[vtkusers] Problem with allocating memory for huge vtkImage and memory-fragmentation ?

[Ashika Umanga Umagiliya]

Thanks Dženan,

I am using MinGW and QT Opensource , so I am restricted to 32Bit.
Before using vtkImageData , I used simple data-structure that allocates one
memory block for each Z-Slice,(not a continuous block for the entire volume
).That helped me to avoid the memory fragmentation.
Now I moved to vtkImagaData.Does it always allocate one
large continuous block or is there any flag to change memory allocation
scheme?

Thanks

2011/4/8 Dženan Zukić <dzenanz at gmail.com>

> If you are close to the limit of the address space (like using 1GB block on
> 32bit machine), it is a problem. However on 64bit system 4GB block is not an
> issue.
>
> Regards,
> Dženan
>
> On Fri, Apr 8, 2011 at 07:42, Ashika Umanga Umagiliya <
> aumanga at biggjapan.com> wrote:
>
>> Greetings all,
>>
>> In our application we need to load large volumedata (2000x2000x1000  - 8
>> bpp).
>> In the "Vtk Users Guide" I came across following  example to create
>> vtkImageData.
>>
>> vtkImageData *id=vtkImageData::New();
>> id->SetDimentions(nx,ny,nz);
>> id->SetScalarTypeToUnsignedChar();
>> id->SetNumberOfScalarComponents(1);
>> id->AllocateScalars();
>>
>> //Fill in scalar values
>> unsigned char *ptr=(unsigned char*)id->GetScalarPointer();
>> for(int i=0;i<nx*ny*nx;i++){
>>  *ptr++=i;
>> }
>>
>> Looking at the way assigning values and the method GetScalarPointer(); ,
>> it seems that one block of memory is allocated for entire (nx*ny*nz) pixels.
>> If it allocate entire memory block,would it cause problem with
>> memory-fragmentation ?
>> Or is there any other memory allocation schema ?
>>
>> Thanks in advance.
>>
>>
>>
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