AFNI Message Board

Dear AFNI users-

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.

Sincerely, AFNI HQ

History of AFNI updates  

Previous Message Next Message
Message List New Topic Print View
|
Jim Bjork
November 10, 2003 12:32PM
Hello,

The 3dMerge manual descibes the smoothing performed by

-1blur_fwhm bmm

as an "isotropic Gaussian blur." We found that specifying bmm as 4.0 (mm) was optimal in our maps. However, our slice thickness is 2.0 mm, with the inplane resolution of the GE EPIRT on 3T-1 as 3.75 X 3.75. Thus, the through-plane resolution is roughly double the in-plane since our voxels are non-isotropic.

What is AFNI doing in this instance (assuming "isotropic" in the manual implies smoothing in all three directions)? Is it incorporating data from almost twice as many neighboring voxels through-plane as from within-plane?

I need this information in order to properly calculate "resels".

Jim B

Reply Quote
RSS
Subject Author Posted

Isotropic smoothing across non-isotropic voxels

Jim Bjork November 10, 2003 12:32PM

Re: Isotropic smoothing across non-isotropic voxels

bob cox November 10, 2003 12:53PM