how can i extract data between 4 points in a matrix?

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Maayan 2013-10-1

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评论： Maayan 2013-10-1

I have a matrix and 4 vertices of a rectangle. The rectangle is not aligned with the axes,i.e the rectangle is slanted. I want to extract the data between the 4 vertices into a new matrix. How can i do it? I've been trying to do it for weeks. Thanks

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Answer 1

Image Analyst 2013-10-1

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Weeks? Wow. Do yo have the Image Processing Toolbox? If so, you can simply use poly2mask():

[rows, columns] = size(your2Darray);
logicalMap = poly2mask(x, y, rows, columns); % put in coords of the rectangle corners.
extractedValues = your2Darray(logicalMap);

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Maayan 2013-10-1

Yes weeks,I know it's a long time- I'm new with programming codes and i'm new with matlab. In your second line you wrote columns and rows- do you mean the number of columns and rows in my rectangle? All i have is the 4 vertices of the slanted rectangle so i don't know how to calculate the number of columns and rows in it.

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