[Insight-users] Re: [vtkusers] pixel data at world position

[Renaud Isabelle]

Hi Mark,
 
Thanks for replying. 
 
I have already computed my world position by firing a picker from pixel coordinates. Sorry but I don't see or know what the mapper coordinates are. What is the difference and how this could help me to retrieve the index in my itkImage's buffer corresponding to my world position?  
 
BTW, what is your '+ 0.5'? I suppose this is the origin in x of your image, right? 
 
Isabelle

Mark Wyszomierski <markww at gmail.com> a écrit :
You can fire a pick event when the user clicks the mouse:
 
    Picker->Pick(eventpos[0], eventpos[1], 0, renderer);
    
Then you can get the mapped position:
 
    Picker->GetMapperPosition(...);
 
Then  the final x,y locs of the original image I get by:
 
    originalX = (int)(ptMapped[0] / pixel_spacing_x + 0.5);
    // same for y.
 
This always has given me the correct 'real' location.
 
Mark

 
On 10/5/05, Renaud Isabelle <renauisa at yahoo.fr> wrote: Hi all,
 
I have read an initial 3D image from a file with itkImageFileReader and displayed with VTK through vtkImageData/vtkImageActor.
 
Now, since a known world position in 3D x,y,z, I would like to retrieve the pixel value at this point of my image. 
 
This seems to be a complex problem, because I don't want the pixel data that is displayed at this position but the pixel data of the raw image, that is no rescaled instead.
 
Is there some example where such a thing is done? Or any function? 
 
Thanks, 
 
Isabelle
 
   
 
 


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