Order of coefficients in the file `SPHARM.coef`

[Matheus Viana]

Hi.

I was wondering in which order the coefficients are saved in the xx_SPHARM.coef files. Sorry, I couldn't find it anywhere.

Thanks,

[Martin Styner]

Hi Matheus, quick comment first: this is the issue tracker not the help forum. As SPHARM-PDM is part of SlicerSALT, the best place for help is on the SlicerSALT forum: https://discourse.slicer.org/c/community/slicer-salt

Information about the coefficients can be found here:

1. Styner M, Oguz I, Xu S, Brechbühler C, Pantazis D, Levitt JJ, Shenton ME, Gerig G. Framework for the Statistical Shape Analysis of Brain Structures using SPHARM-PDM. Open Science Workshop at MICCAI - Insight Journal. 2006. PMCID: PMC3062073

The order in the file is best described through the GetCoefAt function (coord is one of the 3 coordinates that are fitted via the spherical harmonics):
GetCoefAt(unsigned int l, unsigned int m, unsigned int coord, double *coef)
{
if( m == 0 )
{
coef[0] = m_Coefs[l * l][coord];
coef[1] = 0;
}
else
{
coef[0] = m_Coefs[l * l + 2 * m - 1][coord];
coef[1] = m_Coefs[l * l + 2 * m][coord];
}
}

[David Allemang]

Closing since this is not an issue with the code, and there has been no activity for a while.