Procedural generation

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One example of procedural generation, here used to generate realistic looking tree models. Different models can be generated by changing both deterministic parameters and a random seed. Dragon trees.jpg
One example of procedural generation, here used to generate realistic looking tree models. Different models can be generated by changing both deterministic parameters and a random seed.

In computing, procedural generation is a method of creating data algorithmically as opposed to manually, typically through a combination of human-generated assets and algorithms coupled with computer-generated randomness and processing power. In computer graphics, it is commonly used to create textures and 3D models. In video games, it is used to automatically create large amounts of content in a game. Depending on the implementation, advantages of procedural generation can include smaller file sizes, larger amounts of content, and randomness for less predictable gameplay. Procedural generation is a branch of media synthesis.

Contents

Overview

A procedural landscape rendered in Terragen Terragen.jpg
A procedural landscape rendered in Terragen

The term procedural refers to the process that computes a particular function. Fractals are geometric patterns which can often be generated procedurally. Commonplace procedural content includes textures and meshes. Sound is often also procedurally generated, and has applications in both speech synthesis as well as music. It has been used to create compositions in various genres of electronic music by artists such as Brian Eno who popularized the term "generative music". [1]

While software developers have applied procedural generation techniques for years, few products have employed this approach extensively. Procedurally generated elements have appeared in earlier video games: The Elder Scrolls II: Daggerfall takes place in a mostly procedurally generated world, giving a world roughly two thirds the actual size of the British Isles. Soldier of Fortune from Raven Software uses simple routines to detail enemy models, while its sequel featured a randomly-generated level mode. Avalanche Studios employed procedural generation to create a large and varied group of detailed tropical islands for Just Cause . No Man's Sky , a game developed by games studio Hello Games, is all based upon procedurally generated elements.

The modern demoscene uses procedural generation to package a great deal of audiovisual content into relatively small programs.

New methods and applications are presented annually in conferences such as the IEEE Conference on Computational Intelligence and Games and Artificial Intelligence and Interactive Digital Entertainment. [2]

Particularly in the application of procedural generation with video games, which are intended to be highly replayable, there are concerns that procedural systems can generate infinite numbers of worlds to explore, but without sufficient human guidance and rules to guide these. The result has been called "procedural oatmeal", a term coined by writer Kate Compton, in that while it is possible to mathematically generate thousands of bowls of oatmeal with procedural generation, they will be perceived to be the same by the user, and lack the notion of perceived uniqueness that a procedural system should aim for. [3]

Contemporary application

Tabletop role-playing games

Using procedural generation in games had origins in the tabletop role playing game (RPG) venue. [4] The leading tabletop system, Advanced Dungeons & Dragons , provided ways for the "dungeon master" to generate dungeons and terrain using random die rolls, expanded in later editions with complex branching procedural tables. Strategic Simulations under license from TSR released the Dungeon Master's Assistant, a computer program that generated dungeons based on these published tables. Tunnels & Trolls , also published by TSR, was designed primarily around solitary play and used similar procedural generation for its dungeons. Other tabletop RPGs borrowed similar concepts in procedural generation for various world elements. [5]

Many online tools for Dungeon Masters now use procedural generation to varying degrees.[ citation needed ]

Video games

Early history

A procedurally generated dungeon map in the videogame NetHack Nethackscreen.gif
A procedurally generated dungeon map in the videogame NetHack

Prior to graphically oriented video games, roguelike games, a genre directly inspired by Dungeons & Dragons adopted for solitaire play, heavily utilized procedural generation in the same manner that tabletop systems had done. Such early games include Beneath Apple Manor (1978) and the genre's namesake, Rogue (1980). The procedural generation system in roguelikes would create dungeons in ASCII- or regular tile-based systems and define rooms, hallways, monsters, and treasure to challenge the player. Roguelikes, and games based on the roguelike concepts, allow the development of complex gameplay without having to spend excessive time in creating a game's world. [6]

1978's Maze Craze for the Atari VCS used an algorithm to generate a random, top-down maze for each game. [7]

