Intersecting rectangles coordinates (one rectangle can be contained within the other)

I have 2 position vectors[x,y,width,height] representing 2 rectangles.If they are intersecting , what is the easiest method to find the coordinates of the intersected area.Is there a matlab function to do this ? I know rectint returns the area but i want the coordinates of the rectangle

[Dan]

use the bBoxOverlapRatio() function or portions of it if youd like.

Answer 1

[Kelly Kearney]

Assuming you already know the two polygons intersect, then you just need to compare where the left/right/bottom/top edges are:

r1 = [x1 y1 w1 h1];
r2 = [x2 y2 w2 h2];

l = max(x1,x2);
r = min(x1+w1,x2+w2);
b = max(y1,y2);
t = min(y1+h1,y2+h2);

r3 = [l r r-l t-b];

[vivek]

Thanks for the response.What I am trying to do is I have lets say n=100 rectangles.I want to find the combined overlapping area of all the rectangles.The rectangles as I mentioned can be contained within another rectangle.

[Kelly Kearney]

If you're interested in quantifying different amounts of overlap (for example, where exactly 3 polygons overlap, vs 2, 4, 5, etc), you might want to look at this function of mine: multiplepolyint.m. It might be overkill for axis-aligned rectangles, but it does the job pretty efficiently, especially with the fast flag turned on.

[Posada]

Thanks was helpful, but actually r3 should be: r3 = [l b r-l t-b];

Answer 2

[Brian Hannan]

I noticed from your comment above that you want to find the area of all of the intersecting rectangles rather than the coordinates of their intersection points. If that's the case, you can use polybool to do an AND operation on all of the polygons and then use polyarea to get the area of the result. This requires the mapping toolbox. If you don't have the mapping toolbox, you can use Emmett's Polygon Clipping and Offsetting filexchange submission .