Ice Crystal Halos

Lars Gislén’s streetlight halo simulator

Lars Gislén’s streetlight halo simulator

The halo application simulates streetlight halos ( 1 ). It can handle plate and column crystals as well as Parry oriented crystals. It can generate stereo pictures both for viewing in a stereo viewer or directly with “crossed yes”. The application can also generate a data file with the 3D location of the crystals involved in the display that can later be viewed in a separate 3D viewer.

There is a short PDF manual together with an explanation of how the halo is simulated. Finally you can download the (rather messy) Java source code.

Detailed (large recycle value) halos may take the order of one hour to simulate. With the least detailed (recycle = 1) setting it takes much shorter time.

There are two implementations of the halo applications, one for Macintosh OS X 10.4+ and one for Windows. A Windows machine may need to download the Java Runtime Environment (JRE) that is available free ( 2 )

Text: Lars Gislén


  • Another option is that Lars develops his software. The spatial viewer is very nice.

  • Yeah I hope it can work so you don’t have to download special Java software. I hope it will be like or similar to Halosim. It would be cool to do divergent light halos the same way you do halos with Halosim I think an all sky simulation in color with 256 levels for fine details will look sweet.

  • The simulation in the main window of the application is actually done with MILLIONS of colours. The sky is black, which is the normal colour of a night sky. However, the stereo pictures are plain black and white.
    I use Java because Java programs are platform independent and run equally well on Mac OSX, Windows, Linux, Unix… The Java Runtime Environment is free and can be downloaded and installed within minutes.


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