My last column was about POV projects, which basically involve a linear array of LEDs that are spun in a circle, or otherwise move in a repeating motion. They blink as they move, and persistence of vision fills in the gaps so that the single line of LEDs can appear to create text or simple graphics.
When I see POV, however, I think first of POV-Ray, the Persistence of Vision Raytracer. This is an open source graphics project that has been around for a really long time. It generates 3D rendered images using the technique of ray tracing. Ray tracing works by defining in 3D space a scene or model, a virtual planar screen, and a viewpoint. Imaginary rays are cast from the viewpoint through each pixel of the virtual screen into the scene, and the pixel is colored according to which object in the scene it intersects. If the objects have reflectivity (or transparency) then the ray continues to be traced until it no longer reflects. This close modeling of physical reality is why ray tracing generates such realistic images that include reflections, blur, specular highlights, etc.
I took some graphics courses back in the day, and remember being fascinated by the technique of ray tracing. I wrote a simple ray tracer as a project. The scene was the obligatory mirrored ball over a checkered floor. I also participated in a group project that developed a renderer that combined ray tracing and radiosity. I tried to experiment with POV-Ray back then but as I recall my little 386SX computer was not up to the task of generating images in any kind of reasonable time.
I haven’t done any computer graphics in a long time, but writing last week’s column made me think of POV-Ray, so I looked it up. It’s still being developed, with the most recent release being 3.6.2. The POV-Ray site includes a Hall of Fame, with some stunning images that users have generated. Some of them are shown to the right.
Until I took this more recent look, I always thought the POV in POV-Ray stood for Point of View, which I think makes a lot more sense that Persistence of Vision. POV-Ray is available for Windows, Mac, and Linux. If you’ve got time, a multi-core processor, and lots of RAM, download it and give it a try.
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