[vtkusers] how do I traverse the scalars of a vtkImageData?

[Nico Vermaas]

Mathieu,

I actually got a compiler error ("invalid initializer") with that statement, so I changed it to:

float* minmax=(float*)imagedata->GetScalarRange();

Then my minmax has these values:
minmax[0]: 2.30112e-07 
minmax[1]: 0.276428

(which are the correct values)

Nico

====================================================
Nico Vermaas
ASTRON - Westerbork Synthesis Radio Telescope
Schattenberg 1 - 9433 TA Zwiggelte - The Netherlands

tel: +31 593 598710                 
vermaas at astron.nl 
====================================================
>>> Mathieu Malaterre <Mathieu.Malaterre at creatis.insa-lyon.fr> 06/13/03 11:51 AM >>>
What is the result of:

float minmax[2] = imagedata->GetScalarRange();
std::cout << "scalar range:" << minmax[0] << "," << minmax[1] << '\n';

mathieu

Nico Vermaas wrote:
> Mathieu,
> 
> Thank you for pointing me in the right direction. I do not get the correct results yet (just a black cube like in Space Odyssee 2001, so the scalar data is not copied yet), but at least it is a step closer.
> 
> Nico 
> 
> ====================================================
> Nico Vermaas
> ASTRON - Westerbork Synthesis Radio Telescope
> Schattenberg 1 - 9433 TA Zwiggelte - The Netherlands
> 
> tel: +31 593 598710                 
> vermaas at astron.nl 
> ====================================================
> 
>>>>Mathieu Malaterre <Mathieu.Malaterre at creatis.insa-lyon.fr> 06/13/03 10:01 AM >>>
> 
> Nico,
> 
>  imagedata->Update(); //important
>  float minmax[2] = imagedata->GetScalarRange();
> 
>  vtkImageShiftScale::SetShift(-minmax[0]);
>  vtkImageShiftScale::SetScale(255./(minmax[1]-minmax[0]));
>  vtkImageShiftScale::SetOutputScalarTypeToUnsignedChar ()
> 
> See:
> http://www.vtk.org/doc/nightly/html/classvtkImageShiftScale.html
> 
> 
> HTH
> mathieu
> 
> Nico Vermaas wrote:
> 
>>Hi,
>>
>>To make volume rendering possible I want to convert the scalars in an vtkImageData to unsigned chars. I need to change them and make them range from 0 - 255.
>>  
>>I used to use SetScalar, but that doesn't seem to work any longer in VTK4. So what is the best way to traverse the scalar values in a vtkImageData? (getting, changing and setting the values?).
>>
>>Greetings,
>>
>>Nico
>>
>>
>>====================================================
>>Nico Vermaas
>>ASTRON - Westerbork Synthesis Radio Telescope
>>Schattenberg 1 - 9433 TA Zwiggelte - The Netherlands
>>
>>tel: +31 593 598710                 
>>vermaas at astron.nl 
>>====================================================
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> 
> 
> 


-- 
Mathieu Malaterre
CREATIS
28 Avenue du Doyen LEPINE
B.P. Lyon-Montchat
69394 Lyon Cedex 03
http://www.creatis.insa-lyon.fr/~malaterre/