We propose theoretical consideration and computer modeling of information pit recording and etching processes in chalcogenide vitreous semiconductors. We demonstrate how to record and develop information pits with the necessary shape and sizes in chalcogenide photoresists using gaussian laser beam and selective etching. It has been shown that phototransformed region cross-section could be almost trapezoidal or parabolic depending on the photoresist material optical absorption, recording beam power, exposure, etchant selectivity and etching time. Namely, during the laser illumination and thermal heating caused by it, photosensitive material is the quasi-equilibrium microscopic mixture of the transformed and non-transformed phases with different optical absorption coefficients: temperature dependent near the absorption edge "transformed" coefficient e α and almost independent coefficient . If after thermal heating, the photo-transformed region "bleaches" and the pit depth increases more rapidly under the following laser power increasing. If , the photo-transformed region "darkens" and the pit depth increases sub-linearly or even saturates under the following laser power increasing. Thus, almost parabolic or flattened pits appear in the case , whereas the pits with elongated tops appear in the case . After illumination, the spatial distribution of photo-transformed material fraction was calculated