[vtkusers] point picking problem.

[Peter Spring]

Dear all,

point picking is a old issue. i went thru some post on this mailing
list. and i got inspired indeed. yet i still have some problem
regarding point picking, please forgive my nescience.


the things i want to do is picking up some point in a medical iso
surface, display is generated from CT DICOM data.

following code display the point position on command line

vtkRenderWindowInteractor iren
    iren SetPicker picker
vtkCellPicker picker
    picker AddObserver EndPickEvent cbDisplayPoint
proc cbDisplayPoint {} {
    puts "You picked point: [picker GetPickPosition]"
}

however i also want to put an actual point on the surface, so what
shall i do in this case?  do i need use vtk point widget (maybe some
example code)?

and also,
i hope some one can explain to me a bit about the difference between
cell picker and point picker.


thank you very much

yours

Peter