[Insight-users] CovariantVectorImageExtractComponent

[Luis Ibanez]

Hi Jesse,

The Z (third) component of a Vector is indexed as "2"
because we use the natural indexing order of C/C++.

So, if you want to extract:

        X component  -->  use index [0]
        Y component  -->  use index [1]
        Z component  -->  use index [2]

By asking for index "3" in the command line arguments of
the CovariantVectorImageExtractComponent program you are
probably going to provoke a segmentation fault.


We should actually add an if() in order to test if the
index is in the range [0:2].



   Regards,


      Luis


--------------
Jesse wrote:
> Hi,
>  
> Now I can get component X and Y, but can't get Z using 
> CovariantVectorImageExtractComponent VectorDeformationField .mhd 
> 11.mhd 22.mhd 3
>  
> header file
>  
> 
> ObjectType = Image
> 
> NDims = 3
> 
> BinaryData = True
> 
> BinaryDataByteOrderMSB = False
> 
> DimSize = 200 200 176
> 
> ElementNumberOfChannels = 3
> 
> ElementType = MET_FLOAT
> 
> ElementDataFile = 2.raw
> 
> 
> Bests
>  
> Jesse
> 
> */Luis Ibanez <luis.ibanez at kitware.com>/* wrote:
> 
> 
>     Hi Jesse,
> 
>     What is the actual pixel type of your input image
>     VectorDeformationField.mhd ?
> 
> 
>     Note that this example is reading the image as Float,
>     and then reducing it to unsigned short.
> 
> 
>     Please post to the list the content of the MetaImage
>     header file
> 
>     VectorDeformationField.mhd
> 
> 
>     That will help us to check if the image dimensions
>     in the header are what you expect.
> 
> 
>     Thanks
> 
> 
>     Luis
> 
> 
> 
>     --------------
>     Jesse wrote:
>      > Hi Luis,
>      >
>      > I got the new version and tested it.
>      >
>      > VectorDeformationField is about 81M , which include three
>      > component, That is, each component should contain 27M, In line 71, I
>      > modify it const unsigned int Dimension = 3; But after run
>      > CovariantVectorImageExtractComponent VectorDeformationField .mhd
>     11.mhd
>      > 22.m! hd 1, the reult image is all zero, in fact the component
>     wasn't
>      > zeros. in addition 11.mhd is 64K, 22.mhd 32k.
>      >
>      > Regards
>      >
>      > Jesse
>      > */Luis Ibanez /* wrote:
>      >
>      >
>      > Hi Jesse,
>      >
>      > Thanks for pointing this out.
>      >
>      > We just commited a fix for this file in to the CVS repository.
>      >
>      >
>     http://www.itk.org/cgi-bin/viewcvs.cgi/Examples/IO/CovariantVectorImageExtractComponent.cxx?root=Insight&r1=1.7&r2=1.8
>      >
>      > Please give it a try and let us know if you find any problem,
>      >
>      >
>      > Thanks
>      >
>      >
>      > Luis
>      >
>      >
>      >
>      > ---------------
>      > Jesse wrote:
>      >
>      > > Hi all
>      > >
>      > > I found a question in CovariantVectorImageExtractComponent.cxx,
>      > There
>      > > wasn't argv[2] in it. That is we can't get the non-normalized
>      > output.
>      > > Also, when i wa! nt to get the second component using ,
>      > >
>      > > CovariantVectorImageExtractComponent sr.mhd 11.mhd 22.mhd 2
>      > >
>      > > the reult image is all zero, infact the component wasn't zeros.
>      > >
>      > > Best
>      > >
>      > > Jesse
>      > >
>      > >
>      >
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