plot ellipses by clicking points?

2018 9 17
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更新时间：2018 10 17
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How to plot ellipses by clicking on the points. I have a 100*100 cm grid and I would like to generate ellipses in it by clicking different positions. Is there a way to do it? The ellipses can intersect and thereby I need to detect the high region of intersection.

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KSSV
KSSV 2018-9-17
You want to click and make the center? Do you have minor, major axis data? Or you want to click the entire ellipse?
Ramesh Bala
Ramesh Bala 2018-9-17
function gridplot
axis([0 100 0 100])
rectangle('Position',[0 0 100 100]) grid on
hold on
X = [10 90 90 20 50 90 40 20 90 ];
Y = [10 10 20 30 50 60 70 80 90 ];
% Create plot plot(X,Y,'MarkerFaceColor',[0.847058832645416 0.160784319043159 0],...
'Marker','o',...
'LineStyle','none',... 'Color',[1 0 0]);
txt1 = ' 7';
text(X(1),Y(1),txt1)
txt2 = ' 2'; text(X(2),Y(2),txt2) txt3 = ' 3';
text(X(3),Y(3),txt3)
txt4 = ' 4'; text(X(4),Y(4),txt4) txt5 = ' 5';
text(X(5),Y(5),txt5)
txt6 = ' 6'; text(X(6),Y(6),txt6) txt7 = ' 1';
text(X(7),Y(7),txt7)
txt8 = ' 8'; text(X(8),Y(8),txt8) txt9 = ' 9';
text(X(9),Y(9),txt9)
xlabel({'Length','(cm)'})
ylabel({'Width', '(cm)'})
ax = gca; ax.XRuler.Axle.LineWidth = 2; ax.YRuler.Axle.LineWidth = 2;
GridLineWidth = 2;
end
This is my code, I would like to select marker points and create ellipses from it.
Ramesh Bala
Ramesh Bala 2018-9-17
whether imellipse or drawellipse works in this case?
Ramesh Bala
Ramesh Bala 2018-9-18
I believe imellipse is already a preloaded one where one just clicks and drag the ellipse, can it be modified based on the above case?

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KSSV
KSSV 2018-9-18
编辑：KSSV 2018-9-18

1 个投票

figure
hold on
axis equal
t=-pi:0.01:pi;
for i = 1:10
a=10; % horizontal radius
b=5; % vertical radius
[x0,y0] = getpts() ;
x=x0(1)+a*cos(t);
y=y0(1)+b*sin(t);
plot(x,y)
drawnow
end

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Ramesh Bala
Ramesh Bala 2018-9-18
Thanks KSSV,I'm expecting to do it in another way with user interface by direct clicks
KSSV
KSSV 2018-9-18
Edited answer....double click at a point, when figure is prompted
Ramesh Bala
Ramesh Bala 2018-9-18
That's interesting good option drawnow ,never knew that.Thanks.But the picture obtained looked like this with varying thickness?
KSSV
KSSV 2018-9-18
There is a problem with clicking....you should double click ..fast...edited the code...
Ramesh Bala
Ramesh Bala 2018-9-18
thanks, lemme have a check.Is there any reason for keeping a,b constant. Can't it be like
a = (x0(1)+x0(2))./2;
b = (y0(1)+y0(2))./2;
or do you have other choices?
KSSV
KSSV 2018-9-18
That is your choice..you should be knowing....they determine the size/ radii of ellispes.
Ramesh Bala
Ramesh Bala 2018-10-17
Thanks for the comments; this is the overall script created. But the problem is that it's moving away from the boundary. Of course, I know it's based on the radii size as we mention, but is there any way to constrain that within boundary ??
function ellipsedrawon
clear
close uiopen
t=-pi:0.01:pi;
for i = 1:20
%getting the points
[x0,y0] = ginput(2) ;
% a =10;
% b =5;
% a = (x0(1)+x0(2))./2; % horizontal radii
b = (y0(1)+y0(2))./2; % vertical radii
% x,y ellipse plot
x=x0(1)+a*cos(t);
y=y0(1)+b*sin(t);
plot(x,y)
drawnow
end

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