Implementation of Green Screen/Chroma Key Technology During Online Lectures

Abstract

The COVID-19 pandemic has caused an almost universal shift towards remote learning in higher education institutions, where teaching is now commonly conducted via synchronous or asynchronous online lectures. Much of the pedagogical literature indicates that the options for teachers to demonstrate non-verbal immediacy in online lectures and courses are severely limited, significantly reducing the opportunity to enhance students’ motivation to learn. In this work, digital chroma key compositing (i.e. background removal) using a green screen and an open source software was adapted and implemented to livestream online lectures, where the lecturer’s webcam-captured image was digitally inserted in real time onto the lecture slides on the main screen. This allowed the lecturer’s non-verbal behaviours such as facial expressions, body posture, hand gestures, and eye contact to be obviously, immediately, and efficiently expressed. This enabled the lecturer to capture the students’ attention more easily, as well as maintain a high level of student engagement with the lecture content during remote learning. The chroma key compositing method was implemented in the course GEH1032 “Modern Technology in Medicine and Healthcare” at the National University of Singapore (NUS), where a basic studio was set up in an office space using equipment that is affordable and accessible to individual faculty members. Comments on the use of this technology from both the mid-term and the end-of-term student feedback exercises were highly favourable. A set of detailed, step-by-step instructions regarding the instrumentation and software setup is provided in the Appendix as part of the supporting materials.