[Insight-users] Convert image distance into physical space

[Cory Quammen]

To do as Dženan recommends, the following may be useful to know.

Here's my understanding of ITK's mapping from index space to physical
space. Someone please correct my if I am wrong!

For each dimension, the physical position of a voxel's center given an
index is computed as

xyz[i] = origin[i] + spacing[i]*index[i]

where i is a particular image dimension, xyz is the position, origin
is the origin of the image, and spacing is the spacing between
adjacent voxels. This assumes that the image has the default
orientation.

See page 40 of the ITK Software guide (
http://www.itk.org/ItkSoftwareGuide ) for more details of how ITK
defines an image.

As a convenience, you can use the method
itk::Image::TransformIndexToPhysicalPoint() to convert between a voxel
index and a physical location.

Cory

On Thu, Sep 20, 2012 at 10:09 AM, Dženan Zukić <dzenanz at gmail.com> wrote:
> There is no correct answer. You can however approximate it by multiplying
> with cubicroot(0.5x0.5x1)=0.6299...
>
> To get correct answer, you need to calculate Euclidean distance in physical
> space.
>
> On Thu, Sep 20, 2012 at 2:56 PM, drrk <rashed.karim at gmail.com> wrote:
>>
>> If the resolution of a 3D image is 0.5 by 0.5 by 1 mm. And I compute
>> Euclidean distances on the image's voxel space. So lets say a distance of
>> 10
>> in the voxel space, what is its equivalent in the physical space?
>>
>>
>>
>>
>>
>> --
>> View this message in context:
>> http://itk-users.7.n7.nabble.com/Convert-image-distance-into-physical-space-tp29529.html
>> Sent from the ITK - Users mailing list archive at Nabble.com.
>> _____________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Kitware offers ITK Training Courses, for more information visit:
>> http://www.kitware.com/products/protraining.php
>>
>> Please keep messages on-topic and check the ITK FAQ at:
>> http://www.itk.org/Wiki/ITK_FAQ
>>
>> Follow this link to subscribe/unsubscribe:
>> http://www.itk.org/mailman/listinfo/insight-users
>
>
>
> _____________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
> Kitware offers ITK Training Courses, for more information visit:
> http://www.kitware.com/products/protraining.php
>
> Please keep messages on-topic and check the ITK FAQ at:
> http://www.itk.org/Wiki/ITK_FAQ
>
> Follow this link to subscribe/unsubscribe:
> http://www.itk.org/mailman/listinfo/insight-users
>



-- 
Cory Quammen
Research Associate
Department of Computer Science
The University of North Carolina at Chapel Hill