.. ah yes, that was bound to happen: I got ahead of myself and did not
read properly enough. So yes, in the case of mm coordinates and the
coordinates only differing in one plane, the answer in fact is yes. The
sum of absolute difference between two sets of 3D coordinates is not
usually the Euclidian distance between them, but of course I had to talk
big on one of the exceptions. Apologies for being too quick.
Cheers,
Marko
John Ashburner wrote:
>>> In this regard, suppose we have 2 voxels whose MNI coordinates are (1 2
>>> 3) and (2 2 3). Is the distance between the two 1mm?
>
>> The answer is no
>
> Actually Marko, I think the answer is yes (as they are MNI
> coordinates, which are in mm)..
>
> v1 = [1 2 3];
> v2 = [2 2 3];
> distance = norm(v2-v1)
>
> Best regards,
> -John
>
> On 27 June 2012 07:34, Marko Wilke <[log in to unmask]> wrote:
>> Ce,
>>
>>
>>> Thank you very much for your response, Dr Mclaren.
>>
>>
>> I'll answer for Donald so he gets a break ;)
>>
>>
>>> In this regard, suppose we have 2 voxels whose MNI coordinates are (1 2
>>> 3) and (2 2 3). Is the distance between the two 1mm?
>>
>>
>> The answer is no: you are looking at a distance in 3D, for which you will
>> have to calculate the Euclidian distance. In order to obtain this, you may
>> want to you play with an extension of Pythagoras' theorem to get the length
>> of the vector between two points in space. In other words, "the length of
>> the vector results from the square root of the sum of squared translations
>> in each dimension". See PMID 22036679.
>>
>> Cheers,
>> Marko
>> --
>> ____________________________________________________
>> PD Dr. med. Marko Wilke
>> Facharzt für Kinder- und Jugendmedizin
>> Leiter, Experimentelle Pädiatrische Neurobildgebung
>> Universitäts-Kinderklinik
>> Abt. III (Neuropädiatrie)
>>
>>
>> Marko Wilke, MD, PhD
>> Pediatrician
>> Head, Experimental Pediatric Neuroimaging
>> University Children's Hospital
>> Dept. III (Pediatric Neurology)
>>
>>
>> Hoppe-Seyler-Str. 1
>> D - 72076 Tübingen, Germany
>> Tel. +49 7071 29-83416
>> Fax +49 7071 29-5473
>> [log in to unmask]
>>
>> http://www.medizin.uni-tuebingen.de/kinder/epn/
>> ____________________________________________________
>
--
____________________________________________________
PD Dr. med. Marko Wilke
Facharzt für Kinder- und Jugendmedizin
Leiter, Experimentelle Pädiatrische Neurobildgebung
Universitäts-Kinderklinik
Abt. III (Neuropädiatrie)
Marko Wilke, MD, PhD
Pediatrician
Head, Experimental Pediatric Neuroimaging
University Children's Hospital
Dept. III (Pediatric Neurology)
Hoppe-Seyler-Str. 1
D - 72076 Tübingen, Germany
Tel. +49 7071 29-83416
Fax +49 7071 29-5473
[log in to unmask]
http://www.medizin.uni-tuebingen.de/kinder/epn/
____________________________________________________
|