Modeling of an evolving river network with meanders, oxbow lakes and river deltas

Kurowski, Michał

Modeling of an evolving river network with meanders, oxbow lakes and river deltas

Michał Kurowski

Abstract

Development of virtual worlds for use in computer games requires the creation of wast amounts of various content, including three-dimensional terrain. The approach in which the terrain is created manually by a level designer can be time-consuming. The alternative is to emploi procedural techniques, which unfortunately reduce the amount of control over the final results. Currently there is a tendency to combine both approaches by using procedural methods to enhance a manually prepared (e.g. as a sketch) terrain with features like mountains, lakes or rivers. The existing literature describes the creation of rivers using fractals, parametric methods or erosion simulation. The last approach usually has a high computational cost. However, due to its iterative nature, it can be used to present the process of terrain evolution itself. The existing methods rarely address the process of meandering, which is common in natural rivers. The thesis of this work is to show that is is possible to conceive a method of creation and development of meanders, which: • can be used on rivers with tributaries and deltas; • takes into account the emergence of oxbow lakes; • can be easily integrated with other methods of procedural terrain generation. In order to show the validity of the above-mentioned thesis, the author has developed a heuristic algorithm which can create a network of meandering rivers with deltas and can be used on an existing terrain. The presented approach can be integrated into a larger hybrid method used for creation of virtual worlds. It can also be employed in the mechanics of games that feature terrain evolution during gameplay. The proposed method represents river channels as polylines. Terrain is modeled as a triangle mesh. Meander growth is simulated in an iterative manner. For each river vertex a displacement vector is calculated based on the channel curvature, local terrain features and user-defined parameters. Tributaries, billabongs, lakes, river mouth switching and the emergence of wavedominated and tide-dominated deltas have been implemented. Additionally, a simple mountain generation algorithm has been proposed, which uses the data calculated during the meander modeling. A test environment which enables an interactive work with the implemented algorithms has been prepared. The analysis of the results has shown a similarity between the generated rivers and forms present in nature. According to the conducted survey the procedurally modeled river courses are visually attractive and difficult to differentiate from the natural ones.

Record ID

WUT880fba02fa4d4b7fba4963b91c2e1b8c

Diploma type

Doctor of Philosophy

Author

Michał Kurowski

Title in Polish

Modelowanie ewoluującej sieci rzecznej zawierającej meandry starorzecza i delty

Title in English

Modeling of an evolving river network with meanders, oxbow lakes and river deltas

Language

(pl) Polish

Certifying Unit

Faculty of Electronics and Information Technology (FEIT)

Discipline

information science / (technology domain) / (technological sciences)

Status

Finished

Start date

26-03-2013

Defense Date

10-03-2015

Title date

24-03-2015

Supervisor

Jan Zabrodzki

Internal reviewers

Tomasz Martyn

External reviewers

Konrad Wojciechowski

Pages

123

Keywords in English

terrain modeling, procedural content generation, PCG, river modeling, oxbow lakes,

Abstract in English

Development of virtual worlds for use in computer games requires the creation of wast amounts of various content, including three-dimensional terrain. The approach in which the terrain is created manually by a level designer can be time-consuming. The alternative is to emploi procedural techniques, which unfortunately reduce the amount of control over the final results. Currently there is a tendency to combine both approaches by using procedural methods to enhance a manually prepared (e.g. as a sketch) terrain with features like mountains, lakes or rivers. The existing literature describes the creation of rivers using fractals, parametric methods or erosion simulation. The last approach usually has a high computational cost. However, due to its iterative nature, it can be used to present the process of terrain evolution itself. The existing methods rarely address the process of meandering, which is common in natural rivers. The thesis of this work is to show that is is possible to conceive a method of creation and development of meanders, which: • can be used on rivers with tributaries and deltas; • takes into account the emergence of oxbow lakes; • can be easily integrated with other methods of procedural terrain generation. In order to show the validity of the above-mentioned thesis, the author has developed a heuristic algorithm which can create a network of meandering rivers with deltas and can be used on an existing terrain. The presented approach can be integrated into a larger hybrid method used for creation of virtual worlds. It can also be employed in the mechanics of games that feature terrain evolution during gameplay. The proposed method represents river channels as polylines. Terrain is modeled as a triangle mesh. Meander growth is simulated in an iterative manner. For each river vertex a displacement vector is calculated based on the channel curvature, local terrain features and user-defined parameters. Tributaries, billabongs, lakes, river mouth switching and the emergence of wavedominated and tide-dominated deltas have been implemented. Additionally, a simple mountain generation algorithm has been proposed, which uses the data calculated during the meander modeling. A test environment which enables an interactive work with the implemented algorithms has been prepared. The analysis of the results has shown a similarity between the generated rivers and forms present in nature. According to the conducted survey the procedurally modeled river courses are visually attractive and difficult to differentiate from the natural ones.

PKT classification