[Insight-users] Problems dewarping a fluoroscopic image

[Boettcher, Dr. Peter]

I have serious problems dewarping a fluoroscopic image.

 

Following the examples of deformable image registration I construct a set of source and target landmarks. This is done by manual identification of the source landmarks (image grid of my fluo-image) and the corresponding points in my calibration grid. Using MeVisLab I can visualize the landmarks with their corresponding displacement vectors. As I set the image spacing to 1, I do not care about pixels ore world coordinates.

 

Resampling of my fluo-image is done as it is shown in LandmarksWarping2 example. I read in the landmarks, my fluo-image and compute the dewarped fluo image. However what I get is not what I expected. The image is less distorted than the original fluo-image, but one can see that there is still marked distortion within the image. 

A point which seems strange to me is the fact that the dewarped fluo image seems to be bigger than the original image. However all deformation is directed to the centre of the image, which should result in a shrunken image rather than an enlarged image.

 

 

 

I tried different kernels, I tried whether it would make any difference using itkWarpImageFilter or itkResampleImageFilter, I double checked the landmarks, but in the end I get the same result. 

 

I tried to look onto the deformation field - however the *.mda image which is generated using the code of the deformable registration examples does not make sense when I try to put some glyphs on it using ParaView. I suppose that only the x-values of the vectors provided within the mda-file are used.

 

 

Here are links to the different images I referred to within the mail.

 

Fluo image:http://www.bilder-upload.eu/show.php?file=lOAULD07LeTb0fZ.jpg

Grid: http://www.bilder-upload.eu/show.php?file=ON5DUNAnbRZaQ9w.jpg

Dewarped fluo image: http://www.bilder-upload.eu/show.php?file=F5KaxAcLLwbY1og.JPG

Source landmarks http://www.bilder-upload.eu/show.php?file=wcG9VZa0BapBS1k.jpg

Deformation field within MeVisLab http://www.bilder-upload.eu/show.php?file=iBrGaequ69018Re.jpg

Deformation field within Paraview http://www.bilder-upload.eu/show.php?file=9lKFQdamFMjR0In.jpg

 

 

 

Regards, Peter.

------------------------------------
Peter Böttcher, Dr med vet, DipECVS
European Veterinary Specialist in Surgery
Fachtierarzt für Kleintierchirurgie
Klinik für Kleintiere 
Universität Leipzig 
An den Tierkliniken 23 
D-04103 Leipzig (Germany)
Tel: +49-341-9738700 
Fax: +49-341-9738799
email: boettcher at kleintierklinik.uni-leipzig.de

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