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.
Projects
Property and Lighting Manipulations for Static Volume Stylization Using a Painting Metaphor
TVCG 2014
Abstract
Although volumetric phenomena are important for realistic
rendering and can even be a crucial component in the image,
the artistic control of the volume’s appearance is
challenging. Appropriate tools to edit volume properties are
missing, which can make it necessary to use simulation
results directly. Alternatively, high-level modifications
that are rarely intuitive, e.g., the tweaking of noise
function parameters, can be utilized.
Our work introduces a solution to stylize single-scattering
volumetric effects in static volumes. Hereby, an artistic
and intuitive control of emission, scattering and extinction
becomes possible, while ensuring a smooth and coherent
appearance when changing the viewpoint. Our method is based
on tomographic reconstruction, which we link to the
volumetric rendering equation. It analyzes a number of
target views provided by the artist and adapts the volume
properties to match the appearance for the given
perspectives. Additionally, we describe how we can optimize
for the environmental lighting to match a desired scene
appearance, while keeping volume properties
constant. Finally, both techniques can be combined. We
demonstrate several use cases of our approach and illustrate
its effectiveness.
Video Bibtex
@article{Klehm:14,
author = {Oliver Klehm and Ivo Ihrke and Hans-Peter Seidel and Elmar Eisemann},
title = {Property and Lighting Manipulations for Static Volume Stylization Using a Painting Metaphor},
journal = {Transactions of Visualization and Computer Graphics},
year = 2014,
pages = {xx--yy},
}
author = {Oliver Klehm and Ivo Ihrke and Hans-Peter Seidel and Elmar Eisemann},
title = {Property and Lighting Manipulations for Static Volume Stylization Using a Painting Metaphor},
journal = {Transactions of Visualization and Computer Graphics},
year = 2014,
pages = {xx--yy},
}