[Insight-users] confusion between pixels and indexes in digitally reconstructed radiographs

[Moti Freiman]

Hello,

I'm trying to generate digitally reconstructed radiographs (DRRs) using 
the itkImageResample filter with itkRescaleIntensityImageFilter.  For a 
first trial i used the program:

DigitallyReconstructedRadiograph1 supplied with the itk distribution.
When i tried to create drr with the default volume created in that 
program, i go t some image.
Then, i set the translation in the x axis to 10 (i assume millimeters), 
and create another drr.
The default spacing of the drr is 1.mm in both x,y axis.
Therefore i excepted from the image to move exactly in 10 pixels.
But, when i opened the images in matlab i found that it moves in almost 
30 pixels.
One issue that may be related to that is that the volume which the drr 
generated from has a spacing of 3mm.
It seems that the setting of the camera transform to the ray cast 
interpolator cause some confusion or bug, between the volume spacing and 
drr spacing.

I'll appreciate very much any help in that problem.
Moti

In order to demonstare the problem i used the default volume created in  

-- 
__
Moti Freiman, Ph.D Student.
Medical Image Processing and Computer-Assisted Surgery Laboratory.
School of Computer Science and Engineering.
The Hebrew University of Jerusalem Givat Ram, Jerusalem 91904, Israel
Phone: +(972)-2-658-5371 (laboratory)
E-mail: freiman at cs.huji.ac.il
WWW site: http://www.cs.huji.ac.il/~freiman