# How to read a binary structured\_points data file from a fortran code in VTK?
**URL:** https://discourse.vtk.org/t/how-to-read-a-binary-structured-points-data-file-from-a-fortran-code-in-vtk/307
**Category:** Support
**Created:** [February 22, 2019, 3:53am UTC](https://discourse.vtk.org/t/how-to-read-a-binary-structured-points-data-file-from-a-fortran-code-in-vtk/307 "2019-02-22T03:53:47Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@singularity](https://discourse.vtk.org/u/singularity)
#### Post date: [February 22, 2019, 3:53am UTC](https://discourse.vtk.org/t/how-to-read-a-binary-structured-points-data-file-from-a-fortran-code-in-vtk/307/1 "2019-02-22T03:53:47Z")
I am new to VTK, and I am trying to read a binary structured\_points (image data) file in vtk but getting the “Error reading binary data” error with a blank window. I am using a simple fortran program to create the data file (gaussian field data) as follows,
```
program gaussian
implicit none
integer i, j, k
character(1) c
open(unit=100, file='energyDensity.vtk',
1 form="unformatted",access="stream")
write(100) '# vtk DataFile Version 3.0', new_line(c)
write(100) 'First time trying vtk import \n', new_line(c)
write(100) 'BINARY', new_line(c)
write(100) 'DATASET STRUCTURED_POINTS', new_line(c)
write(100) 'DIMENSIONS 101 101 101', new_line(c)
write(100) 'ORIGIN 0 0 0', new_line(c)
write(100) 'SPACING 1 1 1', new_line(c)
write(100) 'POINT_DATA 1030301', new_line(c)
write(100) 'SCALARS volume_scalars double 1', new_line(c)
write(100) 'LOOKUP_TABLE default', new_line(c)
do k = -50,50
do j = -50,50
do i = -50,50
write(100) 50.*exp(float((-(i*i+j*j+k*k))/25))
enddo
enddo
enddo
close(100)
endprogram
```
VTK reads and plots the data nicely if the data is in ASCII format (see the picture below)
I am using the following code C++ in VTK to read the data (without any setting for endian),
```
vtkNew reader;
reader->SetFileName (argv[1]);
reader->Update();
```
I have tried searching a lot on internet but couldn’t find the correct way of reading structured\_points data in binary. It seems there is no way of setting the endian thing for structured points reader as well. I am not sure what do here. Any help would be really appreciated.
---
### Author:  [@singularity](https://discourse.vtk.org/u/singularity)
#### Post date: [February 23, 2019, 6:56pm UTC](https://discourse.vtk.org/t/how-to-read-a-binary-structured-points-data-file-from-a-fortran-code-in-vtk/307/2 "2019-02-23T18:56:10Z")
It seems the VTK user guide is not very clear about legacy formats only accepting big\_endian byte ordering. The following changes to the code solved the problem for me.
```
program gaussian
implicit none
integer i, j, k
character(1) c
real(kind=8) x
open(unit=100, file='energyDensity.vtk',
1 form="unformatted",access="stream",convert="big_endian")
write(100) '# vtk DataFile Version 3.0', new_line(c)
write(100) 'First time trying vtk import \n', new_line(c)
write(100) 'BINARY', new_line(c)
write(100) 'DATASET STRUCTURED_POINTS', new_line(c)
write(100) 'DIMENSIONS 101 101 101', new_line(c)
write(100) 'ORIGIN 0 0 0', new_line(c)
write(100) 'SPACING 1 1 1', new_line(c)
write(100) 'POINT_DATA 1030301', new_line(c)
write(100) 'SCALARS volume_scalars double 1', new_line(c)
write(100) 'LOOKUP_TABLE default', new_line(c)
do k = -50,50
do j = -50,50
do i = -50,50
x=50.*exp(real((-(i*i+j*j+k*k))/25,8))
write(100) x
enddo
enddo
enddo
close(100)
endprogram
```
---
### Author:  [@lorensen](https://discourse.vtk.org/u/lorensen)
#### Post date: [February 23, 2019, 7:15pm UTC](https://discourse.vtk.org/t/how-to-read-a-binary-structured-points-data-file-from-a-fortran-code-in-vtk/307/3 "2019-02-23T19:15:14Z")
Here is a description of the legacy formats:
[https://lorensen.github.io/VTKExamples/site/VTKFileFormats/](https://lorensen.github.io/VTKExamples/site/VTKFileFormats/)