Use coefficients to reconstruct

Community SlicerSALT
1

I applied SHPARM-PDM extension, and then obtained the coefficients of spherical harmonic.
I wonder if I can reconstruct the original mode by just use the coefficients.

2

Yes, you can. You need to sample the spherical parametrization space and then evaluate the spherical harmonic series at those sample. SlicerSALT is doing that already for you, by using a spherical sampling scheme based on an icosahedron subdivision. The tool that does this is called ParaToSPHARMPDM, which first fits the coefficients and then generates a reconstructed surface from those coefficients.

Martin

3

Dear Martin,

Thank you for your response.

Actually, I have tried to reconstruct the shapes by the output the spherical harmonic coefficients
.

Just generated the series of spherical harmonics for each v(phi, theta), and then multiply the coefficients.

However, the result shape is just like a surface.

Because I am trying to develop a tool to apply the spherical harmonic coefficients
.

I wonder if I miss any other parameters.

Cheng

Martin Styner via 3D Slicer Community slicer@discoursemail.com 於 2019年10月25日 週五 上午4:40寫道：

4

Not sure what may be wrong in your reconstruction code, but you can look at the code in SlicerSALT:
surface reconstruction:

SPHARM reconstruction at phi/theta:


(look at function Evaluate)

Martin

5

Dear Martin,

Thanks a lot.

Originally, I implemented my code by Python and apply scipy.special.sph_harm and np.linalg.lstsq to solve the coefficients.

It might have some differences in the details.

I think I can start to modify my code by reference your code.

Regards

Cheng

Regards

Cheng

Martin Styner via 3D Slicer Community slicer@discoursemail.com 於 2019年10月25日 週五 下午10:52寫道：