[vtkusers] Anybody out there???Help!!!

[David E. Jones]

Alvina D' Silva wrote:

> Hi all!
>       I did'nt receive any answers, so I thought I'd repost the questions
>
>      Please Help me !!!!
>
> 1.    I was trying out the examples  - "Medical*.cxx" which use contour filters .
>     These filters as well as marching cubes ask the value range ( 'SetValue' method). While values like
> 500(skin extraction) & 1150(bone extraction) work fine for the sample images, they do not hold good for all.
> Some of my MR images needed values of 30000 for bone extraction !
>
>     Is there no limited value range which will hold good for different sets of images? ( This is essential, since
> users will be asked to input this value ). Or is there any other way about this  (without specifying values ) ?
>
> 2. Given a set of Images(x-y), what classes do I use & how do I use them to obtain the other coordinate axes( viz x-z & y-z )?
>
> 3.   Is there any way I can increase the speed of execution (other than decimate)  ?  I'm on windows NT &
> am using VC++.
>
> 4. How do I close the openGL window without closing my main window ?
>
> 5. Does vtkImageReader support raw files? (tried to read some bin files but was unsuccessful)
>
> Would be grateful if someone could help ,
> Alvina
>

I'll take a shot at answering your questions.

 1)  In general, if the image data doesn't conform to any standard, you need to pick a value
       to segment your data.  This is frequently done using a histogram.  If two materials are
       represented by two peaks in the histogram, you can choose the value at the low point
       between the peaks as the contour value.  Much more sophisticated techniques can be
       used.  (If your data is supposed to conform to some medical standard,  I can't answer
       your question.)

  2)  You can use vtkImageReslice.

  3)   Be sure to use vtkStripper since most hardware processes "triangle strips" faster.
         Also,  using vtkProperty with BackfaceCullingOn may help since triangles that
          aren't visible won't be processed by the rendering hardware.

   4)  I don't understand this question.  I normally only have one window.

   5)  Yes.  e.g.

             vtkImageReader reader
                reader SetDataExtent 0 999 0 999 0 499
                reader SetDataVOI 100 769 100 869 0 499
                reader SetFilePrefix "0629001/0629001.rec"
                reader SetFilePattern "%s%4.4d.img"
                reader SetDataScalarType $VTK_SHORT

           If you are looking at data with your NT machine which was orginally made on a non-Intel
           (probably Unix) machine you'll need to also use

                reader SetDataByteOrderToBigEndian


Dave



--
David E Jones
Du Pont Central Research
Experimental Station, Bldg 320
Wilmington, DE 19880-0320


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