DBW COMMUNICATION srl, based in Rome, since 2000 provides audiovisual and innovative services for filming and tv, aerial drones and HD OB-Vans including a 3D one.
This company is a founding member of the 3D STEREOSCOPIC GROUP consortium.
Stefano Rebecchi of DBW Communication describes some typical problems related to 3D.
"All the video materials video created for stereoscopic 3D viewing are subject to a very strict quality control.
The first correction is on the image: the two lenses are never completely identical and therefore produce differences in focus, and depth of field; this produces a vision out of phase between the two eyes, potentially causing serious eye problems, at times.
Other problems arise from the cameras that produce images slightly higher one from the other. A difference of only 1mm sometimes produces many discrepancies in the proportions from the height of the same subject in a long shot. It is the of vertical parallax issue: the brain couples these two images that do not coincide, creating problems.
Many other problems are related to language, for example, the "violation of the stereoscopic window."
In a 3D image the perimeter of the screen is a window through which we look at the scene.
The "stereographer" is the professional who determines the spatial positioning of objects: on the bottom of the screen or in the frontal plane, or they leave it and get closer to the viewer.
But sometimes, for example, in a medium shot of a man his face comes out of the natural boundary of the screen while the body remains inside unnaturally. The optical perspective paradox creates a scene beyond our normal understanding of people and objects.
A first control in a film is global as a whole by the stereographer.
If any doubt remains, an objective "stereoscopic processor" by Sony or 3ality comes into action.
However, there are cases where the violation of the stereoscopic window is intentional and justified because it is "author style".
When shooting in 3D on TV, as in sports, there are cuts which correspond to the positions of the many cameras on field, always double for each position. DBW Communication is able to manage simultaneously up to 26 HDTV cameras for filming in 3D-HD through the use of 13 stereoscopic motorized rigs. All functions of the Rigs, as well as those of the cameras, are controlled in real time by a series of C-Motion high precision motors.
The cameras are connected via fiber optics to the studio and equipped with high-precision motors that receive control information from the director.
Each camera has its own very expensive dedicated processor. A professional specialist - or "convergence puller" - controls the processor and performs the continuous corrections of convergence.
Sometimes, in sports, some 2DHD signals are converted in 3D and integrated with the rest of the production with a three frames delay.
The two factors that determine the 3D effect are the distance between the lenses - trying to repeat the distance between the eyes, and the point at which the eyes are crossed - which represents the convergence.
In a typical 3D football game shooting the feeling of depth is -sometimes- recreated so much higher than that the viewer sitting in the same position of cameras would have.
The lenses of the cameras are placed farthest away voluntarily on the rig at a distance greater than the actual between the pupils and in some cases even more than 70 cm. Thus the information between the two virtual eyes differ a lot and the 3D effect is much emphasized.”
