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How can i draw a slanted rectangle in a frame?

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Maayan
Maayan on 12 Sep 2013
I have a code that takes a video,split it into frames and then asks me how many rectangles would i like to draw on the frame (the first one). In those rectangles the mean intensity in each frame is calculated.I would like to be able to draw a slanted rectangles too.Is there any command that can help me?Here is the part of my code that is responsible for making the rectangles:
if k==1
result=input('How many rectangles would you like to draw? ');
pos=zeros(result,4);
for i=1:result
handle=imrect;
pos(i,:)=handle.getPosition;
end
end

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Accepted Answer

Image Analyst
Image Analyst on 12 Sep 2013
You could call the line() command 4 times to draw the sides of your slanted rectangle in the graphical overlay above the image. Alternatively, if the user needs to adjust the vertices, you can call impoly().

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Image Analyst
Image Analyst on 15 Sep 2013
By making sure that you have 4 vertices at 90 degrees to each other.
Maayan
Maayan on 15 Sep 2013
Yes i know that's the way to draw a rectangle,but i'm doing it by hand with the impoly() command. How can i know for sure? Is there any way to restrict the impoly() command?On the other hand,Is there any way to draw a rectangle with the imrect() command and to rotate it?
Image Analyst
Image Analyst on 15 Sep 2013
Sure. You know the rotation matrix, I'm sure. In case you don't, it's [cos(theta), sin(theta); -sin(theta), cos(theta)]. Just multiply your 4 by 2 array of (x,y) coordinates by that. Be sure to offset the coordinates by the center of the rectangle if you want to rotate it about the center of the rectangle rather than the origin!!

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