Panasonic AG-HMX100 3D Production Post White Paper - Page 9

Watching the Edges When composing films for smaller screens, filmmakers must take into account the prospect that objects with strong negative parallax (i.e. objects that intrude a significant distance into the viewer's space) may be truncated at the right or left sides of the screen, confusing the signals that viewers need in order to accurately place the objects in space. To correct this edge violation effect, movable mattes (or floating windows) may be applied in post, temporarily masking objects that reside too long at the sides of the frame. However, whenever possible, 3D filmmakers are well advised to compose their scenes so that objects with strong negative parallax are not allowed to linger for more than a second or two at the right and left sides of the frame. Minimizing Disparities To achieve effective 3D, every possible disparity between the images captured by the right and left lenses of the cameras must be minimized-with the obvious exception of the distint point-of-view of the two lenses. Accomplishing this goal requires maintaining precise synchronization between the cameras in addition to achieving a precise match between the optics of the lenses and a precise match between the imaging systems in the cameras. Mismatches in sync or in optics, as well as stray reflections, light flares, or stray objects in the frame-essentially any artifact introduced during production or post that affects one "eye" but not the other-can induce retinal rivalry-a conflict between the components of the stereo pair that disrupts the web of illusions that produce effective 3D. Filming Live Events When shooting live events such as stage performances and spectator sports, 3D filmmakers confront several limitations that can compromise their ability to capture effective 3D. Foremost among these are the need to make all of the decisions regarding I/O and convergence in real time plus the restriction upon the placement and motion of the cameras. The first limitation can be addressed by a stereographer who has access to 3D feeds from the cameras and can relay I/O and convergence decisions to camera assistants who can quickly adjust the I/O and convergence of the cameras. But since effective 3D places the viewer inside the action of the film, as an active participant and not merely as a passive spectator, the second limitation is more difficult to address. While live performances generally permit cameras to have a limited presence on the stage, spectator sports typically place strict limits on the space in which cameras can operate. Unfortunately, this space is outside the space of the key action in the game. Fig.8 - Live Event Spaces As a result of these limitations, 3D filmmakers who wish to effectively capture live events may need to depend upon the deployment of yet-to-be-invented robocams-remotecontrolled 3D cameras that can unobtrusively dip in and out of the subject space without interfering with the freedom of movement of the performers or the players and at the 9