Pixel position of circle on image

1 次查看（过去 30 天）
sangeeta
sangeeta 2013-3-21
How to find and store in list(x1y1, x2y2, x3y3, ...... xnyn)all the pixel positions that a circle would cross, on an image, given only the center point (x,y) and radius of circle. There is no actual circle.

请先登录，再回答此问题。

回答（2 个）

Sven
Sven 2013-3-21
编辑：Sven 2013-3-21
Sangeeta, does this answer your question:
center = [25 30]; %XY location of circle center
radius = 15;
matSize = 50;
[X,Y] = meshgrid(1:matSize,1:matSize);
distFromCenter = sqrt((X-center(1)).^2 + (Y-center(2)).^2);
onPixels = abs(distFromCenter-radius) < 0.5;
[yPx,xPx] = find(onPixels); % THIS is your answer!
figure, plot(xPx,yPx,'g.', center(1),center(2),'ro')
rectangle('Position',[center-radius [2 2]*radius], 'Curvature',[1 1])
axis image
  1 个评论
sangeeta
sangeeta 2013-4-16
Thanks Sven for the code, but seems little difficult to grasp for me. I managed to find out pixels using
if true
r = 60;
theta = 0 : (2 * pi / 10000) : (2 * pi);
pline_x = r * cos(theta) + centx;
pline_y = r * sin(theta) + centy;
end

请先登录，再进行评论。

Image Analyst
Image Analyst 2013-5-19
The answer to this is given in the FAQ: http://matlab.wikia.com/wiki/FAQ#How_do_I_create_a_circle.3F
xCenter = 12;
yCenter = 10;
theta = 0 : 0.01 : 2*pi;
radius = 5;
x = radius * cos(theta) + xCenter;
y = radius * sin(theta) + yCenter;
plot(x, y);
axis square;
xlim([0 20]);
ylim([0 20]);
grid on;

类别

在 Help Center 和 File Exchange 中查找有关 Geometric Transformation and Image Registration 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by