In this line of research, we are creating interactive laser display systems that are capable of sensing interaction without the use of external cameras. These display systems use modulated galvo-scanning lasers to project laser light and then detect it with a fast photodetector. This enables highly responsive (up to 1000 Hz) detection of interaction with the projector graphics. Some potential uses for this work are implementing interactive spatial Augmented Reality interfaces and displays that present dynamic information on real-world surfaces and overlapping real and virtual environments to create seamless interfaces and displays where the use of existing headsets is not practical.
This research includes developing a “Laser Graphics Processing Unit” (LGPU) featuring a proposed re-configurable graphics pipeline capable of minimal latency interactive feedback, without the need of computer communication. This is a novel approach for creating interactive graphics where a simple program describes the interaction on a vertex. Similar in design to a geometry or fragment shader on a GPU, these programs are uploaded on initialisation and do not require input from any external micro-controller while running. The interaction shader takes input from a light sensor and updates the vertex and fragment shader, an operation that can be parallelised. Once loaded onto our prototype LGPU the pipeline can create laser graphics that react within 4 ms of interaction and can run without input from a computer. The pipeline achieves this low latency by having the interaction shader communicate with the geometry and vertex shaders that are also running on the LGPU. This enables the creation of low latency displays such as car counters, musical instrument interfaces, and non-touch projected widgets or buttons. From our testing we were able to achieve a reaction time of 4 ms and from a range of up to 15 m.
- Haebich, J., Sandor, C., Cassinelli, A., Interactive Minimal Latency Laser Graphics Pipeline. SA ‘20: ACM SIGGRAPH Asia 2020 Emerging Technologies, [12.2020]. PDF