1. Method for detecting and tracking eye reference point positions of multiple observers, wherein the eye reference point positions are the positions of the pupils and/or the corners of the eyes, in image data of video frames, which are acquired by at least one image sensor, the method comprising: face finder instance for detecting face positions in video frames, said face finder instance extracting a much smaller sub-region from the total video frame as target face region for each face in order to transmit information of said target face region to at least one subsequent eye finder instance for detecting eye positions, said eye finder instance extracting a much smaller sub-region from each target face region as target eye region in order to transmit information of said target eye region to at least one subsequent eye tracker instance for tracking the eye positions, said eye tracker instance detecting the eye reference point positions in the target eye region in the current video frame and in the subsequent video frames and generating information for a tracking device, wherein each of the instances, or the face finder instance combined with one of the eye finder instance and the eye tracker instance, or a combination of the face finder instance and the eye finder instance and the eye tracker instance, are executed each in a dedicated computing unit proceeding in parallel with each other.