Filtering with Nonlinear Anisotropic Diffusion (NAD)

(IMOD 4.9)

University of Colorado, Boulder


This tutorial will guide you through filtering a cryo data set with Nonlinear Anisotropic Diffusion (NAD). Filtering with NAD is relatively slow and involves adjusting two parameters to give the desired amount of filtering.  The strategy is to do the operation on a small test volume and compare the results from different parameter settings in order to pick the right setting.  After that, the full volume is filtered by breaking it into chunks so that multiple processors can be used. 


Filtering is done with the program nad_eed_3d, contributed to IMOD by Frangakis and Hegerl.  The man page for that program has a bit more information and a reference to their paper.


Getting started:

Extracting the Test Volume:

Finding K Value for the Test Volume:

Finding Iteration Number for the Test Volume:

Filtering the Full Volume: