1. Method for real-time rendering and generating of computer-generated video holograms from three-dimensional image data with depth information, for a holographic display device (HDD), which comprises light modulator means (SLM), and which reconstructs mainly that wave front that would be emitted by an object towards observer eyes, where the position and viewing direction of an observer defines a view of the scene (3D-S) and where the observer is assigned with at least one virtual observer window (OW), which is situated in an observer plane near the observer eyes, and where in a preparatory process step the scene coordinates are transformed and scene illumination calculations are carried out considering the viewing direction of the observer, comprising the following process steps: Step (1): 3D rendering and generation of the depth map of scene section data between two parallel section planes, which are disposed at right angles to the viewing direction of the observer, Step (2): transformation of the scene section data, i.e. calculation of the propagation of the light waves to the observer window, Step (3): repetition of the steps of 3D rendering and transforming, while successively displacing the section planes in the viewing direction, until the entire scene is transformed, and addition of the results of the individual transformations, Step (4): back-transformation, where the aggregated data are transformed from the observer plane into a hologram plane which coincides with the position of a light modulator means (SLM), and which is situated at a final distance and parallel to the observer plane, so to generate hologram data for the video hologram, Step (5): encoding, where after a normalisation step the pixel values are calculated and transferred in a frame buffer in order to reconstruct the three-dimensional scene, where the individual process steps are executed on a graphics sub-system by one or multiple graphics processors.