How to get the intersection points ??
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Hi all, I have the following code to get the intersection points between these multiple lines and these multiple circles.
%%center of circles
X = [0.02 0.44; 0.08 0.58 ;...
0.22 0.57; 0.3 0.9; ...
0.44 0.79; 0.35 0.318;...
0.54 0.29; 0.95 0.11;...
0.93 0.7; 0.82 0.93];
C_M=[X(:,1) X(:,2)];
hold on
%%Assign labels to the points.
Assign_labels_to_all_points ( X ,X(:,1),X(:,2))
hold on
%%Draw circles
theta = linspace(0,2*pi) ;
x = 0.15*cos(theta) ; y =0.15*sin(theta) ;
C_M=[X(:,1),X(:,2)];
deg = 0 : 2.5 : 90;
for i=1:length(deg)
r =2;
x_ax = r*[zeros(size(deg(i))) cosd(deg(i))];
y_ax = r*[zeros(size(deg(i))) sind(deg(i))];
%%plot lines with different angles
plot(x_ax, y_ax, 'LineWidth',1.3)
for index = 1:length(C_M)
if ~isinf(C_M(index))
xx = x+C_M(index,1);
yy = y+C_M(index,2);
%%plot circles
plot(xx,yy,'-b','linewidth',1.5)
for j=1:length(deg)
P = InterX([x+C_M(index,1);y+C_M(index,2)],[r*[zeros(size(deg(j))) cosd(deg(j))];r*
[zeros(size(deg(j))) sind(deg(j))]]);
%%plot intersection points between lines and circles
plot(P(1,:),P(2,:),'or');
end
end
end
end
%%x and y axis limits
xlim([-0.2,1.2])
ylim([-0.2,1.2])
grid on
grid minor
I used the file exchange function InterX. It only draws the intersection points as the following image. But, I can't get these intersection points to store them in matrix or array.
So, my question is: How to get the intersection points between each line and the circles that intersected with that line and store them in array or matrix?? Any suggestions to modify this code??
1 Comment
Image Analyst
on 1 Feb 2020
Original question (in case he delete this one also):
How to get the intersection points between (each line and the circles that intersected with that line)??
Hi all, I have the following code to get the intersection points between these multiple lines and these multiple circles.
%%center of circles
X = [0.02 0.44; 0.08 0.58 ;...
0.22 0.57; 0.3 0.9; ...
0.44 0.79; 0.35 0.318;...
0.54 0.29; 0.95 0.11;...
0.93 0.7; 0.82 0.93];
C_M=[X(:,1) X(:,2)];
hold on
%%Assign labels to the points.
Assign_labels_to_all_points ( X ,X(:,1),X(:,2))
hold on
%%Draw circles
theta = linspace(0,2*pi) ;
x = 0.15*cos(theta) ; y =0.15*sin(theta) ;
C_M=[X(:,1),X(:,2)];
deg = 0 : 2.5 : 90;
for i=1:length(deg)
r =2;
x_ax = r*[zeros(size(deg(i))) cosd(deg(i))];
y_ax = r*[zeros(size(deg(i))) sind(deg(i))];
%%plot lines with different angles
plot(x_ax, y_ax, 'LineWidth',1.3)
for index = 1:length(C_M)
if ~isinf(C_M(index))
xx = x+C_M(index,1);
yy = y+C_M(index,2);
%%plot circles
plot(xx,yy,'-b','linewidth',1.5)
for j=1:length(deg)
P = InterX([x+C_M(index,1);y+C_M(index,2)],[r*[zeros(size(deg(j))) cosd(deg(j))];r*
[zeros(size(deg(j))) sind(deg(j))]]);
%%plot intersection points between lines and circles
plot(P(1,:),P(2,:),'or');
end
end
end
end
%%x and y axis limits
xlim([-0.2,1.2])
ylim([-0.2,1.2])
grid on
grid minor
I used the file exchange function InterX. It only draws the intersection points as the following image. But, I can't get these intersection points to store them in matrix or array.
So, my question is: How to get the intersection points between each line and the circles that intersected with that line and store them in array or matrix?? Any suggestions to modify this code??
Accepted Answer
Can't you just modify as follows,
P{i,j} = InterX([x+C_M(index,1);y+C_M(index,2)],[r*[zeros(size(deg(j))) cosd(deg(j))];r*
[zeros(size(deg(j))) sind(deg(j))]]);
%%plot intersection points between lines and circles
plot(P{i,j}(1,:),P{i,j}(2,:),'or');
6 Comments
Matt J
on 18 Aug 2018
The 2x0 contents are the values. I assume this means that no intersection was detected.
Matt J
on 18 Aug 2018
P(cellfun('isempty',P))=[];
But if you get rid of them, how will you know which circle/line pair a 2x2 value corresponds to?
Matt J
on 18 Aug 2018
This will give you a map of where the non-empty P{i,j} lie
map=~cellfun('isempty',P)
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