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Narrative-Driven Camera Control for Cinematic Replay of Computer Games
Quentin Galvane
Rémi Ronfard
Marc Christie
Nicolas Szilas
Motivation 2
How to produce a fully automatic cinematic replay ?
Use of cinematic in video games is more and more popular
Necessity for Cinematic Replay of game sessions
A lot is made manually
Control multiple dynamic cameras
Create complementary, informative and well composed shots
3
Edit them to produce a cinematic replay
Motivation
Virtual cinematographer
4
[He et al. 1996] [Christianson et al. 1996]
Related work
[Jhala 2006]
Behavior Trees
[Markowitz et al. 2011]
DCCL
[Christianson et al. 1996]
Darshak
Idiom-based solutions
Require the definition of idioms Setting the cameras
Selecting the appropriate moments
Do not handle all the situations No solution if the idiom doesn’t exist
5
Real-time Cinematography
[Lino et al. 2010]
Afterthought
[Dominguez et al. 2011]
Related work
Action-based solutions
Film editing
[Lino et al. 2011]
Steering cameras
[Galvane et al. 2013]
Character-based solutions
6
Hitchcock principle:
Measure characters’ importance
Use characters’ importance to
Control the cameras with steering behaviors
Perform the editing
Key Idea
The size of a character on the screen should be proportional to its narrative importance in the story.
7 Overview
Cinematic replay Edit the camera rushes
Camera shots Animate the cameras
Camera specifications Retrieve the spec from the behaviors
Camera Behaviors
Target configuration Extract targets
Narrative importance Compute characters’ narrative importance
Game Record the Scenario and Animations
8
Cinematic replay Edit the camera rushes
Camera shots Animate the cameras
Camera specifications Retrieve the spec from the behaviors
Camera Behaviors
Target configuration Extract targets
Narrative importance Compute characters’ narrative importance
Game Record the Scenario and Animations
Narrative importance
How to compute characters’ importance?
9 Narrative importance
Classical two-level narrative structure: Beats that describe a narrative unit
[Mateas and Stern 2002] Atomic actions that compose a beat
Actions
Beats
Scenario Game
Dialog
A speaks to B
B speaks to A
Fight
A moves to B
A kicks B B punches A
…
… …
10 Narrative importance
B: Action Importance
A: Action importance
B: Beat Importance
A: Beat importance
Actions
Beats
Scenario Game
Dialog
A speaks to B
B speaks to A
Fight
A moves to B
A kicks B B punches A
…
… …
11 Narrative importance
Computing Characters’ importance:
Significance of a character in an action Sc
Relevance of an action R
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Cinematic replay Edit the camera rushes
Camera shots Animate the cameras
Camera specifications Retrieve the spec from the behaviors
Camera Behaviors
Target configuration Extract targets
Narrative importance Compute characters’ narrative importance
Game Record the Scenario and Animations
Target configuration
13 Target configuration
3 Types of targets
PC: Player Character
Pi: Primary non-player characters
Si: Secondary non-player characters
Defined using threshold on importance
At each frame
14 Camera Behaviors
Cinematic replay Edit the camera rushes
Camera shots Animate the cameras
Camera specifications Retrieve the spec from the behaviors
Camera Behaviors
Target configuration Extract targets
Narrative importance Compute characters’ narrative importance
Game Record the Scenario and Animations
15 Camera Behaviors
Definition of camera behaviors:
Example of camera behavior: First person camera
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CU on Frank 3/4backright screen left in foreground and Lili
screen center
MS on Frank screen center and Lily 3/4backleft screen
right in foreground
POV Frank MCU on Lili screencenter
POV Lili CU on Frank screencenter
Camera Behaviors
17 Camera shots
Cinematic replay Edit the camera rushes
Camera shots Animate the cameras
Camera specifications Retrieve the spec from the behaviors
Camera Behaviors
Target configuration Extract targets
Narrative importance Compute characters’ narrative importance
Game Record the Scenario and Animations
From PSL specification to camera placement Pruning Process :
18
For the <size> constraint
For the <profile> constraint
For the <angle> constraint
For the <back|fore> ground constraint
Camera shots - Placement
From PSL specification to camera placement Pruning Process :
19 Camera shots - Placement
<angle> constraint <size> constraint <profile> constraint
MS on P1 screen left and P2 ¾ left screen right
Use of steering cameras to:
Maintain shot specifications
Perform smooth transitions between them
Two main forces implemented:
Containing force
Positioning force
20 Camera shots - Motion
Positioning force Ensure the framing and screen composition
Composed of two distinct forces F1 and F2
o F1: Projection on the manifold surface
o F2: Steering towards the desired position
21 Camera shots - Motion
22 Camera shots - Demonstration
23 Cinematic replay
Cinematic replay Edit the camera rushes
Camera shots Animate the cameras
Camera specifications Retrieve the spec from the behaviors
Camera Behaviors
Target configuration Extract targets
Narrative importance Compute characters’ narrative importance
Game Record the Scenario and Animations
Editing based on [Lino et al. 2011]
Implementation of cost functions to evaluate:
Shots
Cuts
Pacing
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Path finding in an editing graph
Cinematic replay
Results 25
Nothing For Dinner
3 cameras behaviors: First Person Camera Second Person Camera Master Shot
2 different styles: Style #1: Point Of View Shots Style #2: Over The Shoulder Shots
Camera 1 Camera 2 Camera 3
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Set of rules #1
Set of rules #2
Results
27 Results
28 Results
Limitations & Future work 29
Limitations
Requires narrative information from the game
No temporal ellipse or flashback
Future work
More camera styles
Validation and user studies
Real-time in-game cinematography
Conclusion 30
Our narratively-driven system:
Automatically generates cinematic replays of game sessions
Works with large action vocabularies
Smoothly animates cameras that cut well together
Thank you for your attention!
31 Questions
