To enable stereo tracking, connect a compatible stereo rig to the RS232 port on Previzion marked Encoders/Stereo. (COM port 4) If streaming metadata is detected, a green light will go on by the stereo tracker. Stereo rigs must be set to communicate at 38400.
Present rigs supported are:
- Element Technica 3D – With special firm ware from 3alitytechnica
- Cameron/Pace Group
Rig vs. Actual IO/Convergence
The IO and convergence metadata that is generated by a 3D rig are usually based on the distances between the rig’s front pivot points. The pivot points on a stereoscopic rig are mechanical junctions that are frequently not aligned with the entry pupil (nodal point) locations of the lenses used. In the case of zoom lenses, the entry pupils move when zoomed in or out, so the pivot points cannot align for more than one specific focal length, thus requiring correction.
The effect of the moving entry pupil locations becomes larger as the rig is operated in a more converged fashion.
Previzion compensates for the moving entry pupil locations using its calibrated lens data, obtained through the lens calibration procedure outlined in a later chapter. Previzion uses this data, along with measurements from the rig pivots to the sensor location on the rig, in order to calculate the true IO and convergence data that the rig and lens combination is actually set to.
To achieve this accuracy, the distance from the rig pivot point to the camera sensor plane must be measured and entered into Previzion. Click the Configure button next to the stereo tracker in question to bring up the configuration panel.
The front rig pivots are almost always ahead of the camera sensor plane, so this value is usually positive.
In the Element Technica 3D and CPG rigs, the front pivot is the pivot point that the stereo metadata is based upon.