A method of estimating a size parameter of a virtual screen , the method comprising acquiring , from a physical camera , a plurality of captured images (510 - 530) that represent a reflector reflecting a virtual pattern displayed on a virtual screen and a physical pattern displayed on a physical plane, wherein each of the plurality of captured images is acquired by adjusting a reflection angle of the reflector; determining at least one first transformation parameter for each virtual camera from among a plurality of virtual cameras relative to a reference camera of the plurality of virtual cameras based on a rotation parameter R and a translation parameter t associated with intersections of the physical pattern in each captured image of the plurality of captured images, wherein each virtual camera from among the plurality of virtual cameras corresponds to the physical camera for a respective reflection angle of the reflector , wherein a size parameter of the physical pattern is known; determining at least one second transformation parameter for each respective one from among the plurality of virtual cameras relative to the reference camera based on a rotation parameter R and a translation parameter t associated with intersections of the virtual pattern in each captured image of the plurality of captured images; and estimating a size parameter of the virtual screen based on each of the at least one first transformation parameter and each of the at least one second transformation parameter, wherein the estimating the size parameter comprises estimating a value that corresponds to a minimum difference between a respective one from among the at least one first transformation parameter and a corresponding one from among the at least one second transformation parameter. acquiring , from a physical camera , a plurality of captured images (510 - 530) that represent a reflector reflecting a virtual pattern displayed on a virtual screen and a physical pattern displayed on a physical plane, wherein each of the plurality of captured images is acquired by adjusting a reflection angle of the reflector; determining at least one first transformation parameter for each virtual camera from among a plurality of virtual cameras relative to a reference camera of the plurality of virtual cameras based on a rotation parameter R and a translation parameter t associated with intersections of the physical pattern in each captured image of the plurality of captured images, wherein each virtual camera from among the plurality of virtual cameras corresponds to the physical camera for a respective reflection angle of the reflector , wherein a size parameter of the physical pattern is known; determining at least one second transformation parameter for each respective one from among the plurality of virtual cameras relative to the reference camera based on a rotation parameter R and a translation parameter t associated with intersections of the virtual pattern in each captured image of the plurality of captured images; and estimating a size parameter of the virtual screen based on each of the at least one first transformation parameter and each of the at least one second transformation parameter, wherein the estimating the size parameter comprises estimating a value that corresponds to a minimum difference between a respective one from among the at least one first transformation parameter and a corresponding one from among the at least one second transformation parameter. <EOS>