The camera station section of the Visibility on Photos pane has two controls.
The first is the Point Coverage control which sets whether the point coverage boundary is shown on photos. A camera that has been calibrated in version 6 or later stores the extents of the calibration coverage as a ‘rectangle’ in each photo frame. A calibration can only ‘solve’ for the parts of the lens that contain 3D points, so the lens is essentially uncalibrated outside of this ‘frame’. Viewing the point coverage boundary provides an indication of whether points are marked within the calibrated region of the lens.
The 3D checkbox allows you to view projected 3D camera stations in photos (i.e. only oriented camera stations for photos that were taken at angles that are visible from the current photo). This helps visualize camera angle differences in photos.
Note: 3D items are displayed on oriented photographs only. See the section on Photo Projections for more information.