MATLAB: How to calculate Area of overlapping polygons inside square

areaMATLABoverlappolygon

I have requirement to calculate percentage of area covered by polygons inside square(Green Border) for matlab plot.

Logic used is Area coverage= Area of outer square- area of each polygon- polygon overlapping area

I am stuck at finding overlapping area as there are more than 3 polygons overlapping. I am using intersect function for finding intersection

Is there any better method for this requirement(Can Non-plotted are be measured?)

Best Answer

Take the union of all the polyshape objects representing your polygons

Make a polyshape representing the interior and boundary of your square and intersect that square with the union polyshape.

This results in one final polyshape whose area you can compute.

Related Solutions

MATLAB: Area of intersection between a circle and polygon

One possible way is generating intersection by intersect function, and calculate it's area by area function. The following is an example.

x = 0; y = 0; r = 0.5;  
th = 0:pi/50:2*pi;
xunit = r * cos(th) + x;
yunit = r * sin(th) + y;
poly0 = polyshape(xunit(1:end-1),yunit(1:end-1));
poly1 = polyshape([0 0 1 1],[1 0 0 1]);
poly2 = intersect(poly0,poly1);
area(poly2)

The result is:

>> area(poly2)
ans =
  0.1962

MATLAB: Union of polyshapes ignoring empty ones

When given an array of polyshape objects, area returns an array of the same size. This means you can use it for logical indexing.

A = area(poly1);
U = union(poly1(A > 0))
area(U)

You could encapsulate the union-skipping-empties step into your own function.

function outputPolyshape = unionSkippingEmpties(inputPolyshapes)
A = area(inputPolyshapes);
outputPolyshape = union(inputPolyshapes(A > 0));
end

You could even have this accept a threshold for what counts as an "empty" / "trivial" polyshape that should be excluded from the union.

Best Answer

Related Solutions

MATLAB: Area of intersection between a circle and polygon

MATLAB: Union of polyshapes ignoring empty ones

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