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Re: [photo-3d] Re: 3D X-ray CT


  • From: Ron Beck <rbeck@xxxxxxxx>
  • Subject: Re: [photo-3d] Re: 3D X-ray CT
  • Date: Fri, 27 Apr 2001 09:46:48 -0500

Anytime you have data that can provide x, y and z coordinates, you can create a 3D model. 
Viewing it on a 2D screen does not mean that the model is not 2D.  There are plenty of
programs that will take the x, y, and z information and generate a wire-frame or solid
model on the computer that you can then rotate to see every angle.  The ability to create
two different 2D pictures by offsetting the "camera" indicates that you truly have 3D
information.  This is not "so-called" 3D this is "actual" 3D.

"So-called" 3D are those graphics that are drawn in perspective but do not contain "z"
axis information and thus can't be rotated to a different angle.  You can't offset a
"camera" and get depth information because there is no depth information.

I've watched our CAD draftes draw items in 3D.  It took a lot longer, but once done, they
could display the object from any angle or even show slices of the object.  I even showed
him, with a lorngette viewer, how he could display the object from two camera angles and
view it in 3D.  He was quite impressed!

Some day I envision that doctors will be able to put on a pair of "glasses" that will
interact with the CT scanner and provide the two views to show the object in 3D floating
in front of them.  They already have "projection TV glasses.  How hard would it be to make
them with a left & right channel?

Ron

Michael Galazin wrote:
> 
> Abram Klooswyk wrote: "The computers have software to generate so-called 3D
> images
> from a consecutive series of such slices, but these 3D images
> are of the type you see everywhere as result of so-called 3D
> rendering CAD programs..."
> - - - -
> 
> Well, I agree with you in this, for the CT scans are definitely not stereo;
> but would just like to say that they are still "so-called 3D images" by your
> own admission, and so I called them "3D" with the hedges, "sort of, in
> slices."  See, I was covering my backside...  :)  But thanks for the more
> detailed explanation.  I for one did not know that they sometimes take such
> w-i-d-e slices (up to 10mm) for a single flat x-ray in the process of making
> up the series.
> 
> - - - -
> Abram also wrote: "Michael Galazin in his "big mistake" thread has made some
> other
> mistakes..."
> - - - -
> 
> Ah, sir, you have impugned my honor!  I challenge you to a duel with stereo
> cameras at twenty paces...  :)  [just kidding]
> 
> Best regards,
> 
> Mike Galazin
> 
> 
> 
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