Ray Tracing

Ray Tracing in the WinGX Package

The WinGX package offers two possibilities for producing presentation and publication quality ray-traced illustrations of molecular and crystal packing diagrams, using either the Raster3D package or POV-Ray.

The steps required to produce a Raster3D illustration are as follows :
1. Select the required view and content of the illustration using Ortep3 for Windows. This may correspond to a molecular view or a cell-packing diagram. The current colour scheme and orientation are saved by selecting the menu item Save Raster3D File. The saved file is called RASTER3D.DAT.
2. This file is then interpreted by the Raster3D programs, and may be illustrated as
  - thermal ellipsoids (RASTEP)
  - Van der Waals surfaces (VdWSpheres) or
  - rods or balls and sticks (RODS)
  Selecting either of these programs displays a menu which allows customisation of the illustration. The file RASTER.R3D is then written, which is the scene description file for the illustration.
3. This scene description file may then be rendered using the program RENDER, which outputs a TIFF format file call RASTER3D.TIF.
4. This TIFF file may be viewed by standard graphics packages such as PaintShopPro or Adobe PhotoShop.
5. In the 32-bit version of WinGX, steps 3 and 4 are now carried out automatically after step 2, assuming a GraphicsViewer has been specified in setup.
6. Alternatively, the ORTEP implementation in PLATON now also supports RASTER3D output. Select the required view and then click on the Raster3D button. A file RASTER3D.R3D will be written, and if the environment variable R3DEXE has been set to the fullpath of render.exe (usually c:\wingx\for_prog\render.exe) then this program will be invoked automatically to render the scene description file. View the resultant TIFF file with menu item View TIF File.
POV-Ray files corresponding to current views can be output by the programs ORTEP-3 for Windows, PLUTON or STRUPLO using the requisite menu item. These are rendered by the excellent FREE ray-tracing program POV-Ray which is obtainable from http://www.povray.org/. The graphical output can be in a variety of formats (BMP, PNG, TARGA).

The scene-description language of POV-Ray is highly complex and very flexible and the files produced by the WinGX programs contain only the basic components of the scene-description. Users wishing to add more artistic features to these illustrations will need to consult the POV-Ray documentation. The current version of POV-Ray for Windows (at the time of writing version 3.1g) contains full online documentation. The complete POV-Ray manual in several different electronic forms is also available from this site.

Another program which can produce POV-Ray output for crystallographic scenes is DRAWxtl available from http://homestead.juno.com/larry.finger/files/