Time-resolved 3d capture of non-stationary gas flows

Abstract

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 that 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.

Synchronization and rolling shutter compensation for consumer video camera arrays

“…We have used the two methods presented in this paper in several capture projects, including time-resolved reconstruction of non-stationary gas flows [2], multi-view stereo reconstruction [3] of video sequences, and time-varying deformable object capture similar to Bradley et al [4]. Together, the two approaches for rolling shutter compensation and synchronization enable the use of rolling shutter cameras in a large range of computer vision applications.…”

Data acquisition and simulation of natural phenomena

“…Atcheson et al [16] gave the fire simulation results by using the real measured data of the hot air flow on the gas flame, as shown in Figure 5-7.…”

“…[16,54,65] introduced some methods to acquire and simulate the values of time-varying fluids. Their methods are also valid for the acquisition of smog data.…”

“…The physics-based astronomical phenomena [8][9][10][11] and atmospheric phenomena [12,13] are simulated in Germany Braunschweig University. Canadian British Columbia University conducted research on light field rendering, capture [14,15] and the 3D capture of non-stationary gas flows [16]. Recently Beihang University started research on smoke data acquisition and reconstruction [17].…”

“…(a) Background distortion caused by floating hot air, observed by camera; (b) 2D distorted vector image abstracted by light-fluid method; (c) visualization of 3D gradient field reconstructed with 16 camcorders; (d) rendering effect of final diffraction field after Poisson integration[16].…”