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imagematlabgeometrypixel

Drawing circles around image pixels with different radius

I'm implementing the scale invariant feature transform algorithm... The entire point of the algorithm is to pinpoint on an image a set of features that can be used in further post-processing. I've succeeded into finding a vector that contains the key points and their co-ordinates in the form[x1co-ordinate y1co-ordinate circle1radius x2co-ordinate y2co-ordinate circle2radius..... N]

My objective is to draw a circle around those pixels... I tried using rectangle('curvature' circle1radius circle1radius) however I can't draw the ellipse around a certain point... Any suggestions? :)

Solution

  • Here is a function I have used for similar things. Maybe it will work.

    function [circlesx, circlesy]=drawCircle(axes_handle,x,y,radius,npoints,c);
angles=0:(2*pi/(npoints-1)):2*pi;
circlesx=radius*cos(angles)+x;
circlesy=radius*sin(angles)+y;
patch(circlesx,circlesy,c);