Abstract: There is provided mechanisms for determining calibration of positions of EEG electrodes on a subject. A method is performed by a controller. The method comprises obtaining a set of signals representative of estimated positions for the EEG electrodes when placed on the subject. Each of the estimated positions represents a position of one of the EEG electrodes relative to the subject. The method comprises comparing the set of signals representative of estimated positions to a set of reference signals representative of reference positions. The set of reference positions represents intended positions for the EEG electrodes when placed on the subject. The method comprises determining the calibration of positions of the EEG electrodes using a difference between a property of the obtained signals and the set of reference signals.

Abstract: A method for controlling projection of an image in an extended reality device is disclosed. The extended reality device comprising an optical element, a display, and a motion tracker, wherein the optical element and/or the display are mounted movement flexible in the extended reality device. The method comprises obtaining motion information of the extended reality device from the motion tracker; determining a compensating movement of the optical element and/or the display for projection of the image based on the obtained motion information of the extended reality device; and controlling projection of the image by moving the optical element and/or the display based on the determined compensating movement. Corresponding computer program product, apparatus, and extended reality headset are also disclosed.

Abstract: A method for controlling movement of a virtual character in a virtual reality environment provided by a virtual reality device is disclosed. The virtual reality device comprising a motion tracker, wherein positions of the virtual character in the virtual reality environment correlate to positions of a user of the virtual reality device in a physical movement area. The method comprises obtaining positions of the virtual reality device in the physical movement area from the motion tracker, determining positions of the virtual character in the virtual reality environment based on the obtained positions of the virtual reality device in the physical movement area, and controlling movement of the virtual character in the virtual reality environment by applying the determined positions in a movement of the virtual character in relation to a position C in the physical movement area. Corresponding computer program product, apparatus, and virtual reality headset are also disclosed.