A Moving Match.
Up and Away
Technocrane. Steadicam. The language of high end motion picture production is the language of the moving camera. To operate successfully in the pressure of a high end feature film shoot, a tracking system needs to be very fast, accurate, reliable, and non-intrusive.
Previzion, in conjunction with the Airtrack module and the Intersense IS-1200 VisTracker, provides a powerful general tracking solution. Use the high accuracy rotary data of the Airtrack combined with the 6DOF tracking capabilities of the Intersense for accurate Steadicam and running handheld shots.
For Technocrane work, placing the Intersense on the top mount of a Technocrane and the Airtrack on the underslung head provides a tracking method that is independent of the underlying mechanical hardware.
Starting with the Intersense’s position and orientation, Previzion can calculate the forward kinematics from the IS-1200 to the camera lens, using the offset measurements of the underslung remote head and the angular measurements of the Airtrack. (Available Q2 2009) Of course, if encoder data from the underslung head is available, this can be used instead.
The Right Lights
Many other tracking systems have active emitters that can cause reflections from shiny surfaces and cause visible artifacts on camera footage. Others, such as most motion capture type systems, require dozens of cameras, unobstructed volumes, and are prone to go out of calibration if bumped. Still others require tracking targets that interfere with the placement of lights.
The Intersense uses circular binary coded digital patterns as shown above in a ‘constellation’ pattern. The XYZ positions and orientations of each marker are surveyed and loaded. Once the Intersense camera can see 5 targets simultaneously, it can solve for its position and orientation.
The fiducial targets are a natural fit with Space Lights, which are frequently used on soundstages to provide a diffused overhead light. Printed on clear film and attached to the bottom of the light, they provide a safe, accurate positional reference. Since only a few targets are needed (about one every 15-20 feet on a typical stage), the overall lighting is unaffected.