shwirl 0.1.2

About shwirl

shwirl is a custom standalone Python program to visualise spectral data cubes with ray-tracing volume rendering. The program has been developed to investigate transfer functions and graphics shaders as enablers for scientific visualisation of astronomical data. Details about transfer functions and shaders developed and implemented in shwirl can be found in a full length article by Vohl, Fluke, Barnes & Hassan (Submitted).

A transfer function is an arbitrary function that combines volumetric elements (or voxels) to set the colour, intensity, or transparency level of each pixel in the final image. A graphics shader is an algorithmic kernel used to compute several properties of the final image such as colour, depth, and/or transparency. Shaders are particularly suited to computing transfer functions, and are an integral part of the graphics pipeline on Graphics Processing Units.

The program utilises [Astropy](http://www.astropy.org) to handle FITS files and World Coordinate System, [Qt](http://www.qtcentre.org) (and [PyQt](https://www.riverbankcomputing.com/software/pyqt/download5)) for the user interface, and [VisPy](http://vispy.org), an object-oriented Python visualisation library binding onto OpenGL. We implemented the algorithms in the fragment shader using the GLSL language.

The software has been tested on Linux, Mac, and Windows machines, including remote desktop on cloud computing infrastructure. While the software is available for download and ready to visualise data, this is not intended as a full software release just yet. The open source code allows interested individuals to inspect how custom shaders can be written, and can be a starting point to develop a more generic visualisation and analysis software.