Dear John and other users,
 
Thank you for your reply. Although I have carefully read the sections that you pointed to, I still have a problem since the result of that section is deformation not the flow field. I am doing Longitudinal dartel and I want to combine two warps.The result of the combination is going to be used in Normalize to MNI function in SPM8 as a flow field but if I understood correctly,the result of the compose function is deformation which can not be used as a flow field in Normalize to MNI function.right?
 
In short, I want to compose the flow field from within- subject DARTEL with flow field from between-subject DARTEL.The result should be in a format which could be used as a flow field for the final Normalize to MNI function!
Any suggestion would be highly appreciated!
 
Thanks in advance!
Kami
--- On Fri, 2/12/10, John Ashburner <[log in to unmask]> wrote:

From: John Ashburner <[log in to unmask]>
Subject: Re: Composition of two Dartel's flow fiels
To: [log in to unmask]
Date: Friday, February 12, 2010, 11:29 AM

Two deformation fields from Dartel can be composed, which allows the
image of one subject to be warped to match the image of another.  The
"Using DARTEL" chapter of the manual gives an example.

The flow fields themselves are not be composed - only the deformations
that are generated from them.  With a slightly different formulation of
the registration, it may be possible to appropriately combine initial
velocity fields using the Baker–Campbell–Hausdorff formula.  I could be
wrong here though.

Best regards,
-John

On Fri, 2010-02-12 at 07:40 -0800, kambiz rakhshan wrote:
> Dear all,
> 
> Is there any function in SPM which only compose two flow fields
> extracted from Dartel? I don't want to apply it to an image in this
> stage, but instead later on in normalize to MNI as a flow field?
> 
> 
> 
> Best
> Kami
>


--
John Ashburner <[log in to unmask]" ymailto="mailto:[log in to unmask]">[log in to unmask]>