[vtkusers] ] How to get the right 3D world position for the 2d

[Richard Frank]

> 
> Hi,
> 
> In our application, we have 3 2d views using vtkImageViewer2 to display
the
> sagittal, coronal and axial view of the DICOMs, and we have another view
for
> the generated 3D model. Now I want to achieve the requirement below:
> 
> If user click a point on one slice on the 2D view, I need to get the
> corresponding 3D point on the 3D model view.
> If user click a point on the 3D model view, I need to get the
corresponding 2D
> point and slice number.
> 
> How to achieve that?
> 
> Thanks
> tjlp

Depending on how you load the data into the vtkImage, you will need to map
from voxel space (I,j,k) to patient space (L,P,S, or R,A S)

In general, you will use Equation C.7.6.2.1-1. 

As seen here

http://dicom.nema.org/medical/dicom/current/output/html/part03.html#sect_C.7
.6.2.1.1

The equation doesn't show Z or k values, so you would have to consider them
(the Z direction cosines vector, and the k value in the image volume) as
part of a 3 dimensional mapping.

HTH

Rick Frank
Dominion Software, Inc.
www.dominionsw.com