Friendly vector field visualisation using VTK and Python.
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Chagu (pronounced châghu, or knife) is a Python module designed to ease visualisation of vector fields. It is designed to render magnetic moment vector fields from the discipline of micromagnetics, but can be extended to any project requiring vector field plots. It uses VTK to do this. Here is a pretty example:

Quiver plot

"Python eh? I bet it's really slow!"

As of 23/04/2016, the test suite creates 25 visualisations, and performs 204 (somewhat basic) render operations all in 6.37 seconds on my 2012 Dell, without compiled Python files. Not subtracting the time for other testing tasks,

thats at most 0.03 seconds per render operation.

That's pretty fast (though you should thank VTK for that).


To use Chagu like we do, you will need:

  • Python 2.7.10
  • VTK 5.10.1 or 6.3.0 (support for >=7 is coming, possibly)
  • Numpy
  • Matplotlib
  • GraphViz (the python module)

Getting Started and Helping Out

To get some idea of how to use this module, add the path of this repository to your PYTHONPATH. Some examples are in "example/" (obviously), which demonstrate the functionality of this module.

If you want to help out, check the issue tracker for tasks and create a fork or branch to implement the feature you want to create or bug you want to fix. Do also let me know if Chagu has been helpful in your work!

A Word on Offscreen Rendering

Some systems seem to have trouble rendering offscreen with VTK. This is important when trying to save a batch of images. One solution to this problem is to render using a virtual framebuffer, which can be done using Xvfb, Xpra, or similar. As an example in your terminal:

$ xpra start :25
$ export DISPLAY=:25
$ python
$ xpra stop :25

For more information on this, visit