Editing Crowd simulation (section)

== History ==
There has always been a deep-seated interest in the understanding and gaining control of motional and behavior of crowds of people. Many major advancements have taken place since the beginnings of research within the realm of crowd simulation. Evidently many new findings are continually made and published following these which enhance the scalability, flexibility, applicability, and realism of simulations:

In 1987, behavioral animation was introduced and developed by [[Craig Reynolds (computer graphics)|Craig Reynolds]].<ref>{{cite book |doi=10.1145/37401.37406 |chapter=Flocks, herds and schools: A distributed behavioral model |title=Proceedings of the 14th annual conference on Computer graphics and interactive techniques |date=1987 |last1=Reynolds |first1=Craig W. |pages=25–34 |isbn=0-89791-227-6 |url=http://elartu.tntu.edu.ua/handle/lib/43005 }}</ref> He had simulated flocks of birds alongside schools of fish for the purpose of studying group intuition and movement. All agents within these simulations were given direct access to the respective positions and velocities of their surrounding agents. The theorization and study set forth by Reynolds was improved and built upon in 1994 by [[Xiaoyuan Tu]], [[Demetri Terzopoulos]] and Radek Grzeszczuk.<ref>{{cite journal |last1=Terzopoulos |first1=Demetri |last2=Tu |first2=Xiaoyuan |last3=Grzeszczuk |first3=Radek |title=Artificial Fishes: Autonomous Locomotion, Perception, Behavior, and Learning in a Simulated Physical World |journal=Artificial Life |date=July 1994 |volume=1 |issue=4 |pages=327–351 |doi=10.1162/artl.1994.1.4.327 }}</ref> The realistic quality of simulation was engaged with as the individual agents were equipped with synthetic vision and a general view of the environment within which they resided, allowing for a perceptual awareness within their dynamic habitats.

Initial research in the field of crowd simulation began in 1997 with [[Daniel Thalmann]]'s supervision of Soraia Raupp Musse's PhD thesis. They present a new model of crowd behavior in order to create a simulation of generic populations.<ref>{{Cite book|url=https://books.google.com/books?id=3Adh_2ZNGLAC&q=history+of+crowd+simulation&pg=PR8|title=Crowd Simulation|last1=Thalmann|first1=Daniel|last2=Musse|first2=Soraia Raupp|date=2012-10-04|publisher=Springer Science & Business Media|isbn=978-1-4471-4449-6|language=en}}</ref> Here a relation is drawn between the autonomous behavior of the individual within the crowd and the emergent behavior originating from this.<ref>{{cite book |doi=10.1007/978-3-7091-6874-5_3 |chapter=A Model of Human Crowd Behavior : Group Inter-Relationship and Collision Detection Analysis |title=Computer Animation and Simulation '97 |url=https://archive.org/details/computeranimatio1997bode |url-access=limited |pages=[https://archive.org/details/computeranimatio1997bode/page/n46 39]–51 |series=Eurographics |year=1997 |last1=Musse |first1=S. R. |last2=Thalmann |first2=D. |isbn=978-3-211-83048-2 }}</ref>

In 1999, individualistic navigation began its course within the realm of crowd simulation via continued research of Craig Reynolds.<ref>{{Cite web|url=http://www.red3d.com/cwr/papers/1999/gdc99steer.html|title=Steering Behaviors For Autonomous Characters|website=www.red3d.com|access-date=2016-12-17}}</ref> Steering behaviors are proven to play a large role in the process of automating agents within a simulation. Reynolds states the processes of low-level locomotion to be dependent and reliant on mid-level steering behaviors and higher-level goal states and path finding strategies. Building off of the advanced work of Reynolds, Musse and Thalmann began to study the modeling of [[real-time simulation|real time simulation]]s of these crowds, and their applications to human behavior. The control of human crowds was designated as a hierarchical organization with levels of autonomy amongst agents. This marks the beginnings of modeling individual behavior in its most elementary form on humanoid agents or [[virtual humans]].<ref>{{cite journal |doi=10.1109/2945.928167 |title=Hierarchical model for real time simulation of virtual human crowds |journal=IEEE Transactions on Visualization and Computer Graphics |volume=7 |issue=2 |pages=152–64 |year=2001 |last1=Musse |first1=S.R. |last2=Thalmann |first2=D. |url=http://infoscience.epfl.ch/record/98931 |type=Submitted manuscript }}</ref>

Coinciding with publications regarding human behavior models and simulations of group behaviors, Matt Anderson, Eric McDaniel, and Stephen Chenney's proposal of constraints on behavior<ref>{{Cite news|author1=Matt Anderson|author2=Eric McDaniel|author3=Stephen Chenney|title=Constrained animation of flocks|publisher=SCA '03 Proceedings of the 2003 ACM SIGGRAPH/Eurographics symposium on Computer animation |pages= 286–297|date=July 26–27, 2003 |isbn=1-58113-659-5 }}</ref> gained popularity. The positioning of constraints on group animations was presented to be able to be done at any time within the simulation. This process of applying constraints to the behavioral model is undergone in a two-fold manner, by first determining the initial set of goal trajectories coinciding with the constraints, and then applying behavioral rules to these paths to select those which do not violate them.

Correlating and building off of the findings proposed in his work with Musse, Thalmann, working alongside Bratislava Ulicny and Pablo de Heras Ciechomski, proposed a new model which allowed for interactive authoring of agents at the level of an individual, a group of agents and the entirety of a crowd. A brush metaphor is introduced to distribute, model and control crowd members in real-time with immediate feedback.<ref>{{cite book |doi=10.1145/1028523.1028555 |chapter=Crowdbrush |title=Proceedings of the 2004 ACM SIGGRAPH/Eurographics symposium on Computer animation – SCA '04 |pages=243–52 |year=2004 |last1=Ulicny |first1=Branislav |last2=Ciechomski |first2=Pablo de Heras |last3=Thalmann |first3=Daniel |isbn=978-3-905673-14-2 |url=http://infoscience.epfl.ch/record/100256 }}</ref>