[vtkusers] imagedata appearing upside down (sometimes..?)

Mon Mar 22 19:16:07 EST 2004

Hi,
Thanks again for your response

Okay actually I am creating the data and inputting it into the array
So from what I understand the values at row 0 of my array would appear at 
the bottom, and the values at row 100 lets say would appear towards the top

So I use subscript math to assign the values in my array as follows:
array [ row*TotalColumns + col ] = value;

and then do SetVoidArray as mentioned below..

So I'm alawys creating teh data the same way,  so why would it sometimes 
appear upside down and sometimes not..?  :s
Thanks again for your help!

Howard

>From: Mathieu Malaterre <mathieu.malaterre at kitware.com>
>To: Howard Katz <lost_bits1110 at hotmail.com>
>CC: vtkusers at vtk.org
>Subject: Re: [vtkusers] imagedata appearing upside down (sometimes..?)
>Date: Mon, 22 Mar 2004 19:10:38 -0500
>
>Howard,
>
>	Ok that's what I wanted ! Where does your data comes from ? Did you know 
>that VTK read the image data upside down ? Have a look at any image reader 
>like png, jpeg, tiff. You'll see that we read starting from the bottom. So 
>make sure your array is read starting from the bottom.
>
>	Or more generally use an already existing reader.
>
>HTH,
>Mathieu
>
>Howard Katz wrote:
>>Also,
>>just note that I input data using:
>>
>>VelocityVsTimeSampleFloatArray->SetVoidArray(array,TotalTimePoints*TotalCycles*NumBins, 
>>1 );
>>
>>where array is a 1D float array whcih represents a 2D array through 
>>subscirpt arithemtic by doing:
>>
>>array [ row*TotalColumns + col ] = value;
>>
>>Thanks..!
>>Howard
>>
>>>From: "Howard Katz" <lost_bits1110 at hotmail.com>
>>>To: mathieu.malaterre at kitware.com
>>>CC: vtkusers at vtk.org
>>>Subject: Re: [vtkusers] imagedata appearing upside down (sometimes..?)
>>>Date: Mon, 22 Mar 2004 23:11:20 +0000
>>>
>>>Hi,
>>>
>>>I called GetSpacing and it returns (1,1,1) just as I had specified..
>>>And I know the input values are correct i.e they're not negative or 
>>>anything because I also outputted this..
>>>And I noticed that whenever I don't add a camera to my renderer, nothing 
>>>happens when I change the spacing, is this normal?
>>>Okay below is some C++ code,
>>>So again its werid because the whole thing appears upside down only for 
>>>some cases and not others..?
>>>Anyways here it is:
>>>
>>>VelocityVsTimeSampleFloatArray->SetNumberOfComponents(1);
>>>VelocityVsTimeSampleFloatArray->SetNumberOfTuples(TotalCycles*NumVelocityBins*TotalTimePoints 
>>>);
>>>VelocityVsTimeSampleImageData->SetOrigin(-30, -85, 0);
>>>     
>>>VelocityVsTimeSampleImageData->GetPointData()->SetScalars(VelocityVsTimeSampleFloatArray);
>>>
>>>VelocityVsTimeSampleImageData->SetDimensions(TotalCycles*TotalTimePoints,NumVelocityBins, 
>>>1);
>>>VelocityVsTimeSampleImageData->SetScalarType(VTK_FLOAT);
>>>VelocityVsTimeSampleImageData->SetSpacing(1, 1, 1);
>>>
>>>ImageCast->SetInput( VelocityVsTimeSampleImageData);
>>>ImageCast->SetOutputScalarTypeToUnsignedChar();
>>>
>>>ImageMapToColors->SetInput(ImageCast->GetOutput());
>>>ImageMapToColors->SetLookupTable(SpectLUT);
>>>
>>>SpectActor->SetInput(ImageMapToColors->GetOutput());
>>>SpectActor->SetDisplayExtent( 0, TotalCycles*TotalTimePoints-1, 0, 
>>>NumVelocityBins-1, 0, 0 );
>>>
>>>Cam->SetPosition(0, 0, 325);
>>>Cam->SetFocalPoint(0,0,0);
>>>
>>>Ren1->SetBackground(0.3, 0.3, 0.3);
>>>Ren1->SetActiveCamera(Cam);
>>>Ren1->AddActor( SpectActor );
>>>
>>>RenWin->AddRenderer( Ren1 );
>>>RenWin->SetSize( 500, 500 );
>>>RenWin->SetInteractor(Iren);
>>>Iren->SetStillUpdateRate(1000);
>>>Iren->SetDesiredUpdateRate(1000);
>>>Iren->Initialize();
>>>Iren->Render();
>>>
>>>
>>>
>>>
>>>>From: Mathieu Malaterre <mathieu.malaterre at kitware.com>
>>>>To: Howard Katz <lost_bits1110 at hotmail.com>
>>>>CC: vtkusers at vtk.org
>>>>Subject: Re: [vtkusers] imagedata appearing upside down (sometimes..?)
>>>>Date: Mon, 22 Mar 2004 17:34:30 -0500
>>>>
>>>>Howard,
>>>>
>>>>     What does :
>>>>
>>>>//Call Update() before
>>>>print imagedata.GetSpacing()
>>>>
>>>>return ?
>>>>Could you reproduce the bad behavior using a tests from VTK ? Or could 
>>>>you send us a python/c++/tcl code that shows this problem.
>>>>
>>>>Thanks
>>>>Mathieu
>>>>
>>>>Howard Katz wrote:
>>>>
>>>>>Hi..
>>>>>What do you mean my spacing 'can' be negative...?
>>>>>:S
>>>>>Thanks again..!
>>>>>
>>>>>
>>>>>
>>>>>>From: Mathieu Malaterre <mathieu.malaterre at kitware.com>
>>>>>>To: Howard Katz <lost_bits1110 at hotmail.com>
>>>>>>CC: vtkusers at vtk.org
>>>>>>Subject: Re: [vtkusers] imagedata appearing upside down (sometimes..?)
>>>>>>Date: Mon, 22 Mar 2004 13:13:18 -0500
>>>>>>
>>>>>>Howard Katz wrote:
>>>>>>
>>>>>>>Hi,
>>>>>>>so has anyone run into the problem where their vtkImageData looks 
>>>>>>>upside down only sometiems depending on the input values..?  i.e. I 
>>>>>>>know I am inputting values 10, 20, 15 (for example) but these appear 
>>>>>>>at rows -10, -20, -15  (..and this will happen for the entire image 
>>>>>>>data)
>>>>>>>
>>>>>>>Can anyoen guess what my problem might be?
>>>>>>
>>>>>>
>>>>>>
>>>>>>You spacing can be negative, this happens typically in medical image 
>>>>>>data such a MINC or DICOM
>>>>>>
>>>>>>HTH
>>>>>>Mathieu
>>>>>>
>>>>>>
>>>>>
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>>>>
>>>>
>>>>
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