Edge Filtering

So, you want to track a round moving object from a moving viewpoint? How about tracking a balloon from a LEO satellite? If size isn't an issue, golf balls or paintballs would be useful to locate... maybe locating a tire or other round object within a factory/industrual setting.

Hey guys!!!

Why not cricket?

It's the world cup season now!!! Have you seen the replays of LBW appeals that cameras track, for ball trajectory reconstruction? These could be used to assist umpires?

This DSP processing is real cute!

Herbieboy,

This is not in any way a trivial exercise, and just trying to locate circular objects (in practice, arcs since portions of the whole circle will typically be occluded) is by itself almost certainly doomed to failure in any situation where multiple circles and arcs are present in any number, against varying backgrounds as in a football (soccer) game. Trying to do it over the whole field, from one camera in real time would require more imaging processing capability than I'm sure would be available, and even with other algorithms assisting to narrow the likely visual field to be processed is still a major challenge, and prone to error.

You have provided only the sketchiest of overall details, but if I understand you correctly, the edge filtering/detection of circular objects is set in stone, and what is needed is a way to test/refine and demonstrate it.

Perhaps a tennis match, with (only) an aerial view of the moving ball superimposed on a background diagram of a court and net. In other words, detect the ball, remove all other visual details and superimpose it over a fixed but appropriately scaled diagram of the court, so that what you would end up with would look something like "Pong" when viewed, except it would reflect an actual tennis match in progress.

Regards, Greg

My apologies over the sketchy details, your comments ,however, are much appreciated.

Both the cricket and tennis ideas may work but I will have to look into the size issue/constraints. I would definitely have to determine applications for 'round object in an industrial setting'. All ideas are welcome

Many thanks

Does the software and/or detection system have any color recognition capabilities?

If so, you might filter for the color of the subject or filter out all but that color. For a start look into candy/food manufacturing systems, spectrum analyzers, print and video processing for color and shape recognition systems/software

I think the answer depends on the exact reason she's trying to do it and what the frame rate has to be. If it's purely an academic exercise she'd probably be better off doing a more controlled experiment. If it's a real world commercial product than it has to handle a lot more...

I don't know if football is cliche or not, but it would definitely be tough since often the ball is hidden by the players body, the ball is an anisotropic shape, the lighting is inconsistent, etc. Plus the ball is so small compared to the field of view. Tennis seems good, but she may have real issues with motion blur if the frame rate isn't high enough since the ball is moving so fast.

Not sure if she has to use any special software or not, but may want to check out National Instruments vision products. You can get demos at www.ni.com. They have algorithms for circle detection even if they are partially occluded. Also they have a product called Vision Builder for Automated Inspection that's very user friendly and good to prototype with even if you are going to program it in a different language.

You mention edge filtering, but that is only one of many techniques. IMHO, it doesn't sound like the best one for this application, but it depends on the purpose of the application.

This is the best book I've found on the subject:

The Image Processing Handbook by Dr. John Russ
http://www.amazon.com/Image-Processing-Handbook-Fifth/dp/other-editions/0849372542/ref=dp_ed_all/103-0514669-8539803

It has many examples of techniques that would be applicable to the project.

Hope this helps. If you could post more details, may be able to provide more info.

Mike

Post #5 mentioned color recognition. This could be a great venue since colors can be filtered in "ranges" of wavelengths (hue) depth (saturation), and gamma (illumination relative to contrast), and so the object can be isolated even as some minute changes in hue appear, following angle of shot, exposure to different light conditions, etc.

It has a real meaning in living of tv field gethering. yet Im very interesting in the tech, although its quit out of my depth. and I hvnt got chance to do the task. Thats why we dare not to return a reply until this day. I dont know if useful. many years ago, I read a paper which is dedcate on acquire rotation speed and direction of a pingpng ball. its depond on mark brand print on the ball. its good idea to recognization. As to football, the edge filtering and template fit is often used to captuer object. Canny and Laplace sharpness is very ordinary method. and there are lots of programme for reference. I think your friend can find them easily in their college. besides, matlab is also best bet for graphic processing. mjv aslo give a good clue that indeed NI has a suit of plan for the project, not only for software but for hard grahpic card. its also easily to use. now its 8 version as I know. color splite is very often used in tv pic processing. it uses color defference saperate different background. the tech is called "color key" or "x" circuit.its one of the main tool in tv station. in virtual studion, it takes a important role. you can also refer to "photoshop" software, they have its application very well.