Intersecting and non-intersecting box regions

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Elysi Cochin
Elysi Cochin on 10 Jul 2021
Commented: Matt J on 12 Jul 2021
Having a set of bounding box values [x y width height] , how can i find the number of bounding box that gets intersected and that do not gets intersected when plotted
From the above example, there are 5 intersecting boxes and 2 non-intersecting boxes
How can i do so with the attached bounding box values

Accepted Answer

Matt J
Matt J on 10 Jul 2021
Edited: Matt J on 10 Jul 2021
Using rectint(), you can straightforwardly obtain a binary mask A such that A(i,j)=1 if rectangle bbx(i,:) and bbx(j,:) intersect.
load bbx
A=rectint(bbx,bbx)>0
A = 20×20 logical array
1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0
and therefore the number of rectangles that have an intersection another rectangle would be,
N=sum(tril(A,-1),'all')
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More Answers (2)

Simon Chan
Simon Chan on 10 Jul 2021
If viusal inspection is allowed, then the number can be counted by plotting the boxes in a figure:
rawdata=load('bbx.mat');
figure
for k=1:length(rawdata.bbx)
rectangle('Position',rawdata.bbx(k,:))
end
  4 Comments
Simon Chan
Simon Chan on 10 Jul 2021
Would you please run the following commands before the above script:
clear;
clc;
If the error happens again, would you please run the following:
size(A) % Check the dimension of Matrix A
size(B) % Check the dimension of Matrix B

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KSSV
KSSV on 10 Jul 2021
Run a loop for each box and find the intersection points. Use this to get the intersection points.
If your output is empty, it means there is no intersection.
  3 Comments
Elysi Cochin
Elysi Cochin on 10 Jul 2021
i didnt get that Sir. Please can you show me an example?

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