On 25 Nov 2006, at 15:08, Bruce Fischl wrote:
Hi Roberto,
no, nothing built in, but you could always mask it to the label in matlab. I guess we could provide an mris_mask utility if that would be helpful.
thanks Bruce,
I've been trying to compute the folding index (FI) based on the max/ min files generated by mris_curvature, but I'm obtaining different values . When I load a surface the np vertices are in p[], the nt triangles in t[], then max/min curvatures are in max[] and min[] respectively. This is what I'm doing next
FI=0; for(i=0;i<nt;i++) { //triangle vertices' indices i0=t[3*i+0]; i1=t[3*i+1]; i2=t[3*i+2]; // triangle area area=triangle_area(&p[3*i0],&p[3*i1],&p[3*i2]); // FI at the vertices fi0=fabs(max[i0])*(fabs(max[i0])-fabs(min[i0])); fi1=fabs(max[i1])*(fabs(max[i1])-fabs(min[i1])); fi2=fabs(max[i2])*(fabs(max[i2])-fabs(min[i2])); // integration of FI over the triangle FI+=area*(fi0+fi1+fi2)/3.0; } FI=FI/(float)(4*3.141592653589793);
for every triangle the algorithm computes the value of FI at the vertices and integrates over the triangle. The values I'm obtaining are larger than those reported by mris_curvature (4585 instead of 2537, or 4408 instead of 2750, for example). Furthermore, in the paper where Van Essen introduces the FI, he reports a value of 510 for a hemisphere of the Visible Man! Is there something tha I'm missing?
thanks in advance! roberto
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