[vtkusers] How to generate X-Ray Projection

[paulus joo]

Hi lisa,

Thank you for your kind information. But I am still not get it. Would you mind to inform me more detail how to implement a ray cast function that models x-ray attenuation (absorption and scattering) as you suggested?

I also tried to make a copy of vtkVolumeRayCastMIPFunction (.h and cxx), name it into vtkVolumeRayCastXRayFunction and modify the code inside which calculate the maksimum into calculate the average value. It works but the "X-Ray" image  is too soft (blurred). So, maybe your suggestion (x-ray attenuation) will give a better result.

Last, if you don't mind, would you inform me the way how I can save the projection (at 6 planes of the cube) of the result into image files?

Regards




----- Original Message ----- 
  From: Lisa Avila 
  To: paulus joo ; vtkusers at vtk.org 
  Sent: Sunday, June 27, 2004 8:46 PM
  Subject: Re: [vtkusers] How to generate X-Ray Projection


  Hello,



    1. I want to generate X-Ray 2D image from the 3D volume. Some articles on the internet mention that MIP projection can produce image look likes X-Ray image, and some articles mention about "average intensity projection" should be used to obtain X-Ray image. Which one (or both) was wrong?

  A MIP projection is a "maximum intensity projection" - the maximum value encountered along the ray (either raw scalar or opacity mapping) is used for resulting pixel value in the image. Therefore it is not like an x-ray in which (usually) the whole volume contributes to the final image. Average would be closer to an x-ray but remember this is just a rough approximation. You could also write a ray cast function that models x-ray attenuation (absorption and scattering) but keep in mind that the ray cast mapper only cast primary rays so you couldn't account for any second-order scattering effecfts.

  Lisa



------------------------------------------------------------------------------


  _______________________________________________
  This is the private VTK discussion list. 
  Please keep messages on-topic. Check the FAQ at: <http://public.kitware.com/cgi-bin/vtkfaq>
  Follow this link to subscribe/unsubscribe:
  http://www.vtk.org/mailman/listinfo/vtkusers
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.vtk.org/pipermail/vtkusers/attachments/20040629/be3e712c/attachment.htm>