How to calculate the rotation of this egg?

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Ashfaq Ahmed
Ashfaq Ahmed 2022 年 8 月 9 日
コメント済み: Matt J 2022 年 8 月 9 日
Hi all!
Suppose I have this egg in figure1, standing still. But when it rotates a bit in figure 2, how can I calculate the rotation angle using MATLAB coding? Can anyone please give an idea on it?
I have attached the images in the question. (egg1, and egg2). Any suggestion from you will be much appreciated ^_^

採用された回答

John D'Errico
John D'Errico 2022 年 8 月 9 日
  1. Find a bounding box, where the box can be rotated, not a box that is aligned with the axes.
  2. Find the orientation (angle of inclination) of the long sides of the bounding box. atan2 will help you there.
  3. Nothing more needed, since atan2 did all the work.
  2 件のコメント
John D'Errico
John D'Errico 2022 年 8 月 9 日
編集済み: John D'Errico 2022 年 8 月 9 日
I'm sure the Image processing toolbox has a bounding box utility. (I'll find it in a minute or so, and post the link too.) But you can also extract the points as a set of pixel locations, and then use my minboundrect utility.
Ok. A quick search tells me the tool is regionprops. It looks like you need to do something like:
regionprops(egg2,'boundingbox')
Lacking the IPT, I've never used it, but one of those tools will get you there.

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その他の回答 (2 件)

Matt J
Matt J 2022 年 8 月 9 日
編集済み: Matt J 2022 年 8 月 9 日
First, crop the black corders from your image fiels. Then, use ellipticalFit() from,
getEgg=@(file) imbinarize(im2gray(imread(file)));
[Y1,X1]=find(edge(getEgg('egg1.png')));
[Y2,X2]=find(edge(getEgg('egg2.png')));
fobj1=ellipticalFit([X1(:),Y1(:)]');
fobj2=ellipticalFit([X2(:),Y2(:)]');
rotation = fobj2.angle-fobj1.angle
rotation =
137.9371
function out=getEgg(file)
out=imbinarize(im2gray(imread(file)));
end
  3 件のコメント
Ashfaq Ahmed
Ashfaq Ahmed 2022 年 8 月 9 日
This code works perfectly! Thank you so much!!

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Matt J
Matt J 2022 年 8 月 9 日
BW1=~getEgg('egg1.png');
BW2=~getEgg('egg2.png');
S1=regionprops(BW1,'Orientation');
S2=regionprops(BW2,'Orientation');
rotation = S2.Orientation-S1.Orientation
rotation = -137.9439
function out=getEgg(file)
out=imbinarize(im2gray(imread(file)));
end
  2 件のコメント
Matt J
Matt J 2022 年 8 月 9 日
The difference is 0.007 degrees. I'm surprised that it would be considered significant.

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