Some games used pseudorandom number generators. These PRNGs were often used with predefined seed values in order to generate very large game worlds that appeared to be premade. The Sentinel supposedly had 10,000 different levels stored in only 48 and 64 kilobytes. An extreme case was Elite , which was originally planned to contain a total of 248 (approximately 282 trillion) galaxies with 256 solar systems each. However, the publisher was afraid that such a gigantic universe would cause disbelief in players, and eight of these galaxies were chosen for the final version. [8] Other notable early examples include the 1985 game Rescue on Fractalus that used fractals to procedurally create, in real time, the craggy mountains of an alien planet and River Raid , the 1982 Activision game that used a pseudorandom number sequence generated by a linear feedback shift register in order to generate a scrolling maze of obstacles.

Modern use

Procedural texture using Voronoi tessellation Blender3D VoronoiCrackle.jpg
Procedural texture using Voronoi tessellation

Though modern computer games do not have the same memory and hardware restrictions that earlier games had, the use of procedural generation is frequently employed to create randomized games, maps, levels, characters, or other facets that are unique on each playthrough. [9] [10]

In 2004, a PC first-person shooter called .kkrieger was released by a German demo group. It is entirely contained in a 96 kilobyte executable for Microsoft Windows that generates hundreds of megabytes of 3D and texture data when run. According to one of the programmers, "it was a complete failure as far as the game side was concerned (mostly because no one involved really deeply cared about that aspect)." [11]

Naked Sky's RoboBlitz used procedural generation to maximize content in a less than 50 MB downloadable file for Xbox Live Arcade. Will Wright's Spore also makes use of procedural synthesis.

Procedural generation is often used in loot systems of quest-driven games, such as action role-playing games and massive multiplayer online role playing games. Though quests may feature fixed rewards, other loot, such as weapons and armor, may be generated for the player based on the player-character's level, the quest's level, their performance in the quest, and other random factors. This often leads to loot having a rarity quality applied to reflect when the procedural generation system has produced an item with better-than-average attributes. For example, the Borderlands series is based on its procedural generation system which can create over a million unique guns and other equipment. [12]

Many open world or survival games procedurally create a game world from a random seed or one provided by the player, so that each playthrough is different. These generation systems create numerous pixel- or voxel-based biomes with distribution of resources, objects, and creatures. The player frequently has the ability to adjust some of the generation parameters, such as specifying the amount of water coverage in a world. Examples of such games include Dwarf Fortress and Minecraft . An artifact of the procedural generation around these games is that if the space that the player is allowed to explore is not limited, the randomness of the procedural generation will start to produce more noise than content; this is exemplified in the idea of the "Far Lands" within some earlier versions of Minecraft, where the usual smooth transitions between biomes was replaced with haphazard formations. [13]

Procedural generation is also used in space exploration and trading games. Elite: Dangerous , through using the 400 billion known stars of the Milky Way Galaxy as its world basis, uses procedural generation to simulate the planets in these solar systems. Similarly, Star Citizen uses the technology for its planets, to create a collection of seamlessly-loaded planet-sized planets among its hand-crafted universe. I-Novae Infinity features a plethora of planets which are procedurally generated between which the player can travel via space ships. Outerra Anteworld is a video game in development that uses procedural generation and real world data to create a virtual replica of planet Earth in true scale. No Man's Sky features a universe containing 18 quintillion planets which are procedurally generated on the fly as the player encounters them, including their terrain, weather, flora, and fauna, as well as a number of space-faring alien species. This universe is defined by the use of a single random seed number to their deterministic engine, assuring that the same content will be generated at the same places for all players, which enables players to share discoveries using only knowledge of the locations of the planets in the virtual galaxy. [14] [15]

Film

As in video games, procedural generation is often used in film to create visually interesting and accurate spaces rapidly. This comes in a wide variety of applications.

One application is known as an imperfect factory, where artists can rapidly generate many similar objects. This accounts for the fact that, in real life, no two objects are ever exactly alike. For instance, an artist could model a product for a grocery store shelf, and then create an imperfect factory to generate many similar objects to populate the shelf.

