Generalized Image Acquisition and Analysis

Volume Stylizer: Tomography-based Volume Painting

Volumetric phenomena are an integral part of standard rendering, yet, no suitable tools to edit characteristic properties are available so far. Either simulation results are used directly, or modifications are high-level, e.g., noise functions to influence appearance. Intuitive artistic control is not possible. We propose a solution to stylize single-scattering volumetric effects. Emission, scattering and extinction become amenable to artistic control while preserving a smooth and coherent appearance when changing the viewpoint. Our approach lets the user define a number of target views to be matched when observing the volume from this perspective. Via an analysis of the volumetric rendering equation, we can show how to link this problem to tomographic reconstruction.


Acquisition and Analysis of Bispectral Bidirectional Reflectance and Reradiation Distribution Functions

Matthias Hullin, Johannes Hanika, Boris Ajdin, Hans-Peter Seidel, Jan Kautz, Hendrik P. A. Lensch
In: Proceedings of SIGGRAPH 2010.


In fluorescent materials, light from a certain band of incident wavelengths is reradiated at longer wavelengths, i.e., with a reduced per-photon energy. While fluorescent materials are common in everyday life, they have received little attention in computer graphics. Especially, no bidirectional reradiation measurements of fluorescent materials have been available so far. In this paper, we extend the well-known concept of the bidirectional reflectance distribution function (BRDF) to account for energy transfer between wavelengths, resulting in a Bispectral Bidirectional Reflectance and Reradiation Distribution Function (bispectral BRRDF). Using a bidirectional and bispectral measurement setup, we acquire reflectance and reradiation data of a variety of fluorescent materials, including vehicle paints, paper and fabric, and compare their renderings with RGB, RGB×RGB, and spectral BRDFs. Our acquisition is guided by a principal component analysis on complete bispectral data taken under a sparse set of angles. We show that in order to faithfully reproduce the full bispectral information for all other angles, only a very small number of wavelength pairs needs to be measured at a high angular resolution.


title={{Acquisition and analysis of bispectral bidirectional reflectance and reradiation distribution functions}},
author={Hullin, M.B. and Hanika, J. and Ajdin, B. and Seidel, H.P. and Kautz, J. and Lensch, H.},
journal={ACM Transactions on Graphics (TOG)},
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