Camera Control in Computer Graphics

SIGRAPH ASIA 2009 Tutorial: Camera Control in Computer Graphics

Camera Control in Computer Graphics

Marc Christie (Université de Nantes, France)Patrick Olivier (Newcastle University, UK)

Introduction• hard to over emphasize the importance of

effective camera control (positioning & movement)

• central issue in a number of applications both current (e.g. visualization & games) and future (visual analytics & interactive story telling)

• relatively under-researched:• open issues in formulating requirements & evaluation

criteria• intrinsic complexity of basic geometric characterization

• clearly it is possible to create customized procedural controllers for cameras...


Tutorial goals1. review existing camera control schemes2.motivate through empirical evidence:

• application requirements• current practice (film and new media)

3.general camera control formulations4. representation & reasoning

requirements5.characterize camera control research

agenda


• applications & motivations for camera control

• camera control and cinematography• interactive control• automated approached• dealing with occlusion• closing remarks and open issues

Tutorial: structure


Smart graphics agenda

“synthesis of graphics utilizing an explicit model of the user, application & computational context”

• user: cognitive (perception, motor, memory & reasoning)...

• application: physical, functional, teleological, ...

• computational: processing, display, interaction devices, ...

• typically utilizes explicit models of one or more

• plenty of examples beyond camera control:• perceptual graphics, intelligent user interfaces

• requires representation & reasoning about graphics


Motivations: applications• exploring motivations and characteristics

• review application practice• review cinematographic practice

• relevant application domains:• modelers• games• visualization • multimodal systems

• camera control problem depends upon:• application domain• nature of the user• balance of interactive and automated control


Application: 3D modelers


Application: 3D modelers


Application: 3D modelers• 3D artists specify:

• camera position• look-at / up vectors

• control provided:• classical interpolation methods (splines with key

frames/control points)• fine control of the velocity curves supported• target constraints supported

• other basic notions from cinematic practice are not supported (e.g. framing)

• designer is the cameraman (not the director)


Multimodal systems• generation of coordinated natural language and

graphics• typically the problem is generating a camera set-up (for

an existing model) to support the linguistic references• existing (but unsatisfactory) solutions:

• predefined views (using “canned” references)• cutaways and transparency (overcome occlusion)• multiple viewports (overcome occlusion)

• full requirements (“co-generation” of language & graphics):

• linguistically felicitous graphical synthesis• sensitivity to viewer’s scene cognition• sensitivity to semantics of spatial language


Multimodal systems

• default views• transparencySeligmann & Feiner [SF91,SF93]

• multiple viewsBares & Lester [BL99]


Visualization• conceptually more straight forward• configurations:

• essentially spatial data (sci viz)• spatial metaphors for multidimensional data (data

viz)• spectrum of camera control support:

• full interactive control• constrained interaction• fully autonomous

• nature of constraints arises from:• the application (and task being supported)• underlying knowledge base


Visualization


Application: Games• require camera control

• during game play (real-time)

• between game play (cut scenes)

• available resources tightly constrained

• classes of viewpoint• first person

• third person

• bird’s eye

• cinematic

• key problems:• occlusion vs geometric complexity

• gameplay vs cinematic qualities

• visual consistency


Application: Games“Problems such as clunky controls and a frustrating camera, which were excusable in the early games, have steadily degraded the quality of the series releases over time.... Once you get the hang of it you can effortlessly overcome even the most imposing obstacles without difficulty. It's also always abundantly clear which ledges you can hang on or jump between, so the only challenge is positioning the camera so you can see where you're trying to go, which can be frustrating. In tight spots it can be difficult to get a good view of the ledge you need to jump to, and sometimes it's easy to misjudge a jump if you don't have the camera aligned just right. The camera problems are intermittent though, and most of the time you have a fairly good view of the surroundings.”http://shopper.cnet.com/Tomb_Raider_Legend_PC/4512-9696_9-31568589.html


Games and the movies...


Documents

Camera Control in Computer Graphics