thank you, John, that was very helpful. if everything would be so
easy in life...
bye, pisti
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On Mon, 11 Feb 2008, John Ashburner wrote:
>
> Here is a snippet of MATLAB code that may be informative:
>
>>> M = [-1.9945 -0.0499 -0.1399 70.8144
> -0.0891 1.9090 0.5896 -63.5382
> -0.1188 -0.5942 1.9060 -60.7934
> 0 0 0 1.0000];
>>>
>>> sqrt(sum(M(1:3,1:3).^2))
>
> ans =
>
> 2.0000 2.0000 2.0000
>
>>> svd(M(1:3,1:3))
>
> ans =
>
> 2.0000
> 2.0000
> 2.0000
>
>>>
>
> And for figuring out if there is a flip, the following gives the volume of a
> voxel:
>
>>> det(M(1:3,1:3))
>
> ans =
>
> -8.0000
>
>
> Best regards,
> -John
>
> On Monday 11 February 2008 06:01, Istvan Akos Morocz wrote:
>> dear SPM list,
>>
>> here a quite silly question: how can one determine the correct voxel
>> size in a given MRI volume in SPM5, for example by using spm_vol.m
>> (like previously with SPM2). V.mat doesn't lead anymore to the
>> desired information., like in the past by computing :
>>
>> myVox = abs([ V.mat( 1, 1) V.mat( 2, 2) V.mat( 3, 3) ]) ;
>>
>> for example, i expect to deal with 2x2x2mm, but Y.mat instead gives:
>>
>> -1.9945 -0.0499 -0.1399 70.8144
>> -0.0891 1.9090 0.5896 -63.5382
>> -0.1188 -0.5942 1.9060 -60.7934
>> 0 0 0 1.0000
>>
>> that's now after rotation i guess (as no mat files anymore). looked
>> through the codes and also in the archives - w/o prevail.
>>
>>
>> thanks in advance, bye,
>>
>> pisti
>>
>>
>> -----
>> www.pistikem.org
>> [log in to unmask]
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