Christoph Flüeler, system and software engineer, SRF
SLS is a lighting automation system, based on object tracking, that provides lighting optimized for broadcast/video purposes dynamically and in real time. Depending on the position of the camera and target people, lighting tasks (typically what are known as the highlight, the guide light and the fill light) are distributed among the available light sources (moving lights) so that the targets are optimally illuminated.
Building a new studio for news and sports, the aim was to achieve a very high degree of automation and thus a reduction in required staff. Nevertheless, with special news programmes and roundtable discussions with studio guests, unplanned movements cannot be excluded. Such scenarios, however, would require lighting staff, which could not have been arranged at short notice, especially for breaking news.
The lead of the SRF lighting team therefore suggested a proof-of-concept for a self- propelled lighting system that would enable professional lighting in the broadcast area without staff supervision. The basic idea was to track all people and objects (cameras) relevant for lighting and to calculate optimal lighting based on their position.
Different scenarios
At the moment, three possible scenarios are available:
- One person, one camera: the lighting follows the camera- target axis, and the axis is shifted when the target or the camera (or both) moves. Light direction, angle, focus and intensity is dynamically adjusted. If there are multiple cameras, the axis is switched according to the camera that is currently on air. The lighting director defines for each target person individually how they are to be illuminated, deciding with which intensity, from which directions (related to the camera axis), and with which focus an object/person is to be illuminated.
- Several people: if the people are separated by some distance, they are detected as individual lighting targets; if they are in groups, parameters can be set for large-area lighting.
- ‘Fences’ with presets: any area of the studio space can be configured for a specific behaviour of the lighting. Thus, a presenter at the desk can call up a preset individually optimized for hair and skin colour as well as body size. When they move outside this area, the lighting is switched to follower control; when they walk into the fence with guests, the lighting is extended and when they move towards the big screen, the lighting is optimized in relation to the camera axis.
We are dealing with a paradigm shift here: the classic lighting approach is reversed. It is not the lighting director who decides which light should shine where (programming presets), but the position of the target dictates with which lamps an optimal result is achieved in relation to the camera.
As the trackers are individual, a specific set of situations can be configured for each person according to hair or skin colour, size or gender.
From the very beginning, one of the declared aims of SLS was not to replace experienced lighting staff, but to improve/upgrade the lighting in situations where, for operational or financial reasons, no lighting staff can be arranged. The entire development was supported and driven by the lighting team at SRF – a good example of interdisciplinary cooperation.
This project was a runner-up in the EBU Technology & Innovation Award 2023. This article first appeared in issue 57 of EBU tech-i magazine.