[vtkusers] volume rendering of medical data

[Thomas Faust]

I did exactly the same thing. Picking in a 3D model ist quite tricky. To get a 
point on the boundary box of the volume is easy. But most likely, the first 
layers of your model are air and you want to select pickels on the surface of 
your model, right?

Here is, what I did. Derivate a calss from vtkPicker and overwrite the 
function IntersectWithLine(). This function gets an ray form the camera to 
your picked point in space as input variables, which is already cut at the 
clipping ranges.
From now on its math, but straigth forward. Look for the entry point of the 
ray in your volume. (this you can do by vtkCell::HitBBox or with 
vtkBox::IntersectBox in newer VTK versions)
Then use an 'voxel traversal algorithm' to travel through the voxels and find 
the one that is part of your interest, store the value in your picker and 
'mark as picked'

That's about it. Have fun.

On Thursday 27 May 2004 04:05 am, Chandna, Sandeep (Research, Non-ge) wrote:
> Hi,
> 	I am doing a project in the field of medical imaging in VTK . I am quiet
> new to VTK . I have to render a volume (3d) and have to allow user to
> select points in 3d space, ie user can see the rendered volume and click
> anywhere and that point ( in near vicinity ) should be selected . I have to
> get the 3d coordinates of that particular point from the 2d display. The
> display can be rotated abt any axis so the selection is based on what is
> visible at any point of time in 2d. Can somebody tell me what all classes
> in VTK will be of help and where can I get a refrence manual for them. The
> documentation for VTK generated by DOxygen is quiet complex to understand ,
> is there any other doc available on the web.
>
>
> Regards
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