A method comprising: while a viewer is viewing a first stereoscopic image comprising a first left image and a first right image, rendered on one or more image displays and projected from the one or more image displays to a first virtual object plane at a first virtual object depth determined based at least in part on (i) a first left vergence angle of a left eye of the viewer and (ii) a first right vergence angle of a right eye of the viewer as the depth at which the left optical axis of the left eye and the right optical axis of the right eye coincide at a first virtual spatial location having the viewer's focus, determining a second left vergence angle of the left eye of the viewer and a second right vergence angle of the right eye of the viewer; determining, based at least in part on (i) the second left vergence angle of the left eye of the viewer and (ii) the second right vergence angle of the right eye of the viewer, a second virtual object depth as the depth at which the left optical axis of the left eye and the right optical axis of the right eye coincide at a second virtual spatial location having the viewer's focus; rendering a second stereoscopic image comprising a second left image and a second right image for the viewer on the one or more image displays, wherein the second stereoscopic image is subsequent to the first stereoscopic image; and projecting the second stereoscopic image from the one or more image displays to a second virtual object plane at the second virtual object depth, wherein the first and second left images and the first and second right images are generated from first and second input left images each representing a left eye view of a 3D image and first and second input right images each representing a right eye view of a 3D image, by applying one or more blurring filtering operations that blur one or more spatial regions of the first and second left images and the first and second right images relative to the first and second input left images and the first and second input right images, wherein the one or more spatial regions of the first left image and the first right image are away from the first virtual spatial location, wherein the one or more spatial regions of the second left image and the second right image are away from the second virtual spatial location, and wherein the blurring filter operations include a strength of blurring, the strength of blurring increasing as the distance of an image detail in the first and second left and right images represented at the first and second virtual object planes increases relative to the first and second virtual spatial locations. while a viewer is viewing a first stereoscopic image comprising a first left image and a first right image, rendered on one or more image displays and projected from the one or more image displays to a first virtual object plane at a first virtual object depth determined based at least in part on (i) a first left vergence angle of a left eye of the viewer and (ii) a first right vergence angle of a right eye of the viewer as the depth at which the left optical axis of the left eye and the right optical axis of the right eye coincide at a first virtual spatial location having the viewer's focus, determining a second left vergence angle of the left eye of the viewer and a second right vergence angle of the right eye of the viewer; determining, based at least in part on (i) the second left vergence angle of the left eye of the viewer and (ii) the second right vergence angle of the right eye of the viewer, a second virtual object depth as the depth at which the left optical axis of the left eye and the right optical axis of the right eye coincide at a second virtual spatial location having the viewer's focus; rendering a second stereoscopic image comprising a second left image and a second right image for the viewer on the one or more image displays, wherein the second stereoscopic image is subsequent to the first stereoscopic image; and projecting the second stereoscopic image from the one or more image displays to a second virtual object plane at the second virtual object depth,