Single-Camera Spin Measurement for Spherical Bodies
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Solution Overview
Problem
Existing methods for measuring the spin of spherical bodies, such as those used in ball sports, are less effective for morphologically diverse spherical bodies and often require multiple devices, making it inconvenient to obtain spin information from a single video captured with a single camera.
Innovation Solution
A measuring device and method that acquires a template image from a video, extracts clipped images with a centered spherical body, calculates similarities/dissimilarities between frames, and estimates spin based on the distribution of these similarities, allowing for automatic spin measurement from a single video captured with a single camera.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor is added to the ball or multiple devices are used to measure spin, then measurement precision can be improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The invention uses a single video camera to capture images of the ball, creating a visual copy of the ball's appearance and motion. By analyzing the sequence of images (video frames) showing the ball's surface features, the system can determine spin without adding physical sensors to the ball. This copying approach allows spin measurement while keeping the measurement device simple and easy to operate.
2Measurement precision
If multiple devices are used to capture ball information, then measurement precision improves, but ease of operation and device complexity worsen
Solution Approach 1:
The video camera performs multiple functions: it captures the ball's position, velocity, and spin information all in one device. The image processing system extracts various ball parameters from the video frames, making the single camera a universal measurement tool that replaces multiple specialized devices while maintaining measurement precision and improving ease of operation.
3Adaptability or versatility
If the spherical body morphology is made diverse for better sport analysis, then adaptability improves, but measurement precision deteriorates
Solution Approach 1:
The invention changes the approach from relying on specific ball morphology to analyzing morphological parameters directly from images. By extracting features such as surface patterns, color distributions, and shape characteristics from video frames, the system can accurately measure spin for various ball types (baseball, golf ball, tennis ball, etc.) without requiring standardized morphology, thus improving both adaptability and maintaining precision.
Data Source
AI summary
A measuring device 101 measures the spin of a spherical body. A templater 102 acquires a template image in which the spherical body is captured from a video in which the spherical body is captured or a photographic image in which the spherical body is captured under photographing conditions comparable to the vireo. A clipper 103 extracts a region similar to the template image from the video and acquires multiple clipped images having the center position and size matched. A calculator 104 calculates and arranges in the chronological order similarities/dissimilarities between the clipped images to acquire a matrix. An estimator 105 estimates the spin of the spherical body from the distribution of elements in the matrix of similarities/dissimilarities.