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 :
- 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.
- 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.
- This scene description file may then be rendered using the program RENDER,
which outputs a TIFF format file call RASTER3D.TIF.
- This TIFF file may be viewed by standard graphics packages such as PaintShopPro or Adobe PhotoShop.
- 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.
- 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/