Why polyxpoly does not work?
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I have the data points for tow polylines as attached. Where A1 is X-data for polyline 1, B1 is Y-data for polyline 1 and,A2 is X-data for polyline 2 and B1 is Y-data for polyline 2. (as plotted)
I tried to get the intersection point between the two polylines using polyxpoly. But the the result for [xi, yi] are empty !!!
Does anyone has an idea what would be the problem ? Thank you so much...
[xi, yi] = polyxpoly(A1, B1,A2, B2);
plot(xi, yi, 'bo')
Matt J on 24 Apr 2018
Edited: Matt J on 24 Apr 2018
I suspect the problem has to do with the fact that you are entering superfluous additional points, which are not actually vertices. A vertex technically should lie only at the end points of the polygon edges.
Regardless, the attached version of polyxpoly by Bruno Luong is working fine for me, but has a different syntax.
>> ab = polyxpoly([A1, B1].',[A2, B2].')
More Answers (1)
Steven Lord on 24 Apr 2018
If you're using release R2017b or later, consider creating polyshape objects and using the intersect function on those objects.
% Load data
D = load('A1', 'A1'); A1 = D.A1;
D = load('A2', 'A2'); A2 = D.A2;
D = load('B2', 'B2'); B2 = D.B2;
D = load('B1', 'B1'); B1 = D.B1;
% Create two polyshape objects
P1 = polyshape(A1, B1, 'Simplify', true);
P2 = polyshape(A2, B2, 'Simplify', true);
% Plot the two polyshape objects so later we can check that the intersection is correct
h1 = plot([P1, P2]);
ax1 = ancestor(h1(1), 'axes');
% Determine the intersection of the two polyshape objects
C = intersect(P1, P2);
% Plot the intersection
h2 = plot(C);
ax2 = ancestor(h2, 'axes');
% Make the two axes have the same limits for easy comparison
If you flip back and forth between the two figures, you can see that the polyshape C plotted on the second figure is exactly the intersection between the two polyshape objects P1 and P2. If you want coordinates, use the Vertices property.
If you want to determine if an arbitrary point is inside the intersection, use isinterior.