Hi,
I assume radio or circumference as ratio of circumference and take that
as
L / C = k , where k is the ratio of circumferece and C is the
circumference
If so then
C = 2 * PI * r
L = k * C
= k * 2 * PI * r
But I'm not sure that my assumption is right or is this you need. Just a
try.
Thanks and Regards,
K.V.Chandra Kumar
On 04/01/2008, James Fang <[EMAIL PROTECTED]> wrote:
>
> It's possible.
>
>
>
> Scan the digital picture pixel by pixel and line by line until you find
> the first line with two black pixels ( the adjacent pixels is counted as
> only one ),name the two pixels a1(xa1,ya1) and b1(xb1,yb2), continue scaning
> and you will get a2(xa2,ya2) and b2(xb2,yb2), a3(xa3,ya3) and b3(xb3,yb3).
>
>
>
> If (ya2-ya1)/(xa2-xa1) = (ya3-ya2)/(xa3-xa2) , then a1 is the first
> intersection. Store the coordenate of a1.
>
> Otherwise, b1 is the first intersection.
>
>
>
> Continue scanning, you will surely find the second intersection and the
> coordinate of the centre of the circle.
>
>
>
> Since you got the 3 point of the triangle, you can caculate the theta
> angle now.
>
>
>
>
>
> And finally, caculate the arc length by PI*r*r*(theta/360)
>
>
>
>
>
>
>
>
> ------------------------------
>
> *发件人:* algogeeks@googlegroups.com [mailto:[EMAIL PROTECTED] *代表
> *Daniel Bastidas
> *发送时间:* 2008年1月4日 10:19
> *收件人:* algogeeks@googlegroups.com
> *主题:* [algogeeks] arc length
>
>
>
> Hi everybody.
>
> How can I find the arc length (L) in the picture attach if the only thing
> I know is the radio of circumference.
> I don´t know the coordenates of the intersection between line and
> circumference neither the theta angle.
> Any idea, it is possible...?.
> Thanks
>
>
> >
>
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