Selecting data within a particular shape from a matrix.
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Hi,
I want to select data around point [169,547] in the attached v variable. Attached is the figure of the shape in which I want the coordinate values, their distance and angle with respect to the center point [169,547]. The case represents a dynamic crack which moves forward in the next frame and thus the center position will change in the next frame and the whole process will be repeated again. Any guidance regarding the implementation would be great.
Cheers
Waqas
댓글 수: 4
Image Analyst
2019년 8월 31일
His coordinate is probably (x, y) not (row, column), so the matrix should exist at row 169, column 547 in a matrix of 304 rows and 640 columns.
Matt J
2020년 7월 22일
waqas commented:
Hi,
I started a new question which is on the same lines as this question. It would be interesting to hear from you guys about that! I tried to figure it out by my own but am unable to get exactly what I want to.
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Matt J
2019년 8월 31일
편집: Matt J
2019년 8월 31일
As an example,
xc=547; yc=169; %center coordinates
rint=10; rext=50; %internal and external radii
[X,Y]=meshgrid((1:size(v,2))-xc, (1:size(v,1))-yc );
crack= Y<=rint & Y>=-rint & X<=sqrt(rint^2-Y.^2);
region= X.^2+Y.^2<=rext^2 & ~crack;
selected_data = v(region);
imshow(region);
댓글 수: 10
Matt J
2019년 10월 7일
편집: Matt J
2019년 10월 7일
If you know the inclineAngle, it should be a 2-line modification,
[X,Y]=meshgrid((1:size(v,2))-xc, (1:size(v,1))-yc );
[Theta,Rho]=cart2pol(X,Y);
[X,Y]=pol2cart(Theta+inclineAngle, Rho);
crack= Y<=rint & Y>=-rint & X<=sqrt(rint^2-Y.^2);
region= X.^2+Y.^2<=rext^2 & ~crack;
selected_data = v(region);
imshow(region);
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