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3D Graphics and Railroading

Persistence Of Vision Ray Tracing - POVRAY

povray is a high performance 3D image rendering program. It was developed on Unix and has been ported to other OS environments. It is supported via the web site: www.povray.org A closely related site is the International Ray Tracing Competition. Many of the images found at ITRC were rendered using povray.

Scenes to be rendered by povray are described by using its scene description language which is documented in an extensive manual. Objects are described using a combination of geometric shapes. Light sources are specified as well as the camera position. There are sample scenes of varying complexity installed with the software that may be used as examples when you construct your own scene.

A sample scene generated using povray:

JPEG image - low quality - 320x240
PNG image - low quality - 320x240
Click here to see a JPEG - high quality 800x600 pixel view. (file size: 59KB) Click here to see a PNG - high quality 800x600 pixel view. (file size: 457KB)
Notice the difference in image quality between the JPEG and the PNG 800x600 pixel images. The fuzziness is most obvious on the front and side of the cab in the JPEG image. It is due to the way the image is compressed. PNG uses a different method which works better for areas of roughly constant color.

The scene description file: 040.pov

Commands to use to render this scene;

  • render a single large frame - low quality
    povray   -i 040.pov +d +p +w800 +h600
  • render a single large frame - high quality
    povray   -i 040.pov +d +p +w800 +h600 +q9 +a0.1 +am2
  • render 20 small, low quality frames and view the animated scene
    povray  -i 040.pov +kff20 +fp +kc
    animate -delay 10 040*ppm
Some day I'd like to add steam and smoke to the image. Also other objects in the background would be nice. It is not obvious in these pictures but there is a piston that moves inside of the cylinders in the animation.

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