Dear Matt,
Skews are not rotations.
To get the rotation angles you need to use the --allparams option
to avscale. It will display the rotation angles in radians (which
it states in the output).
All the best,
Mark
On 5 Feb 2007, at 16:50, Matt wrote:
> Mark,
>
> I want to know the rotations in the xy, xz, and yz planes in
> degrees so I
> can use these numbers to rotate a gradient file (I already have an
> excel
> sheet that does this). How should I convert the numbers output by
> avscale
> to degrees?
>
> Thanks for your help,
>
> Matt.
>
> -----Original Message-----
> From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On
> Behalf
> Of Mark Jenkinson
> Sent: Monday, February 05, 2007 11:23 AM
> To: [log in to unmask]
> Subject: Re: [FSL] Flirt Transformation Matricies
>
> No.
> They are elements of the off-diagonal terms of a skew matrix and
> are therefore dimensionless.
> All the best,
> Mark
>
>
> Matt wrote:
>
>> Mark,
>>
>> Am I correct in assuming the following values are in radians?
>> Skews (xy,xz,yz) = -0.002712 0.010341 0.043795
>>
>> Thanks,
>>
>> Matt.
>> -----Original Message-----
>> From: FSL - FMRIB's Software Library [mailto:[log in to unmask]]
>> On Behalf
>> Of Mark Jenkinson
>> Sent: Monday, February 05, 2007 3:08 AM
>> To: [log in to unmask]
>> Subject: Re: [FSL] Flirt Transformation Matricies
>>
>> You can get *a* decomposition into angles using avscale.
>> However, such decompositions are not unique (there are lots of
>> arbitrary choices) so beware if you intend to compare these
>> with anything else.
>>
>> All the best,
>> Mark
>>
>>
>> On 5 Feb 2007, at 06:53, Matt Glasser wrote:
>>
>>
>>
>>> I would like to know the number of degrees of yaw, pitch, and roll
>>> transformation of any given flirt transformation matrix. Could
>>> someone
>>> explain what the numbers in the matrix mean, or point me towards
>>> some
>>> documentation that does?
>>>
>>> Thanks!
>>>
>>> Matt.
>>>
>>>
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