We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:
https://discuss.afni.nimh.nih.gov
Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.
The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.
In your 64x64x50 example, voxel (i,j,k) is stored in row number i+64*j+64*50*k for i=0..63, j=0..63, k=0..49, where row numbers start counting at 0, of course. That is to say, the first index varies most rapidly, then the second, and the third index the slowest. This maps directly to the way that AFNI stores 3D volume images.