is the volume data visualized by the technique of volume rending with red and yellow colors for the voxels outside and inside the surface.

Microfacet

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A microfacet is defined as a slice which intersects the voxel and is aligned perpendicular to the viewing direction with a constant interval.

Rendering by Microfacet Billboarding

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Level-Of-Detail Control

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The number of microfacets is changed depending on the size of the object on a rendering screen to optimize the speed and quality of rendering.

Miscellaneous