How do I make 3D sphere for convolution?
25 visualizzazioni (ultimi 30 giorni)
Mostra commenti meno recenti
Hi all,
I want to make a 3D sphere where the x, y and z coordinates are being solved in a 3D array, so I can convolute this with a kernel I have. But, I don't seem to both save the coordinates and get the shape right at the same time. I have the following code:
figure;
half=50;
for k=1:100
for j=1:100
for i=1:100
mesh_sphere(i,j,k)=((i-half).^2)+((j-half).^2)+((k-half).^2);
end
end
surf(mesh_sphere(:,:,k));
hold on
end
hold off
After this, I also want to use other shapes that I can test my kernel on, such as a hollow sphere and an ellipsoid. How can I make those and also same them in a 3D array? Thank you in advance!
0 Commenti
Risposta accettata
Rik
il 12 Gen 2022
If you want a sphere in a 3D array, you should probably do something like this:
array_width=21;%must be odd
radius=5;%must be smaller than half the array width for the sphere to fit
a=(array_width-1)/2;
a=linspace(-a,a,array_width);
[X,Y,Z]=meshgrid(a);
solid_sphere= sqrt(X.^2 + Y.^2 + Z.^2) <= radius;
For a shell you can repeat this with two radii and use the or operator |. For an elipsoid you need you can scale the coordinate values in each direction according to the partial radius you want.
9 Commenti
Image Analyst
il 13 Gen 2022
Modificato: Image Analyst
il 13 Gen 2022
@Lieke Pullen like I showed in my answer below, the strel() function creates the sphere in one line of code. The convolution is also done in one line of code.
Più risposte (1)
Image Analyst
il 12 Gen 2022
Modificato: Image Analyst
il 13 Gen 2022
SE = strel('sphere',r) % creates a 3-D spherical structuring element whose radius is r pixels.
out = convn(inputImage, SE.Neighborhood);
3 Commenti
Rik
il 12 Gen 2022
I don't remember this object notation. Admittedly, I haven't used this function in years, but I will look up this function in the release notes to see whether I forgot, or if they changed it.
Vedere anche
Categorie
Scopri di più su Matrix Indexing in Help Center e File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!