Darshak - An Intelligent Cinematic Camera Planning System

A virtual camera is a powerful communicative tool in virtual environments. It is a window through which a viewer perceives the virtual world. For virtual environments with an underlying narrative component, there is a need for automated camera planning systems that account for the situational parameters of the interaction and not just the graphical arrangement of the virtual world. I propose a camera planning system called Darshak that takes as input a story in the form of sequence of events and generates a sequence of camera actions based on cinematic idioms. The camera actions, when executed in the virtual environment update a list of geometric constraints on the camera. A constraint solver then places the camera based on these constraints. Introduction and Related Work A 3D narrative-based system (e.g. video games and training simulations) must not only create engaging storyworld plans, it must use its media resources to tell the story effectively. In the work that I describe here, I will focus on one aspect of the effective creation of cinematic discourse: automatically determining the content and organization of a sequence of camera shots that film the action unfolding within a story world. Strategies for determining shot content in 3D virtual environments fall into one of three categories. Several research systems use camera constraints that are pre-specified relative to the subjects being viewed (Bares & Lester 1997). These approaches are of limited value in dynamic domains where constraints need to be dynamically generated. Other approaches, like many commercial computer games, provide dynamic camera positioning based on the viewpoint of the user’s character. However, these approaches limit the information about that story world that is conveyed to the user to just those elements of it that the user chooses to view. I propose a technique that falls along a third line of research – that of the automatic determination of shot composition based on the dynamics of the scene and the Copyright © 2006, American Association for Artificial Intelligence (www.aaai.org). All rights reserved. story events occurring within it. The ability of my narrative system to generate camera control directives automatically and dynamically is important for two reasons. First, automatic generation of camera shots can ensure that those objects in the environment that should be visible in shots are not obscured by scene geometry. Second, and more central to the current discussion, automatic composition of shots allows the system to select shot sequences that exploit cinematic knowledge relating shots to the unfolding action in order to more effectively communicate aspects of the plot. Cinematographers have identified patterns of shot sequences that define stereotypes for ways to film certain types of action or action sequences (Arijon 1976). These stereotypes are called film idioms; their use is central to the creation of a cinematic experience for a virtual world’s user.