Prof. Pål Halvorsen Profile

Prof. Pål Halvorsen

at Univ of Oslo

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Author

Publications (2)

Proceedings Article | 28 February 2014 Paper

Automatic exposure for panoramic systems in uncontrolled lighting conditions: a football stadium case study

Vamsidhar Reddy Gaddam, Carsten Griwodz, Pål Halvorsen

Proceedings Volume 9012, 90120C (2014) https://doi.org/10.1117/12.2040145

KEYWORDS: Cameras, Panoramic photography, Video, Imaging systems, Automatic exposure, Light sources and illumination, Visualization, Camera shutters, Calibration, Antennas

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One of the most common ways of capturing wide eld-of-view scenes is by recording panoramic videos. Using an array of cameras with limited overlapping in the corresponding images, one can generate good panorama images. Using the panorama, several immersive display options can be explored. There is a two fold synchronization problem associated to such a system. One is the temporal synchronization, but this challenge can easily be handled by using a common triggering solution to control the shutters of the cameras. The other synchronization challenge is the automatic exposure synchronization which does not have a straight forward solution, especially in a wide area scenario where the light conditions are uncontrolled like in the case of an open, outdoor football stadium. In this paper, we present the challenges and approaches for creating a completely automatic real-time panoramic capture system with a particular focus on the camera settings. One of the main challenges in building such a system is that there is not one common area of the pitch that is visible to all the cameras that can be used for metering the light in order to nd appropriate camera parameters. One approach we tested is to use the green color of the eld grass. Such an approach provided us with acceptable results only in limited light conditions.A second approach was devised where the overlapping areas between adjacent cameras are exploited, thus creating pairs of perfectly matched video streams. However, there still existed some disparity between di erent pairs. We nally developed an approach where the time between two temporal frames is exploited to communicate the exposures among the cameras where we achieve a perfectly synchronized array. An analysis of the system and some experimental results are presented in this paper. In summary, a pilot-camera approach running in auto-exposure mode and then distributing the used exposure values to the other cameras seems to give best visual results.

Proceedings Article | 19 January 2009 Paper

On the influence of latency estimation on dynamic group communication using overlays

Knut-Helge Vik, Carsten Griwodz, Pål Halvorsen

Proceedings Volume 7253, 725307 (2009) https://doi.org/10.1117/12.815561

KEYWORDS: Error analysis, Visualization, Telecommunications, Internet, Control systems, Optimization (mathematics), Detection and tracking algorithms, Network architectures, Analytical research, Information science

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Conference Committee Involvement (4)

Multimedia Computing and Networking 2009

19 January 2009 | San Jose, California, United States

Multimedia Computing and Networking 2008

30 January 2008 | San Jose, California, United States

Multimedia Computing and Networking 2007

31 January 2007 | San Jose, CA, United States

Multimedia Computing and Networking 2006

18 January 2006 | San Jose, California, United States

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