How to rotate a polygon

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Md 2015-5-14

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回答： Walter Roberson 2015-5-15

Hi, I have some data points that forms a irregular shape polygon. I want to rotate the polygon gradually to see the minimum area bounded by a rectangle for the polygon. Can anyone help me in this ..... Thanks in advance.

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Dasharath Gulvady 2015-5-15

You may use "hgtransform" and rotate the irregular shaped polygon. Refer the examples in the documentation page below:

http://www.mathworks.com/help/matlab/ref/hgtransform.html

For the second part of the question - "to see the minimum area bounded by a rectangle for the polygon", can you elaborate more on this?

Walter Roberson 2015-5-15

Please do not tag individuals. http://www.mathworks.co.uk/matlabcentral/answers/43073-a-guide-to-tags

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Answer 1

Walter Roberson 2015-5-15

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To find the minimum area bounded by a rectangle for the polygon, start by finding the furthest distance between any two points on the polygon. The pair of points with the furthest distance forms one axis of a bounding rectangle. Rotate the polygon so that the pair is along the vertical axis, and then the distance between the maximum and minimum horizontal axis results will give you the length of the smaller side.

There might be a nice vector algebra way of doing this; I don't know.

The MajorAxisLength and MinorAxisLength of regionprops() might help.