How do you create delaunay triangulation for random points inside a polygon
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I am having a very hard time trying to create a delaunay triangulation constrained by the borders of the provided polygon using the random points generated inside of my polygon. Provided below is my attempt, however I feel I a far from correct. (I also received help on this code below to get to where I am at now) Thank you!
states = shaperead('usastatehi.shp');
st = states(47); %creates a polgon in the shape of Washington State
stBB = st.BoundingBox;
st_minlat = min(stBB(:,2 ));
st_maxlat = max(stBB(:,2 ));
st_latspan = st_maxlat - st_minlat;
st_minlong = min(stBB(:,1 ));
st_maxlong = max(stBB(:,1 ));
st_longspan = st_maxlong - st_minlong;
stX = st.X ;
stY = st.Y;
numPointsIn = 42;
for i = 1:numPointsIn
flagIsIn = 0;
while ~flagIsIn
x(i) = st_minlong + rand(1) * st_longspan ;
y(i) = st_minlat + rand(1) * st_latspan ;
flagIsIn = inpolygon(x(i), y(i), stX, stY );
end
end
mapshow(st, 'edgecolor', 'r', 'facecolor', 'none ')
hold on
scatter(x, y , '.')
dt = delaunayTriangulation(x(i),y(i))
hold on
3 Comments
Accepted Answer
KSSV
on 30 Nov 2017
states = shaperead('usastatehi.shp');
st = states(47); %creates a polgon in the shape of Washington State
stBB = st.BoundingBox;
st_minlat = min(stBB(:,2 ));
st_maxlat = max(stBB(:,2 ));
st_latspan = st_maxlat - st_minlat;
st_minlong = min(stBB(:,1 ));
st_maxlong = max(stBB(:,1 ));
st_longspan = st_maxlong - st_minlong;
stX = st.X ;
stY = st.Y;
numPointsIn = 42;
for i = 1:numPointsIn
flagIsIn = 0;
while ~flagIsIn
x(i) = st_minlong + rand(1) * st_longspan ;
y(i) = st_minlat + rand(1) * st_latspan ;
flagIsIn = inpolygon(x(i), y(i), stX, stY );
end
end
mapshow(st, 'edgecolor', 'r', 'facecolor', 'none ')
hold on
scatter(x, y , '.')
dt = delaunayTriangulation(x',y') ;
hold on
triplot(dt) ;
If your idea is to m esh the entire region......then you should have a look here: https://in.mathworks.com/matlabcentral/fileexchange/25555-mesh2d-delaunay-based-unstructured-mesh-generation
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