[vtkusers] vtkImageImport Segfault

[Randall Hand]

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> 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
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