Video object tracking: ping-pong balls

[awvvu]

I'm interested in determining the trajectory and spin of a ping-pong ball for a project for class. I plan on getting a decent resolution video camera and record the ball (with the camera stationary). Afterward, I'll analyze the video on my computer.

My question is: what kind of algorithm can I get more (detailed) information about so I can go about implementing it myself? What kind of things should I search for to find more information? I have a lot of experience programming (in script languages though), so I think I can pull it off. I realize it's not an easy task though. (and it's really not a big deal if I can't get it to work).

I think if I color the ball a really distinctive and bright color (and do some sort of striping to be able to analyze its spin), it wouldn't be terribly hard to do. I can probably do it a brute-force and slow way by analyzing frame-by-frame and comparing it with previous ones, but I'd like some suggestions before I start hacking away at it.

I also reckon I'll have to figure out how to implement some basic depth perception, but I think that can be determined from knowing the (x,y) coordinates on frame and the apparent size of the ball. Then with some calibration based on my video camera placement, I can approximate its coordinates in three dimensions.

(I wasn't sure which forum to place this in exactly.)

edit: Hrm, I just found a library for computer vision, opencv, which looks like it'll be useful for this.

 

[binzing]

One, this should be in technology.
Two, you could get a macro (AutoHotKey is great and free) and have it do it the slow way. Logger Pro may have a setup to do it.

 

[quicknote]

I would suggest looking into computer vision algorithms for object detection and tracking. Specifically, you can search for algorithms that use feature detection and matching techniques, such as SIFT or SURF, to track the ping-pong ball in each frame of the video. These algorithms can also provide information about the trajectory and spin of the ball.

Additionally, you can explore techniques for motion estimation and optical flow to track the movement of the ball between frames. This can help with determining the speed and direction of the ball.

In terms of implementing these algorithms, using a library like OpenCV can be very helpful. It provides a range of computer vision functions that can be easily integrated into your project. You can also refer to online tutorials and documentation to understand how to use these functions for your specific task.

As you mentioned, using a distinct and bright color for the ball can make it easier to track. However, you can also explore techniques for object segmentation and tracking, which can handle objects of varying colors and textures.

In terms of depth perception, you can try using a single camera with a known focal length and distance from the ball to estimate the depth. Alternatively, you can use a stereo camera setup to capture depth information directly.

Overall, object tracking using computer vision can be a challenging task, but with some research and experimentation, you can achieve accurate results. Good luck with your project!