Reducing optical crosstalk in affordable systems of virtual environment

We have implemented a scheme for elimination of depolarization artefacts in passive stereo-projection systems. These problems appear due to non-perfectness of stereo-projection equipment: depolarization of the light due to reflection from the screen or due to the passage through the screen; non-ideality of polarizing filters; mixing of left- and right-eye images in a change of relative orientation of the filters. These effects lead to strong violations in stereo-perception (known as "ghosts"). They can be eliminated by software methods, using linear filtering of the image before its projection to the screen, based on the formula L\´ = L -αR, R\´ = R -αL , where L, R are images, destined for the left and right eye respectively, α is constant, defining intensity of the ghosts. This receipt, in theory leading to exact compensation of the ghosts, in practice possesses certain limitations, which allow not complete elimination but only strong suppression of the ghosts, at very careful calibration of the system. We have implemented this algorithm in VE system Avango by means of texture mappings. All necessary operations are performed by the graphics board, thus providing the real-time rendering rate. The described method considerably improves stability of stereo-perception, making high-quality performances of virtual environment possible on affordable equipment.