Serial Position Interface (SPI)
“The Heart of Shotoku VR Tracking”
The Shotoku Serial Position Interface, or SPI, is at the heart of Shotoku’s VR Tracking. Monitoring the data from the encoders and sensors mounted on our manual and robotic VR products, the SPI uses proprietary algorithms to determine the absolute position of the camera’s optical center. The resultant data, using industry-standard protocols, is sent out to the graphics system synchronized to video reference. Using highly accurate rotation measurements on each wheel, every joint, and even the camera lens’ zoom and focus, the SPI is able to locate the pedestal or crane relative to the origin point anywhere in the studio. These measurements also generate pedestal rotation data which is added to the head pan angle to provide true pan angle information.
The Shotoku SPI uses data from the high-precision encoders attached directly to the moving parts of the head, lens or crane, to detect and update precisely the exact location of every axis and communicate this in a high-speed serial data stream to the VR graphics system. The powerful processing electronics at the core of the SPI ensure that data is produced accurately and fast enough to be synchronized with every frame of video, ensuring smooth movement of the real and virtual worlds.
For PTZF systems the SPI only needs to move through the centre points of pan and tilt, and reach the end-points of zoom and focus to be completely referenced – making the process extremely quick and simple. For systems including VR pedestals where a reference point in 3-dimensional space is required, there is a simple reference procedure using a floor tile in the corner of the studio. The addition of our patented SPi-TOUCH makes this process even simpler by eliminating the need for a reference tile and simply carrying out a 2-point triangulation procedure.
Pictured: Serial Position Interface (TO-25A) and Power Supply Unit (TO-26)