# How to convert arc circle plot into binary circle?

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afiq rauf on 17 Jun 2021
Answered: Walter Roberson on 19 Jun 2021
how to change the circumference into binary circle ?

KSSV on 17 Jun 2021
R = 1;
th = linspace(0,2*pi,1000) ;
x = R*cos(th) ; y = R*sin(th) ;
xi = linspace(-2,2,100) ;
yi = linspace(-2,2,100) ;
[X,Y] = meshgrid(xi,yi) ;
Z = zeros(100) ;
idx = knnsearch([X(:) Y(:)],[x' y']) ;
Z(idx) = 1 ;
imagesc(Z)
Walter Roberson on 19 Jun 2021
Change
th = linspace(0,2*pi,1000) ;
to only have the range of angles that you want the arc to cover.

Walter Roberson on 19 Jun 2021
But for your purpose, instead of using plot(), multiply the coordinates by the resolution you want, and round() them, and then subtract off the minimum x and y . Now you have matrix coordinates.
resolution = 25;
th = linspace(0, 7*pi/9, 500);
r = 5;
xc = 3;
yc = 7;
[x,y] = pol2cart(th, r);
x = x + xc;
y = y + yc;
%the above are data coordinates. Make them into array coordinates.
buffer = 5;
xm = round(x * resolution);
ym = round(y * resolution);
xmin = min(xm);
ymin = min(ym);
xmax = max(xm);
ymax = max(ym);
xmc = xm - xmin + 1 + buffer;
ymc = ym - ymin + 1 + buffer;
arc_image = accumarray([ymc(:), xmc(:)], 1);
imshow(arc_image)