Naostage’s K SYSTEM Flow tracking system uses two cameras and a 3D venue model to track performers across the hillside stage at Freilichtbühne Hallenberg, an outdoor theatre in Germany. Deployed for the venue’s production of Das Wunder von Bern, the system calculates performers’ height automatically, allowing operators to follow their movements in two dimensions while the software handles the third axis.
The system uses two Naostage KAM cameras – one mounted at the front edge of the stage roof for a top-down view of the central playing area, and another positioned in the audience to capture the stage from the front. It sends PSN tracking data over the network to a grandMA3 onPC system, where two tracking markers can be assigned to moving lights. The rig includes Chauvet Professional and Claypaky fixtures, and the system does not control the fixtures directly.
K SYSTEM Flow’s Auto Z function calculates a performer’s height in real time from the venue’s 3D model. Operators manually follow performers along the X and Y axes using a two-dimensional screen. The arrangement allows any suitable moving light to act as a followspot, without permanently dedicating fixtures to that role. Installation was completed in one working day, followed by calibration and fixture alignment.
The venue’s terrain presented a particular challenge, with an elevation change of 15m across a stage measuring approximately 40m wide by 25m deep. The sloping ground also made calibration difficult because it offered few reliable level reference points. Naostage developed a free calibration mode during commissioning to accommodate the site.
Valentin Eppner, technical director at Freilichtbühne Hallenberg, said: “For the operators, not having to control the Z-axis manually makes a significant difference. Especially on our stage, with a big elevation difference, having the height calculated automatically allows the operator to concentrate entirely on following the performer across the 2D surface instead of having to manage three axes at the same time.”
The volunteer-run theatre staged 16 performances of Das Wunder von Bern during summer 2026, with around 70 performers. Previously, its team relied on a conventional followspot from a single fixed position, limiting coverage across the wide stage. The new system also allows moving lights to contribute gobos, colour and beam effects to the followspot design. Feedback from the installation informed further development, including tracking with a Z-offset and a dedicated 2D mode. The system was supplied through So-light, Naostage’s distributor.
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