Take the center of the goal as (0,0).
y (vertical axis)
^

0 
ball 

<x> (horizontal)
 In intellibrain@yahoogroups.com, "Peter Chatterton" <peter@...> wrote:
>
> How can you 'capture the x and y' positions when you just have
> an endon view?
>
> Are you sure that the height of the ball isn't variable as well?
>
> Peter
>
>  Original Message 
> From: blescohier
> To: intellibrain@yahoogroups.com
> Sent: Tuesday, October 06, 2009 11:17 AM
> Subject: [intellibrain] Re: Soccer Robot ...
>
>
> What are you considering as the x and y axes? I assume that x is 'right and left' as the goalie looks at the playing field, and that y is up and down.
>
> In that case, 2 points define a line and the time it takes the ball to get from one point to the other is your ball.x and ball.y velocities. Capture the x and y position of the ball every t milliseconds, use the distance formula (http://www.purplemath.com/modules/distform.htm) to determine the distance traveled, and then use the velocity of the ball (v = d/t) to predict the position where the ball will cross the goal line. If that position is inside the goal, move the robot to that position... if that position is outside your goal, let it go... it will miss the goal and be a goalie kick.
>
> Bill
>
>  In intellibrain@yahoogroups.com, COE SECTIONB <coesectionb@> wrote:
> >
> > To Peter and Paul:
> > Thank you guys for your effort and idea.....i appreciate it so much...But if you have any idea about soccer robot (goal keeper) using cmucam, please post it here..especially it discuss about getting the trajectory line of the ball and getting the global coordinates of it....
> >
>