| Conference |
| Type of Publication |
| Robust Camera Calibration for Sport Videos using Court
Models |
| Title |
|
Susanne Krabbe
Peter H. N. de With
|
| Authors |
| SPIE Storage and Retrieval Methods and Applications
for Multimedia, San José, CA, January 2004 |
| Published in |
| We propose an automatic camera calibration
algorithm for court sports. The obtained camera calibration
parameters are required for applications that need to convert
positions in the video frame to real-world coordinates or vice
versa. Our algorithm uses a model of the arrangement of court
lines for calibration. Since the court model can be specified by
the user, the algorithm can be applied to a variety of different
sports.The algorithm starts with a model initialization step
which locates the court in the image without any user assistance
or a-priori knowledge about the most probable position. Image
pixels are classified as court line pixels if they pass several
tests including color and local texture constraints. A Hough
transform is applied to extract line elements, forming a set of
court line candidates. The subsequent combinatorial search
establishes correspondences between lines in the input image and
lines from the court model. For the succeeding input frames, an
abbreviated calibration algorithm is used, which predicts the
camera parameters for the new image and optimizes the parameters
using a gradient-descent algorithm.We have conducted experiments
on a variety of sport videos (tennis, volleyball, and goal area
sequences of soccer games). Video scenes with considerable
difficulties were selected to test the robustness of the
algorithm. Results show that the algorithm is very robust to
occlusions, partial court views, bad lighting conditions, or
shadows. |
| Abstract |
|
sport video processing
camera calibration
pose estimation
model-based video analysis
|
| Keywords |
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