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Calibration of extrinsic camera parameters by identifying lines in a monocular view of a soccer field

Broddegård, Oscar LU and Ringström, Caesar (2024) In LUTFMA-3541-2024 FMAM05 20241
Mathematics (Faculty of Engineering)
Abstract
Soccer is witnessing technological advancements in a variety of areas, of which
many are dependent on camera calibration. This thesis addresses the challenge of
calibrating the extrinsic parameters of cameras used in soccer broadcasts using a
monocular view of the field. Accurate camera calibration is essential for various
applications such as player positioning, field modelling, and improving the overall broadcast quality. This research focuses on evaluating techniques for detecting
lines on the soccer field and using these lines to estimate the camera’s position and orientation, and the field’s aspect ratio. The study explores multiple line detection methods, including traditional line detection techniques like Hough Transformation... (More)
Soccer is witnessing technological advancements in a variety of areas, of which
many are dependent on camera calibration. This thesis addresses the challenge of
calibrating the extrinsic parameters of cameras used in soccer broadcasts using a
monocular view of the field. Accurate camera calibration is essential for various
applications such as player positioning, field modelling, and improving the overall broadcast quality. This research focuses on evaluating techniques for detecting
lines on the soccer field and using these lines to estimate the camera’s position and orientation, and the field’s aspect ratio. The study explores multiple line detection methods, including traditional line detection techniques like Hough Transformation (HT) and Line Segment Detector (LSD), as well as advanced approaches like Holistically Attracted Wireframe Parsing (HAWP) and Semantic Line Detection (SLNet). Each method’s performance is evaluated based on accuracy, robustness, and computational efficiency. The proposed pipeline leverages detected field lines to calibrate the camera by estimating a plane-induced homography, mapping image points to world coordinates. The calibration process is validated through reprojection error analysis, ensuring the detected lines and their intersections provide reliable input for camera pose estimation, and that the assumptions of a planar rectangular field are valid. Results indicate that HAWP outperforms the other tested methods in detecting soccer field lines, but since it leverages detected junctions to find lines it becomes very sensitive to occlusions. While other tested methods show some potential, they require further refinement for consistent performance. Furthermore, the camera calibration algorithm based on the homography shows promising results, suggesting that the field geometry assumptions are valid. Finally, a proposition of further development is presented, providing a foundation for future research within the field. (Less)
Please use this url to cite or link to this publication:
author
Broddegård, Oscar LU and Ringström, Caesar
supervisor
organization
course
FMAM05 20241
year
type
H2 - Master's Degree (Two Years)
subject
keywords
camera calibration, line detection, homography, monocular view
publication/series
LUTFMA-3541-2024
report number
LUTFMA-3541-2024
ISSN
1404-6342
other publication id
2024:E33
language
English
additional info
Supervisor (outside LU): Haochen Liu (Spiideo AB)
id
9169307
date added to LUP
2025-09-15 11:16:20
date last changed
2025-09-15 11:16:20
@misc{9169307,
  abstract     = {{Soccer is witnessing technological advancements in a variety of areas, of which
many are dependent on camera calibration. This thesis addresses the challenge of
calibrating the extrinsic parameters of cameras used in soccer broadcasts using a
monocular view of the field. Accurate camera calibration is essential for various
applications such as player positioning, field modelling, and improving the overall broadcast quality. This research focuses on evaluating techniques for detecting
lines on the soccer field and using these lines to estimate the camera’s position and orientation, and the field’s aspect ratio. The study explores multiple line detection methods, including traditional line detection techniques like Hough Transformation (HT) and Line Segment Detector (LSD), as well as advanced approaches like Holistically Attracted Wireframe Parsing (HAWP) and Semantic Line Detection (SLNet). Each method’s performance is evaluated based on accuracy, robustness, and computational efficiency. The proposed pipeline leverages detected field lines to calibrate the camera by estimating a plane-induced homography, mapping image points to world coordinates. The calibration process is validated through reprojection error analysis, ensuring the detected lines and their intersections provide reliable input for camera pose estimation, and that the assumptions of a planar rectangular field are valid. Results indicate that HAWP outperforms the other tested methods in detecting soccer field lines, but since it leverages detected junctions to find lines it becomes very sensitive to occlusions. While other tested methods show some potential, they require further refinement for consistent performance. Furthermore, the camera calibration algorithm based on the homography shows promising results, suggesting that the field geometry assumptions are valid. Finally, a proposition of further development is presented, providing a foundation for future research within the field.}},
  author       = {{Broddegård, Oscar and Ringström, Caesar}},
  issn         = {{1404-6342}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{LUTFMA-3541-2024}},
  title        = {{Calibration of extrinsic camera parameters by identifying lines in a monocular view of a soccer field}},
  year         = {{2024}},
}