how can a detect and get co-ordinates for a circle with changing size

[CTFC]

Hi,

 I have some experience with Labview but not with image processing, I have a project to keep track of a football and player on a pitch. My question is after thresholding to get a binary image with just the ball and the player how can i detect which is which. The ball will change size as it moves towards or away from the camera. If the ball is far away and is not a perfect circle can i use a circle detection method to find it?

Thanks very much for your replies

[muks]

MY suggestions and queries

• Get the smallest circle details.i.e the farthest point the ball can travel and u need to detect.
• Get the details of how near the ball can come near the camera.
• Football i suppose will have ball and white patches.How have you decided to threshold the image?
• The background variation is always going to be an problem.You always need to eliminate the background.
• Should you continously track the ball? What happens when the ball is not visible to the camera?
• What camera have you planned to use? 

[CTFC]

Thank you for your reply,

The system is intended for free kicks with a player practicing on his/her own. The camera will detect where in the goals the ball goes in and also where the player is when it does. 

So the ball will be quite small at times depending on how far away the goals are. It could be anywhere from 10 to 25 yards away.

I had thought i could use background subtraction to seperate the ball and player with an image of the emtpy pitch as a background. And also maybe use the colour of the ball and players jersey to threshold the image. The ball only needs to be tracked if it comes near the goals but i will probably need to always track the player. I plan to use a usb camera but have not chosen one yet. My apologies if some of my ideas are a bit off, i am quite new to this.

[muks]

Ok so the next set of suggestions and queries

• ---

  The system is intended for free kicks with a player practicing on his/her own. The camera will detect where in the goals the ball goes in and also where the player is when it does. 

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  This kinda lessens the complication.So now you can place the camera near the corner kick so that the ball size will not change much(Comparitively)
• You can use two cameras for better result.Say one in each corner.

• ---

  The camera will detect where in the goals the ball goes in and also where the player is when it does.
  

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  I am not able to get this line.A better explanation will be helpful
• Are going to need a complex system like the camera should rotate and track the ball or something like that?

By the way Is this a project or just your conseptualisation?

[CTFC]

Sorry, I havnt explained the problem very clearly. The free kicks will be taken from outside the penalty area. They will be shots on goal. The system is intented to be installed in a fenced astro-turf training pitch. The camera would be mounted on the fence a few metres from where the shot will be taken. So i think that the size may differ by half. The results are used to graph where shots are taken from and where they go in the goals.

I was worried that if the ball changes size and my size perameters are wide, the system might start tracking any stray particles left after thresholding. Is searching by shape out of the question?

This project is intended as a college project.

Message Edited by CTFC on 08-19-2008 07:44 AM

[muks]

Ok so here we go again

• ---

  The system is intented to be installed in a fenced astro-turf training pitch.

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  So how are you planning to install the system  with all the wires ?Planning to use a wireless camera?
• How are you going to tackle the vibrations?
• You still have not answered my question of whether u want to track the ball or view the play area

[muks]

How are you planning to bring the ball into focus?

[CTFC]

Its just a prototype so im planning to just use wires. Vibration shouldnt be a problem because it will be a seperate wall to where the ball is hitting so if i secure it well i dont think there will be much vibration. I hadnt thought about bringing the ball into focus. How can this be done? Is it necessary?

[muks]

Are you confident of thresholding the ball properly.How have you planned to do it?

[muks]

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Ok so here we go again

• ---

  The system is intented to be installed in a fenced astro-turf training pitch.

  ---

  So how are you planning to install the system  with all the wires ?Planning to use a wireless camera?
• How are you going to tackle the vibrations?
• You still have not answered my question of whether u want to track the ball or view the play area

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