MASSIVE is a high-end computer animation and artificial intelligence software package used for generating crowd-related visual effects for film and television. It was developed to create fighting armies of hundreds of thousands of soldiers for Peter Jackson's The Lord of the Rings films automatically. [16]

Coherent noise can be extremely important to procedural workflow in film. Simplex noise is often faster with fewer artifacts, though an older function called Perlin noise may be used as well. Coherent noise, in this case, refers to a function that generates smooth pseudo-randomness in n dimensions.

The landscapes in The Mandalorian are produced on the fly using a modified Unreal Engine 4 and LEDs for projection of the result which is being filmed in real time to show accurate reflections on the set. [17] [18]

See also

Related Research Articles

<i>NetHack</i> Classical roguelike ASCII graphics computer game released in 1987

NetHack is an open source single-player roguelike video game, first released in 1987 and maintained by the NetHack DevTeam. The game is a software fork of the 1982 game Hack, itself inspired by the 1980 game Rogue. The player takes the role as one of several pre-defined character classes to descend through multiple dungeon floors, fighting monsters and collecting treasure, to recover the "Amulet of Yendor" at the lowest floor and then escape. As a traditional roguelike, NetHack features procedural-generated dungeons and treasure, hack and slash combat, tile-based gameplay, and permadeath, forcing the player to restart anew should their character die. While Rogue, Hack and other earlier roguelikes stayed true to a high fantasy setting, NetHack introduced humorous and anachronistic elements over time, including popular cultural reference to works such as Discworld and Raiders of the Lost Ark.

Roguelike Subgenre of role-playing video games

Roguelike is a subgenre of role-playing video games characterized by a dungeon crawl through procedurally generated levels, turn-based gameplay, grid-based movement, and permanent death of the player character. Most roguelikes are based on a high fantasy narrative, reflecting their influence from tabletop role playing games such as Dungeons & Dragons.

<i>Moria</i> (1983 video game)

The Dungeons of Moria, usually referred to as just Moria, is a computer game inspired by J. R. R. Tolkien's novel The Lord of the Rings. The objective of the game is to dive deep into the Mines of Moria and kill the Balrog. Moria, along with Hack (1984), and Larn (1986), is considered to be the first roguelike game, and the first to include a town level.

<i>Rogue</i> (video game) 1980 video game

Rogue is a dungeon crawling video game by Michael Toy and Glenn Wichman and later contributions by Ken Arnold. Rogue was originally developed around 1980 for Unix-based mainframe systems as a freely-distributed executable. It was later included in the official Berkeley Software Distribution 4.2 operating system (4.2BSD). Commercial ports of the game for a range of personal computers were made by Toy, Wichman, and Jon Lane under the company A.I. Design and financially supported by the Epyx software publishers. Additional ports to modern systems have been made since by other parties using the game's now-open source code.

Perlin noise Type of gradient noise in computer graphics

Perlin noise is a type of gradient noise developed by Ken Perlin.

Dungeon crawl

A dungeon crawl is a type of scenario in fantasy role-playing games in which heroes navigate a labyrinth environment, battling various monsters, avoiding traps, solving puzzles, and looting any treasure they may find. Video games which predominantly feature dungeon crawl elements are considered to be a genre.

Ken Perlin

Kenneth H. Perlin is a professor in the Department of Computer Science at New York University, founding director of the Media Research Lab at NYU, director of the Future Reality Lab at NYU, and the Director of the Games for Learning Institute. His research interests include graphics, animation, multimedia, and science education. He developed or was involved with the development of techniques such as Perlin noise, hypertexture, real-time interactive character animation, and computer-user interfaces such as zooming user interfaces, stylus-based input (Quikwriting), and most recently, cheap, accurate multi-touch input devices. He is also the Chief Technology Advisor of ActorMachine, LLC.

A random dungeon is a dungeon in a role-playing video game which is procedurally generated by the computer using an algorithm, such that the dungeon is laid out differently every time the player enters it, and a player often never plays through quite the same dungeon twice, as there are innumerable possibilities for how they generate.

