A computer-implemented method of operating a visual data delivery system , the method comprising: processing a sequence of 3-dimensional, 3D, images of a body to generate first 2-dimensional, 2D, image data representing a first sequence of 2D images of the body, wherein the 2D images are images of the body in a 2D image plane through the 3D images, and wherein an amount of data representing the first 2D image data is less than an amount of data representing the 3D images from which the first 2D image data is generated; sending the first 2D image data to a display system for display of the first sequence of 2D images of the body by the display system ; processing the sequence of 3D images to generate one or more 3D models representing the body or a part of the body from the sequence of 3D images, and send the one or more 3D models to the display system ; or identify a type of body or type of body part shown in the sequence of 3D images, and send an indication of the identified type of body or type of body part, or an indication of one or more predetermined 3D models corresponding to the identified type of body or type of body part, to the display system ; receiving a 2D image plane adjustment indication from the display system , wherein the 2D image plane adjustment indication indicates a required rotation and/or translation of the 2D image plane; processing the sequence of 3D images and/or a further sequence of 3D images to generate second 2D image data representing a second sequence of 2D images of the body, wherein the 2D images in the second sequence of 2D images are images of the body in the rotated and/or translated 2D image plane; and sending the second 2D image data to the display system for display of the second sequence of 2D images of the body by the display system . processing a sequence of 3-dimensional, 3D, images of a body to generate first 2-dimensional, 2D, image data representing a first sequence of 2D images of the body, wherein the 2D images are images of the body in a 2D image plane through the 3D images, and wherein an amount of data representing the first 2D image data is less than an amount of data representing the 3D images from which the first 2D image data is generated; sending the first 2D image data to a display system for display of the first sequence of 2D images of the body by the display system ; processing the sequence of 3D images to generate one or more 3D models representing the body or a part of the body from the sequence of 3D images, and send the one or more 3D models to the display system ; or identify a type of body or type of body part shown in the sequence of 3D images, and send an indication of the identified type of body or type of body part, or an indication of one or more predetermined 3D models corresponding to the identified type of body or type of body part, to the display system ; generate one or more 3D models representing the body or a part of the body from the sequence of 3D images, and send the one or more 3D models to the display system ; or identify a type of body or type of body part shown in the sequence of 3D images, and send an indication of the identified type of body or type of body part, or an indication of one or more predetermined 3D models corresponding to the identified type of body or type of body part, to the display system ; receiving a 2D image plane adjustment indication from the display system , wherein the 2D image plane adjustment indication indicates a required rotation and/or translation of the 2D image plane; processing the sequence of 3D images and/or a further sequence of 3D images to generate second 2D image data representing a second sequence of 2D images of the body, wherein the 2D images in the second sequence of 2D images are images of the body in the rotated and/or translated 2D image plane; and sending the second 2D image data to the display system for display of the second sequence of 2D images of the body by the display system . <EOS>