Advantages of a dedicated »STEREO-tracing« mode

Why using a built-in stereoscopic camera?

As you probably will know, it is very easy to create steroscopic views with POV-ray. Simply render the scene two times while applying a small lateral shift to the camera position. Using this approach, we will encounter three problems:

  1. The time amount needed will be doubled. With increasing quality demands, doing more sophisticated texturing and modelling, applying more advanced lighting techniques, you will soon arrive at rendering times of some hours up to some days anyway. So often we have to do a tradeoff. Very bad, as stereoscopy per se is much more quality demanding then "normal" flat imaging.
  2. Any random features used in the raytracing process will show up as image errors in stereoscopic view (similar to the problems encountered in animations). This is especially true for textures with "crand", area ligths with jitter or when using media.
  3. Generally, you can't use special camera types.

Such problems are solved or ameliorated by the patch presented here, as the STEREO- tracing is built into the core raytracing engine. The use of StereoCache datastructures allows the two half images to share computations. This already in simple scenes decreases the time amount needed to create a stereoscopic pair. And in scenes with some area lights and texturing, typical values range 150% (to be compared to 200% time amount for calculating two independent views with camera shift). The speed gain is especially noticable when using radiosity. In some cases, the stereo version needed only 115% of the mono version's rendering time. Complex ray object intersection calculations on the contrary, or the tracing of reflected and refracted rays and of media is not speeded up.

StereoCache solves the problems wiht crand and area lights. Jitter appears to be grainyness on the surface of the objects. On the other hand, media calculations have to be done twice independently for the two viewing rays in order to gain the impression of media floating in the air between the visible objects. Here the jitter problem remains.

As STEREO-tracing is built into the raytracer, it is posible to adjust the geometry of the camera projection indepently for every pixel in the image. This allows for camera constructions not to be achieved with real mechanic/optical cameras.

Why I wrote this patch

The primary reason is, that I need it for my own work.
As the main application for me is to create slides for projection, it has to work precisely with respect of the stereoscopic window. And I especially need fisheye type perspective.

This means you can be sure that there will be further developement. The patch now has been adapted to POV-Ray 3.5 and additional stereoscopic camera parameters were added, as a response to user feedback. A version based on POV-Ray 3.6 under developement. And moreover I am considering some additions to the texturing possibilities.

StereoPOV by Ichthyostega Hermann Vosseler home images usage download