Generalized Image Acquisition and Analysis

From Capture to Simulation - Connecting Forward and Inverse Problems in Fluids

We explore the connection between fluid capture, simulation and proximal methods, a class of algorithms commonly used for inverse problems in image processing and computer vision. Our key finding is that the proximal operator constraining fluid velocities to be divergence-free is directly equivalent to the pressure-projection methods commonly used in incompressible flow solvers. This observation lets us treat the inverse problem of fluid tracking as a constrained flow problem all while working in an efficient, modular framework. In addition it lets us tightly couple fluid simulation into flow tracking, providing a global prior that significantly increases tracking accuracy and temporal coherence as compared to previous techniques. We demonstrate how we can use these improved results for a variety of applications, such as re-simulation, detail enhancement, and domain modification. We furthermore give an outlook of the applications beyond fluid tracking that our proximal operator framework could enable by exploring the connection of deblurring and fluid guiding.


Fluorescent Immersion Range Scanning

Matthias Hullin, Martin Fuchs, Ivo Ihrke, Hans-Peter Seidel, Hendrik P. A. Lensch
In: Proceedings of SIGGRAPH 2008.


The quality of a 3D range scan should not depend on the surface properties of the object. Most active range scanning techniques, however, assume a diffuse reflector to allow for a robust detection of incident light patterns. In our approach we embed the object into a fluorescent liquid. By analyzing the light rays that become visible due to fluorescence rather than analyzing their reflections off the surface, we can detect the intersection points between the projected laser sheet and the object surface for a wide range of different materials. For transparent objects we can even directly depict a slice through the object in just one image by matching its refractive index to the one of the embedding liquid. This enables a direct sampling of the object geometry without the need for computational reconstruction. This way, a high-resolution 3D volume can be assembled simply by sweeping a laser plane through the object. We demonstrate the effectiveness of our light sheet range scanning approach on a set of objects manufactured from a variety of materials and material mixes, including dark, translucent and transparent objects.
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title = "Fluorescent Immersion Range Scanning",
author = "Matthias B. Hullin and Martin Fuchs and Ivo Ihrke and Hans-Peter Seidel and
Hendrik P. A. Lensch",
journal = "ACM Transactions on Graphics",
volume = 27,
number = 3,
month = aug,
year = 2008,
pages = "87:1--87:10",
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