scholarly journals A Tool for Annotating Homographies from Hockey Broadcast Video

2021 ◽  
Vol 6 (1) ◽  
pp. 1-3
Author(s):  
Pascale Walters ◽  
Mehrnaz Fani ◽  
David Clausi ◽  
Alexander Wong
Keyword(s):  
Camera Calibration ◽  
Ground Truth ◽  
Improve Accuracy ◽  
Broadcast Video ◽  
Camera Parameters ◽  
Overhead View ◽  
Automatic Camera Calibration ◽  
Calibration Techniques

In order to develop solutions for automatic ice rink localization from broadcast video, a dataset with ground truth homographies is required. Hockey broadcast video does not tend to provide camera parameters for each frame, which means that they must be gathered manually. A novel tool for collecting ground truth transforms through point correspondences between each frame and an overhead view of the ice rink is presented in this paper. Through collaboration with the users of the tool, we have added features to improve accuracy and efficiency, especially in frames with few lines on the playing surface visible. A dataset of 4,262 frames has been collected, which will be used for research into automatic camera calibration techniques.

An Enhanced On-Line Service for 3D Model Construction from Photographs

2012 ◽  
Vol 1 (2) ◽  
pp. 277-294 ◽  
Author(s):  
David Tingdahl ◽  
Gool Van Luc
Keyword(s):  
3D Reconstruction ◽  
Web Service ◽  
Camera Calibration ◽  
3D Model ◽  
Digital Camera ◽  
Calibration Method ◽  
Complete Model ◽  
On Line ◽  
Automatic Camera Calibration ◽  
Calibration Techniques

We present a web service for image based 3D reconstruction. The system allows a cultural heritage professional to easily create a 3D model of a scene or object out of images taken from different viewpoints. The user uploads the images to our server on which all processing takes place, and the final result can be downloaded upon completion. Any consumer-class digital camera can be used, and the system is free to use for non-commercial purposes. The service includes a number of innovations to greatly simplify the process of taking pictures suitable for reconstruction. In particular, we are able to construct models of planar scenes and from photographs shot using a turntable, and at varying zoom levels. Although the first two may seem like particularly simple cases, they cause some mathematical issues with traditional self-calibration techniques. We handle these cases by taking advantage of a new automatic camera calibration method that uses meta-data stored with the images. For fixed-lens camera setups, we can also reuse previously computed calibrations to support otherwise degenerate scenes. Furthermore, we can automatically compute the relative scale and transformation between two reconstructions of the same scene, merging two reconstructions into one. We demonstrate the capabilities of the system by two case studies: turntable reconstruction of various objects and the reconstruction of a cave, with walls and roof integrated into a complete model.

scholarly journals Constrained Multiple Planar Reconstruction for Automatic Camera Calibration of Intelligent Vehicles

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4643
Author(s):  
Sang Jun Lee ◽  
Jeawoo Lee ◽  
Wonju Lee ◽  
Cheolhun Jang
Keyword(s):  
Camera Calibration ◽  
Calibration Method ◽  
Image Features ◽  
Intelligent Vehicles ◽  
Point Problem ◽  
Reconstruction Method ◽  
Calibration Methods ◽  
The World ◽  
Extrinsic Parameters ◽  
Automatic Camera Calibration

In intelligent vehicles, extrinsic camera calibration is preferable to be conducted on a regular basis to deal with unpredictable mechanical changes or variations on weight load distribution. Specifically, high-precision extrinsic parameters between the camera coordinate and the world coordinate are essential to implement high-level functions in intelligent vehicles such as distance estimation and lane departure warning. However, conventional calibration methods, which solve a Perspective-n-Point problem, require laborious work to measure the positions of 3D points in the world coordinate. To reduce this inconvenience, this paper proposes an automatic camera calibration method based on 3D reconstruction. The main contribution of this paper is a novel reconstruction method to recover 3D points on planes perpendicular to the ground. The proposed method jointly optimizes reprojection errors of image features projected from multiple planar surfaces, and finally, it significantly reduces errors in camera extrinsic parameters. Experiments were conducted in synthetic simulation and real calibration environments to demonstrate the effectiveness of the proposed method.

Can Computers Outperform Humans in Detecting User Zone-Outs? Implications for Intelligent Interfaces

2022 ◽  
Vol 29 (2) ◽  
pp. 1-33
Author(s):  
Nigel Bosch ◽  
Sidney K. D'Mello
Keyword(s):  
Operating Characteristic ◽  
State Of The Art ◽  
Characteristic Curve ◽  
Ground Truth ◽  
Mind Wandering ◽  
High Stakes ◽  
Machine Learning Model ◽  
Improve Accuracy ◽  
Comparable Accuracy ◽  
Operating Characteristic Curve

The ability to identify whether a user is “zoning out” (mind wandering) from video has many HCI (e.g., distance learning, high-stakes vigilance tasks). However, it remains unknown how well humans can perform this task, how they compare to automatic computerized approaches, and how a fusion of the two might improve accuracy. We analyzed videos of users’ faces and upper bodies recorded 10s prior to self-reported mind wandering (i.e., ground truth) while they engaged in a computerized reading task. We found that a state-of-the-art machine learning model had comparable accuracy to aggregated judgments of nine untrained human observers (area under receiver operating characteristic curve [AUC] = .598 versus .589). A fusion of the two (AUC = .644) outperformed each, presumably because each focused on complementary cues. Furthermore, adding more humans beyond 3–4 observers yielded diminishing returns. We discuss implications of human–computer fusion as a means to improve accuracy in complex tasks.

FEATURE DETECTION AND CORRESPONDENCE FOR CAMERA CALIBRATION

2008 ◽  
Vol 05 (01) ◽  
pp. 41-50 ◽  
Author(s):  
ZHIGANG ZHENG ◽  
ZHENGJUN ZHA ◽  
LONG HAN ◽  
ZENGFU WANG
Keyword(s):  
Camera Calibration ◽  
Feature Detection ◽  
Checkerboard Pattern ◽  
Geometrical Constraint ◽  
Precise Position ◽  
3D Space ◽  
Corner Points ◽  
Calibration Pattern ◽  
Fully Automatic ◽  
Automatic Camera Calibration

This paper addresses the problem of highly accurate, highly speedy, more reliable and fully automatic camera calibration. Our objective is to construct a reliable and fully automatic system to supply a more robust and highly accurate calibration scheme. A checkerboard pattern is used as calibration pattern. After the corner points on image are detected, an improved Delaunay triangulation based algorithm is used to make correspondences between corner points on image and corner points on checkerboard in 3D space. In order to determine precise position of the actual corner points, a geometrical constraint based global curve fitting algorithm has been developed. The experimental results show that the geometrical constraint based method can improve remarkably the performance of the feature detection and camera calibration.

Camera Calibration Techniques

2018 ◽  
pp. 11-61 ◽  
Author(s):  
Hanqi Zhuang ◽  
Zvi S. Roth
Keyword(s):  
Camera Calibration ◽  
Calibration Techniques
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