Record Details

Efficient Incremental Panorama Reconstruction from Multiple Videos

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Title Efficient Incremental Panorama Reconstruction from Multiple Videos
Names Feng, Zhongyuan (creator)
Todorovic, Sinisa (advisor)
Date Issued 2015-05-22 (iso8601)
Note Graduation data: 2015
Abstract Constructing a panorama from a set of videos is a long-standing problem in computer
vision. A panorama represents an enhanced still-image representation of an entire scene
captured in a set of videos, where each video shows only a part of the scene. Importantly,
a panorama shows only the scene background, whereas any foreground objects appearing
in the videos are not of interest. This report presents a new framework for an efficient
panorama extraction from a large set of 140-150 videos, each showing a play in a given
football game. The resulting panorama is supposed to show the entire football field seen
in the videos, without foreground players. Prior work typically processes all video frames
for panorama extraction. This is computationally expensive. In contrast, we design an
efficient approach which incrementally builds the panorama by intelligently selecting a
sparse set of video frames to process. Our approach consists of the following steps. We
first identify the moment of snap (MOS) in each play, because these video frames are
usually captured without camera motion, and thus provide good-quality snap shots of
the field. All detected MOS frames are then used to build an initial panorama using the
standard Bundle Adjustment algorithm. The initial panorama is used in our subsequent
steps to search for new video frames that will maximally cover yet unreconstructed parts
the football field. For this, we compute a homographic projection of the MOS video
frames onto the current panorama, and estimate an area on the reconstructed football
field with the lowest confidence score. The score of an area is made directly proportional
to the number of video frames covering that area. Then, we identify a new sparse set of
video frames that maximally cover the lowest-confidence area in the current panorama.
Finally, this new set of frames and the current panorama are jointly input to the Bundle
Adjustment algorithm to produce a new panorama estimate. This process is iterated
until the confidence scores associated with different parts of the panorama stop changing,
or when there are no new video frames that would extend the current panorama. In each
iteration, we also adaptively build a background model of the football field, and in this
way remove foreground from the panorama. We test our approach on a large dataset of
videos showing 10 football games. The results demonstrate that our approach is more
efficient than state-of-the-art methods, while yielding competitive results. To the best of
our knowledge, prior work has not considered efficiency, but only accuracy of panorama
extraction. Our approach has an advantage of being flexible to various time budgets set
by real-world applications.
Genre Research Paper
Identifier http://hdl.handle.net/1957/55882

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