Procedural modeling is an umbrella term for a number of techniques in computer graphics to create 3D models and textures from sets of rules. L-Systems, fractals, and generative modeling are procedural modeling techniques since they apply algorithms for producing scenes. The set of rules may either be embedded into the algorithm, configurable by parameters, or the set of rules is separate from the evaluation engine. The output is called procedural content, which can be used in computer games, films, be uploaded to the internet, or the user may edit the content manually. Procedural models often exhibit database amplification, meaning that large scenes can be generated from a much smaller number of rules. If the employed algorithm produces the same output every time, the output need not be stored. Often, it suffices to start the algorithm with the same random seed to achieve this.

Scenery generator Type of software

A scenery generator is software used to create landscape images, 3D models, and animations. These programs often use procedural generation to generate the landscapes. If not using procedural generation to create the landscapes, then normally a 3D artist would render and create the landscapes. These programs are often used in video games or movies. Basic elements of landscapes created by scenery generators include terrain, water, foliage, and clouds. The process for basic random generation uses a diamond square algorithm.

Value noise Type of noise in computer graphics

Value noise is a type of noise commonly used as a procedural texture primitive in computer graphics. It is conceptually different from, and often confused with gradient noise, examples of which are Perlin noise and Simplex noise. This method consists of the creation of a lattice of points which are assigned random values. The noise function then returns the interpolated number based on the values of the surrounding lattice points.

Procedural texture

In computer graphics, a procedural texture is a texture created using a mathematical description rather than directly stored data. The advantage of this approach is low storage cost, unlimited texture resolution and easy texture mapping. These kinds of textures are often used to model surface or volumetric representations of natural elements such as wood, marble, granite, metal, stone, and others.

<i>Dragon Fin Soup</i>

Dragon Fin Soup is an action role-playing video game created by the independent development studio Grimm Bros. It is the studio's first title and was released on Microsoft Windows, PlayStation 4, PlayStation 3, and PlayStation Vita. It is influenced by roguelike games and uses procedural generation for parts of the game. The game has two modes: Story mode follows a story and is more like a typical role-playing game, while Survival mode skips the story and focuses on the surviving within the game and constrains players with permadeath—once the player character dies, the game must be restarted from the beginning.

<i>Dungeon of the Endless</i>

Dungeon of the Endless is a roguelike tower defense game developed by Amplitude Studios. It is the third game of their loosely connected Endless series, which includes Endless Space and Endless Legend. It was released in October 2014 for Microsoft Windows and Mac OS X systems, August 2015 for iOS devices, and for Xbox One in March 2016. The PlayStation 4 and Nintendo Switch ports were released in May 2020. A revamped version for iOS and Android devices, called Dungeon of the Endless: Apogee, launched on March 16, 2021.

Map seed Number or string used to procedurally generate a game world

In video games using procedural world generation, the map seed is a (relatively) short number or text string which is used to procedurally create the game world ("map"). This means that while the seed-unique generated map may be many megabytes big, it is possible to reset to the unmodified map, or the unmodified map can be exchanged between players, just by specifying the map seed. An example of a map seed in Minecraft is "-2242547518357798464". Map seeds are a type of random seeds.

No Man's Sky is a 2016 video game developed by the British development studio, Hello Games. No Man's Sky allows the player to partake in four principal activities—exploration, survival, combat, and trading—in a shared, deterministic, procedurally generated open universe, which contains over 18 quintillion planets each with their own unique environment and flora and fauna.

A roguelike deck-building game is a hybrid genre of video games that combine the nature of deck-building card games with procedural-generated randomness from roguelike games.

<i>Caves of Qud</i>

Caves of Qud is an Early Access roguelike role-playing video game. Set in an open world, the world is partially pre-made and partially randomly generated. The game takes place in a post-apocalyptic science fantasy setting and is inspired by the pen-and-paper role-playing games Gamma World and Dungeons & Dragons.

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Further reading