|Address||Institut für Informatik|
|Room on||Hermann-Rodewald-Straße 3, Room 309a|
|Office hours||by appointment|
Anne Jordt, Claudius Zelenka, Jens Schneider von Deimling, Reinhard Koch, Kevin Köser (2015):
The Bubble Box: Towards an Automated Visual Sensor for 3D Analysis and Characterization of Marine Gas Release Sites
Sensors 2015, 15, 30716-30735.
original publication at Sensors Journal bibtex
Abstract: Several acoustic and optical techniques have been used for characterizing natural and anthropogenic gas leaks (carbon dioxide, methane) from the ocean floor. Here, single-camera based methods for bubble stream observation have become an important tool, as they help estimating flux and bubble sizes under certain assumptions. However, they record only a projection of a bubble into the camera and therefore cannot capture the full 3D shape, which is particularly important for larger, non-spherical bubbles. The unknown distance of the bubble to the camera (making it appear larger or smaller than expected) as well as refraction at the camera interface introduce extra uncertainties. In this article, we introduce our wide baseline stereo-camera deep-sea sensor bubble box that overcomes these limitations, as it observes bubbles from two orthogonal directions using calibrated cameras. Besides the setup and the hardware of the system, we discuss appropriate calibration and the different automated processing steps deblurring, detection, tracking, and 3D fitting that are crucial to arrive at a 3D ellipsoidal shape and rise speed of each bubble. The obtained values for single bubbles can be aggregated into statistical bubble size distributions or fluxes for extrapolation based on diffusion and dissolution models and large scale acoustic surveys. We demonstrate and evaluate the wide baseline stereo measurement model using a controlled test setup with ground truth information.
Claudius Zelenka, Reinhard Koch (2015):
Blind Deconvolution on Underwater Images for Gas Bubble Measurement
Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., XL-5/W5, 239-244, 2015
original publication at Archives of ISPRS bibtex
Abstract: Marine gas seeps, such as in the Panarea area near Sicily (McGinnis et al., 2011), emit large amounts of methane and carbon-dioxide, greenhouse gases. Better understanding their impact on the climate and the marine environment requires precise measurements of the gas flux. Camera based bubble measurement systems suffer from defocus blur caused by a combination of small depth of field, insufficient lighting and from motion blur due to rapid bubble movement. These adverse conditions are typical for open sea underwater bubble images. As a consequence so called ’bubble boxes’ have been built, which use elaborate setups, specialized cameras and high power illumination. A typical value of light power used is 1000W (Leifer et al., 2003).
In this paper we propose the compensation of defocus and motion blur in underwater images by using blind deconvolution techniques. The quality of the images can be greatly improved, which will relax requirements on bubble boxes, reduce their energy consumption and widen their usability.
Claudius Zelenka (2014):
Gas Bubble Shape Measurement and Analysis
in Pattern Recognition, Volume 8753 of LNCS, pp. 743-749. Springer Berlin / Heidelberg
original publication at www.springerlink.com bibtex
Abstract: This work focuses on the precise quantification of bubble streams from underwater gas seeps. The performance of the snake based method and of ellipse fitting with the CMA-ES non-linear optimization algorithm is evaluated. A novel improved snake based method is presented and the optimal choice of snake parameters is studied. A Kalman filter is used for bubble tracking. The deviation between the measured flux and a calibrated flux meter is 4 % for small and 9 % for larger bubbles. This work will allow a better data gathering on marine gas seeps for future climatology and marine research.
Gas Bubble Measurement
In this research area methods for the evaluation of shape and motion of bubbles from |
underwater gas seeps are explored.
The influence of underwater gas seeps on the global climate and ecosystems is an impor-
tant topic in climatology and marine research. The emitted greenhouse gases, mostly
carbon dioxide and methane, have essential impact on the biosphere. Therefore exact
measurement methods are required.
Multiple Object Tracking
Ongoing research with an industry partner for multiple object tracking in large camera systems combining approaches from object tracking and object recognition.
WS 2015 - Computer Graphics - Teaching Assistant
WS 2015 - Computer Systems - Teaching Assistant
SS 2015 - Computer Science for Engineers - Teaching Assistant
WS 2014/2015 - Introduction to Image Processing - Teaching Assistant
SS 2014 - Computer Graphics - Teaching Assistant