Generalized Image Acquisition and Analysis

Time-resolved 3D Capture of Non-stationary Gas Flows

Fluid simulation is one of the most active research areas in computer graphics. However, it remains difficult to obtain measurements of real fluid flows for validation of the simulated data. In this paper, we take a step in the direction of capturing flow data for such purposes. Specifically, we present the first time-resolved Schlieren tomography system for capturing full 3D, non-stationary gas flows on a dense volumetric grid. Schlieren tomography uses 2D ray deflection measurements to reconstruct a time-varying grid of 3D refractive index values, which directly correspond to physical properties of the flow. We derive a new solution for this reconstruction problem that lends itself to efficient algorithms to robustly work with relatively small numbers of cameras. Our physical system is easy to set up, and consists of an array of relatively low cost rolling-shutter camcorders that are synchronized with a new approach. We demonstrate our method with real measurements, and analyze precision with synthetic data for which ground truth information is available.


Measuring BRDFs of Immersed Materials

Kai Berger, Ilya Reshetouski, Marcus Magnor, Ivo Ihrke
In: Proceedings of VMV 2011.


We investigate the effect of immersing real-world materials into media of different refractive indices. We show, that only some materials follow the Fresnel-governed behaviour. In reality, many materials exhibit unexpected effects such as stronger localized highlights or a significant increase in the glossy reflection due to microgeometry. In this paper, we propose a new measurement technique that allows for measuring the BRDFs of materials that are immersed into different media.


author = {Kai Berger and Ilya Reshetouski and Marcus A. Magnor and Ivo Ihrke},
title = "{Measuring BRDFs of Immersed Materials}",
booktitle = {Proceedings of VMV},
pages = "325--330",
year = {2011},
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