Output visuailzation result to Paraview in binary

VTK/Paraview provides a document for users to write visualization result in Paraview readable file format. However, it lacks examples to show how to output the visualization result in binary with the code. To output data in binary format is more tricky than in ASCII format. This repository tries to use as simple as possible cases to show how to do this.

This repository supports rectilinear, structured and unstructured grid in both legacy format and XML format. In XML format, both serial and parallel implementations are supported. The sketch below shows the examples of structured and unstructured grids used in this repository. Three implementations are (a) a 2D arch, (b) a 3D arch and (c) a 3D arch in parallel. The grid generator can be found in the folder grid. All the examples are in the root path. The scripts to write data in legacy and XML formats are in the folder writeParaview.

First of all, add the path of BinaryParaview to PYTHONPATH:

PYTHONPATH=path/to/BinaryParaview:$PYTHONPATH

To run serial examples, just simply execute following commands in Terminal in Mac/Linux or cmd in Windows in the folder examples:

python Legacy_***.py

or/and

python Serial_XML_***.py

or just click run in IDE.

To run parallel examples, you should have mpi4py installed and then execute the following commands:

mpiexec -n 3 python Parallel_XML_***.py

which uses 3 processors to execute the python code. Yes, I used an ODD number.

• struct.pack is used to write binary data. For example, struct.pack("fff", *[1,2,3]) and struct.pack("iii", *[1,2,3]) pack data into 3 single-precision float and integer numbers respectively.
• Legacy format only supports writing data in big endian order. To write in big endian order, a > should be added in front of format characters. For example, struct.pack(">fff", *[1,2,3]) packs data in big endian order.
• In XML format, only appended is used in this repository. The appended data section begins with the first character after the underscore _ inside the AppendedData element. Data array has a format [#bytes][DATA], where [#bytes] is an integer value to specify the number of bytes in the block of data following it.