Error writing binary VTK files

问题

I am trying to write a basic binary VTK file to display some data using ParaView but I have some errors and I don't understand why. Here is my test code in C++:

#include <iostream>
#include <fstream>

double myarray[72] = {
0,0,0,1,0,0,2,0,0,3,0,0,4,0,0,
5,0,0,0,1,0,1,1,0,2,1,0,3,1,0,
4,1,0,5,1,0,0,2,0,1,2,0,2,2,0,
3,2,0,4,2,0,5,2,0,0,3,0,1,3,0,
2,3,0,3,3,0,4,3,0,5,3,0};
int main()
{
    std::ofstream vtkstream("test01.vtk", std::ios::out | std::ios::trunc);
    bool ascii = false;
    if (vtkstream) {
        vtkstream<<"# vtk DataFile Version 2.0"<<"\n";
        vtkstream<<"Exemple"<<"\n";
        if (ascii) {
            vtkstream<<"ASCII"<<"\n";
            vtkstream.close();
            vtkstream.clear();
            vtkstream.open("test01.vtk", std::ios::out | std::ios::app);
            vtkstream<<"DATASET STRUCTURED_GRID"<<std::endl;
            vtkstream<<"DIMENSIONS 6 4 1"<<std::endl;
            vtkstream<<"POINTS 24 double"<<std::endl;
            for (unsigned int i = 0; i < 72; ++i) {
                vtkstream<<myarray[i]<<" ";
            }
        } else {
            vtkstream<<"BINARY"<<"\n";
            vtkstream.close();
            vtkstream.clear();
            vtkstream.open("test01.vtk", std::ios::out | std::ios::app | std::ios::binary);
            vtkstream<<"DATASET STRUCTURED_GRID"<<std::endl;
            vtkstream<<"DIMENSIONS 6 4 1"<<std::endl;
            vtkstream<<"POINTS 24 double"<<std::endl;
            for (unsigned int i = 0; i < 72; ++i) {
                vtkstream<<myarray[i];
            }
        }
        vtkstream.close();
    } else {
        std::cout<<"ERROR"<<std::endl;
    }
    return 0;
}

The ASCII file format works perfectly but the binary version produces the following error in ParaView:

Generic Warning: In ........\src\VTK\IO\vtkDataReader.cxx, line 1363 Error reading binary data!

Where is my mistake in the VTK format?

回答1:

It seems that VTK assumes that binary files are written as big endian, whereas most PCs use little endian storage (see the bottom of page 2 of the VTK file formats document). Can you try swapping the byte order when writing binary data and see if this solves your problem?

See also this VTK users post, which is similar to this question.

回答2:

My 50 cents. Here is the code that finally worked for me. Using byte swap, and using the function write to skip the formatting of the << operator

#include <iostream>
#include <fstream>

// Thanks to https://stackoverflow.com/questions/105252
template <typename T>
void SwapEnd(T& var)
{
  char* varArray = reinterpret_cast<char*>(&var);
  for(long i = 0; i < static_cast<long>(sizeof(var)/2); i++)
    std::swap(varArray[sizeof(var) - 1 - i],varArray[i]);
}

double myarray[72] = {
  0.001,0.002,0,1,0,0,2,0,0,3,0,0,4,0,0,
  5,0,0,0,1,0,1,1,0,2,1,0,3,1,0,
  4,1,0,5,1,0,0,2,0,1,2,0,2,2,0,
  3,2,0,4,2,0,5,2,0,0,3,0,1,3,0,
  2,3,0,3,3,0,4,3,0,5,3,0};

int main()
{
  std::ofstream vtkstream;
  vtkstream.open("test.vtk", std::ios::out | std::ios::app | std::ios::binary);
  if (vtkstream) {
    vtkstream<<"# vtk DataFile Version 2.0"<<"\n";
    vtkstream<<"Exemple"<<"\n";
    vtkstream<<"BINARY"<<"\n";
    vtkstream<<"DATASET STRUCTURED_GRID"<<std::endl;
    vtkstream<<"DIMENSIONS 6 4 1"<<std::endl;
    vtkstream<<"POINTS 24 double"<<std::endl;
    for (unsigned int i = 0; i < 72; ++i) {
      SwapEnd(myarray[i]);
      vtkstream.write((char*)&myarray[i], sizeof(double));
    }
    vtkstream.close();
  } else {
    std::cout<<"ERROR"<<std::endl;
  }
  return 0;
}

来源：https://stackoverflow.com/questions/10913666/error-writing-binary-vtk-files

标签

c++

binaryfiles

vtk

paraview