EduCam: Cinematic Vocabulary for Educational Videos

Cinematography relies on a rich vocabulary of shots and framing parameters to communicate narrative event structures. This cinematic vocabulary stems from the physical capabilities of camera movement and uses aesthetic aspects to engage the audience and influence audience comprehension. At present, automatic physical camera control is limited in cinematic vocabulary. Virtual cameras, on the other hand, are capable of executing a variety of cinematic idioms. Specifically, shot composition, match cut, and establishing shot sequence are three common cinematic techniques often lacking in automated physical camera systems. This paper proposes an architecture called EduCam as a platform for employing virtual camera control techniques in the limited stochastic physical environment of lecture capturing. EduCam uses reactive algorithms for real time camera coverage with hierarchical constraint satisfaction techniques for offline editing. Amateur video has become an important medium for disseminating educational content. The DIY community routinely creates instructional videos and tutorials while professional educators publish entire courses on Gooru and Coursera (Coursera 2014; Gooru 2014). Video gives educators the ability to flip the classroom, pushing passive viewing outside of the classroom and bringing interactivity and discussion back in. With video, educators have access to cinematic idioms to shape the narrative of their material. However these idioms rely on a high threshold of videography knowledge, equipment, and time. So educators use static cameras with time-consuming editing or automatic lecture capture systems. Current automatic lecture capture are passive capture systems, created to record the oratory style of the educator to his live audience rather than employ cinematic vocabulary. Moreover, their coverage typically consists of just a few cameras in the back of the classroom. However this reduces their shot vocabulary to long and medium shots with limited shot composition capability. Current virtual camera control algorithms are able to employ the full variety of shots and some cinematic transitions. However they do stochastic physical environment and typically assume unlimited camera coverage. Copyright c © 2014, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved. This paper focuses on three cinematic idioms that are common in professionally-shot educational videos and documentaries: shot composition, match cut, and the establishing shot sequence, It proposes EduCam, an architecture that allows for the employment of virtual camera control algorithms in the physical lecture capture environment. EduCam uses real time reactive camera coverage to allow for offline editing with hierarchal constrain satisfaction algorithms. This paper will evaluate the current physical automatic camera control for their cinematic capacity, discuss current virtual cinematography and finally outline how EduCam allows for hierarchal constraint satisfaction editing in a physical world. Figure 1: An example of good shot composition from Maltese Falcon. The subject is on the upper left third lines and his gaze is into the open space. (Bordwell 2014) Cinematic Vocabulary The three most common cinematic idioms used to engage audiences in content-driven film are shot composition, match cuts, and establishing shot sequence. Shot Composition ensures the shot is visually engaging and cues the audience to the subject of the shot. Generally a good engaging composition employs rule of thirds and is from an angle that emphasizes perspective. Subjects are typically on the side of the frame opposite of where they are moving or gazing (see Figure 1). Match Cuts are used to smoothly transition an audience’s eyes from one shot to another. In it the area of interest from the second shot is often matched with the area of interest in the first shot as shown in Figure 2. This maintains the audience’s eyes on the subject and prevents ”jitteriness” or loss Intelligent Cinematography and Editing: Papers from the AAAI-14 Workshop