ARTIFICIAL
CITY
A TRAFFIC SIMULATION
INSPIRATION
CitiesXL
SimCity
4
http://forum.citiesxl.com/viewtopic.php?f=58&t=32
98
http://www.centgraf.net/metroviz/r_external.html
INSPIRATION
GTA
IV
Transport
Tycoon
http://rockstarhq.multiplayernetwork.net/news/2067/
http://abdussamad.com/archives/60-Classicstrategy-gaming-with-Transport-Tycoon.html
INDUSTRY CONTEXT
Transmodeler
SUMO
http://www.caliper.com/transmodeler/
http://sumo.sourceforge.net/
BRIEF
To build a traffic simulator
BREAKING DOWN
Vehicles will need to react to each other
More than one vehicle at a time
Need mechanism to guide
vehicles between them
Multiple road elements
Vehicles travel on roads
You travel to a location
Need mechanism to guide to goal
REQUIREMENTS
A road network to navigate in
relation to
Multiple vehicles with separate
destinations that can react to each
other
A means for vehicles to move
locate and reach their destination
DESIGN DECISIONS
Network generation?
2D vs. 3D
Grid vs. Free-form
Language?
Metadata?
Complexity
DESIGN DECISIONS
Network generation?
2D vs. 3D
2D
Pre-coded Scenarios
Grid vs. Free-form
Free-form
Language?
C#
Metadata?
Not beyond performance
Complexity
Fixed vehicle attributes
FREE-FORM ROADS
Join the Dots
Time expensive to design large networks this way
System can speed process by calculating roads itself
ROAD “STRIP”
Two coordinates held in
association
Use offset values to
render as a stretch of
tarmac
Smallest linear component of a road that may be curved
Place together to represent curves
MULTIPLE DIRECTION
ROADS
Issues with interpolating the nodes
Made worse by sharp corners and multiple lanes
Issues with smoothing
SHARP CORNERS
Road width increasing at corners
SMOOTHING
CORNERS
Unequal number of lane elements
Loss of relation to node
VEHICLE CONCEPTS
Components govern
performance
Occupant governs
behaviours
PERFORMANCE
Acceleration/Speed
depend on power and
weight
Cornering depends on
brakes and chassis
BEHAVIOURS
Severity of Acceleration/Deceleration
Stopping Distance
Lane changing behaviours
Comfortable top speed
Depends on Driver
Sometimes feelings,
such as stress or impatience
Other times as preference or habit
BASIC MOVEMENT
Move towards target node
For example, one from a road “strip”.
Don’t collide with other vehicles
Try to match pace
MORE COMPLEX
INTERACTIONS
Attempt to bypass obstructions
Beware of new vehicles which might present collision risks
FUZZY LOGIC
Multi-value approach to logic
Decimal based membership of values
Represent Driver as collection of fuzzy sets
Supply situational information and de-fuzzify
key values to determine decisions
LANE CHANGE EXAMPLE
 Driver waits at the back of queue for lights to change
 The driver method processes that the adjacent lane has a cars length of
space
 Potential Space > Car Length
 The adjacent lane has no streaming controls, thus the driver can continue on
a direct route to their destination from it
 Route suitability is true
 The driver has a low membership value to the Impatience fuzzy set, but
currently possesses a high membership to the Stress set which has been
increasing due to not reaching locations as rapidly as the path-finding
algorithm expected them to.
 The de-fuzzified value combined with the earlier variables passes the
threshold value and the car maneuvers into the free space
PREREQUISITES
 The more freedom of navigation an automated element is given
the greater the scope for error
 This can be managed by properly training the automated
elements before declaring the simulation finalised
 Movement of vehicles with relation to nodes requires a finalised
network structure
ROUTE-PLANNING
The means of determining the shortest route from point A to point B