[vtkusers] vtkImageGradient.cxx changes, why??

[Asad A. Abu-Tarif]

I just forgot to paste the other changes that forced vtkImageGradient to
have
a VTK_FLOAT output, you know them :-)
Asad
       __________________________________________________
     /                        Asad A. Abu-Tarif
\
     |   Computer Engineering.
|
     |   PhD Candidate, Rensselaer Polytechnic Institute (RPI).       |
     |   tarifa at rpi.edu
|
     \___________________________________________________/

----- Original Message -----
From: "Asad A. Abu-Tarif" <tarifa at rpi.edu>
To: "vtk User List" <vtkusers at public.kitware.com>
Sent: Friday, December 07, 2001 12:01 AM
Subject: [vtkusers] vtkImageGradient.cxx changes, why??


> Hi,
> I sent an email earlier today asking about a code that I used to run fine
> on vtk3.12 and it started giving me trouble when I upgraded to vtk3.2.
> The code basically inputs a structured points data set with scalar
> type VTK_UNSIGNED_CHAR to vtkImageGradient, vtkImageGradientMagnitude
> and then to vtkImageNonMaximumSuppression.
> The problem I'm facing is that vtkImageNonMaximumSuppression
> complains about vtkImageGradient output being of scalar type
> VTK_UNSIGNED_CHAR while the output of vtkImageGradientMagnitude
> has a VTK_FLOAT scalar type.
> The changes below that caused this (in vtk3.2 and vtk4.0) in effect limit
> the use of those classes to data set types of VTK_FLOAT.
>
> The question is, is there a good reason why we can't find the gradient of
> a data set with VTK_UNSIGNED_CHAR scalars?? Why did you make the
> change?? I know it makes sense to have vtkImageGradient always output
> a VTK_FLOAT. However, if you do that, you shouldn't require that
> vtkImageGradientMagnitude
> and vtkImageNonMaximumSuppression have the scalar type of the input
> and the output the same!!
>
> The changes still exist in vtk4.0 and hence we still can't find the
gradient
> of a data set unless its scalars are of type VTK_FLOAT!!
>
> Regards,
> Asad
>
> ================Line 104===================================
> outData->SetScalarType(VTK_FLOAT);
> ================end-Line 104================================
>
> ==========Lines 258 to 264=======================================
> // this filter expects that input is the same type as output.
>   if (outData->GetScalarType() != VTK_FLOAT)
>     {
>     vtkErrorMacro(<< "Execute: output ScalarType, " <<
> outData->GetScalarType()
>                   << ", must be float\n");
>     return;
>     }
> ==========end-Lines 258 to 264=======================================
>
>
>
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