[vtkusers] vtkImageImport Segfault

[Mathieu Malaterre]

Randall,

	Hum I believe you can read those bytes but never use it... Could you 
try to read 3,840,384,800 bytes + 4 but set properly the dimension. If 
you are lucky enough no test is done to check consistency of datasize 
and dimension of data.

My 2 cents,
Mathieu

Randall Hand wrote:
> Well, I have an addition 4 bytes at the end of the file to skip as 
> well.. I suppose I could postprocess & write a new file without these 
> final 4 bytes, but that's gonna be pretty wasteful of disk space.  Is 
> there a way to skip them?
> 
> 
> 
> On 5/27/05, *Mathieu Malaterre* <mathieu.malaterre at kitware.com 
> <mailto:mathieu.malaterre at kitware.com>> wrote:
> 
>     Randall,
> 
>             Could you instead give vtkImageReader a try. Just specify
>     the lenght of
>     data you want to read: 3,840,384,800 bytes. By default vtkImageReader
>     start reading from the end. Thefore you are garantee to skip a
>     header if
>     any (4 bytes in your case apparently).
> 
>     HTH
>     Mathieu
> 
>     Randall Hand wrote:
>      > I'm attempting to load a simple "Brick of Bytes (BoB)" format
>     file into
>      > VTK.  It is 2191x2191x800 unsigned chars (3,840,384,800 bytes).
>     With 4
>      > bytes at the beginning that I have to skip (Gotta love fortran).  My
>      > code is like the following:
>      >
>      >     if (stat(argv[1], &file_info) == -1) {
>      >         perror("Unable to stat file!\n\t");
>      >         return -1;
>      >     }
>      >     fptr = fopen(argv[1], "r");
>      >     if ((data = (char*)malloc(file_info.st_size)) == NULL) {
>      >         perror("Unable to allocate memory!\n\t");
>      >         return -1;
>      >     }
>      >     dataptr = data;
>      >     fread(dataptr, 1, 4, fptr);
>      >     dataptr += 4;
>      >     printf("\n\n");
>      >     for(int i=0; i<xdim; i++) {
>      >         fread(dataptr, ydim,zdim,  fptr);
>      >         dataptr += (ydim * zdim);
>      >     }
>      >
>      >     vtkImageImport *import = vtkImageImport::New();
>      >     import->AddObserver(vtkCommand::ProgressEvent, progress);
>      >     import->SetDataScalarTypeToUnsignedChar();
>      >     import->SetNumberOfScalarComponents(1);
>      >     import->SetWholeExtent(1, xdim-1,
>      >                            1, ydim-1,
>      >                            1, zdim-1);
>      >     import->SetDataExtentToWholeExtent();
>      >     import->SetImportVoidPointer(data + skip);
>      >
>      >     vtkDataSetWriter *writer = vtkDataSetWriter::New();
>      >     writer->SetInput(import->GetOutput());
>      >     writer->SetFileName("resulting.vtk");
>      >     writer->Write();
>      >
>      >
>      > When I run this, however, the output VTK file only contains the
>     following:
>      > # vtk DataFile Version 3.0
>      > vtk output
>      > ASCII
>      > DATASET STRUCTURED_POINTS
>      > DIMENSIONS 2191 2191 800
>      > SPACING 1 1 1
>      > ORIGIN 1 1 1
>      >
>      > No data is actually written to the file.  When I try to connect
>     this to
>      > a rendering pipeline or start querying the resulting vtkDataSet for
>      > properties (Scalar ranges, number of points, etc) I get strange
>     results
>      > and eventually I get Segfault/Core dumps.  Often times the number of
>      > points listed comes out as a large negative number, instead of the
>      > 3.8bil that it should be.
>      >
>      > A stack trace of the core dumps only reveals this:
>      >
>      > [8:50:48am]% dbx imageimport
>      > dbx version 7.3.4 (86441_Nov11 MR) Nov 11 2002 11:31:55
>      > Core from signal SIGSEGV: Segmentation violation
>      > (dbx) where
>      >
>      > Thread 0x10000
>      >  >  0 vtkDataArrayTemplate<unsigned
>     char>::ComputeScalarRange(int)(this
>      > = 0xf4eb83c0, comp = 0)
>      >
>     ["/viz/home/rhand/src/ezViz/Utilities/VTK/Common/vtkDataArrayTemplate.txx":644,
>      > 0x85f2758]
>      > (dbx)
>      > (dbx) quit
>      >
>      >
>      >
>      > --
>      > Randall Hand
>      > http://www.yeraze.com
>      >
>      >
>      >
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> 
> 
> 
> -- 
> Randall Hand
> http://www.yeraze.com <http://www.yeraze.com>