A method for a head-mounted display device comprising a camera and an optical see through display worn by a user, the method being carried out by one or more processors and the method comprising: (S201) displaying, with the display, a marker image (IMG) that is capable of being perceived to be at least partially aligned with a real marker (MK1); (S212) detecting the real marker from an image captured with the camera; (S530) determining whether the user's head is in a substantially static condition, (S575) collecting, from the image or another image captured with the camera, calibration data that is to be used in setting at least one parameter for allowing an AR object displayed with the display to be perceived to correspond to an object in the scene, in response (S515) to an instruction given by the user, in the case where the user's head is determined to be in the substantially static condition, and setting the at least one parameter, wherein detecting the real marker includes deriving a temporal position and pose of the real marker based at least on the image, said temporal position and pose comprising an approximate position and pose of the detected real marker as transformed from a camera coordinate system into a display coordinate system using a default spatial relationship, and collecting the calibration data includes accepting the instruction in the case where a difference between the temporal position and pose and a predetermined position and pose is below a threshold, wherein, in a case where after the instruction is accepted, the user's head is first determined to be out of the substantially static condition and then to be in the substantially static condition, the calibration data is collected from an image captured with the camera in the case where the user's head is in the substantially static condition, and wherein displaying the marker image includes displaying a specific image with the display in the case where the difference is below the threshold. (S201) displaying, with the display, a marker image (IMG) that is capable of being perceived to be at least partially aligned with a real marker (MK1); (S212) detecting the real marker from an image captured with the camera; (S530) determining whether the user's head is in a substantially static condition, (S575) collecting, from the image or another image captured with the camera, calibration data that is to be used in setting at least one parameter for allowing an AR object displayed with the display to be perceived to correspond to an object in the scene, in response (S515) to an instruction given by the user, in the case where the user's head is determined to be in the substantially static condition, and setting the at least one parameter, wherein detecting the real marker includes deriving a temporal position and pose of the real marker based at least on the image, said temporal position and pose comprising an approximate position and pose of the detected real marker as transformed from a camera coordinate system into a display coordinate system using a default spatial relationship, and collecting the calibration data includes accepting the instruction in the case where a difference between the temporal position and pose and a predetermined position and pose is below a threshold, wherein, in a case where after the instruction is accepted, the user's head is first determined to be out of the substantially static condition and then to be in the substantially static condition, the calibration data is collected from an image captured with the camera in the case where the user's head is in the substantially static condition, and wherein displaying the marker image includes displaying a specific image with the display in the case where the difference is below the threshold. <EOS>