Procedural feature generation for volumetric terrains using voxel grammars

© 2018 Terrain generation is a fundamental requirement of many computer graphics simulations, including computer games, flight simulators and environments in feature films. There has been a considerable amount of research in this domain, which ranges between fully automated and semi-automated methods. Voxel representations of 3D terrains can create rich features that are not found in other forms of terrain generation techniques, such as caves and overhangs. In this article, we introduce a semi-automated method of generating features for volumetric terrains using a rule-based procedural generation system. Features are generated by selecting subsets of a voxel grid as input symbols to a grammar, composed of user-created operators. This results in overhangs and caves generated from a set of simple rules. The feature generation runs on the CPU and the GPU is utilised to extract a robust mesh from the volumetric dataset

Procedural feature generation for volumetric terrains

© 2017 Copyright held by the owner/author(s). In this work we present separate procedural methods to generate features that are found in natural terrains which are difficult to reproduce with heightmap-based methods. We approximate overhangs, arches and caves using procedural functions and a reduced set of parameters. This produces visually plausible terrain feature topologies as well as a high degree of artistic control. Our approach is more intuitive and art-directable than other existing volumetric methods that are more complex to integrate into existing voxel engines, due to the framework changes necessary, or rely on automatic procedural generation, thus reducing the ability to provide creative input

Procedural generation of features for volumetric terrains using a rule-based approach.

Terrain generation is a fundamental requirement of many computer graphics simulations, including computer games, flight simulators and environments in feature films. Volumetric representations of 3D terrains can create rich features that are either impossible or very difficult to construct in other forms of terrain generation techniques, such as overhangs, arches and caves. While a considerable amount of literature has focused on procedural generation of terrains using heightmap-based implementations, there is little research found on procedural terrains utilising a voxel-based approach. This thesis contributes two methods to procedurally generate features for terrains that utilise a volumetric representation. The first method is a novel grammar-based approach to generate overhangs and caves from a set of rules. This voxel grammar provides a flexible and intuitive method of manipulating voxels from a set of symbol/transform pairs that can provide a variety of different feature shapes and sizes. The second method implements three parametric functions for overhangs, caves and arches. This generates a set of voxels procedurally based on the parameters of a function selected by the user. A small set of parameters for each generator function yields a widely varied set of features and provides the user with a high degree of expressivity. In order to analyse the expressivity, this thesis’ third contribution is an original method of quantitatively valuing a result of a generator function. This research is a collaboration with Sony Interactive Entertainment and their proprietary game engine PhyreEngineTM. The methods presented have been integrated into the engine’s terrain system. Thus, there is a focus on real-time performance so as to be feasible for game developers to use while adhering to strict sub-second frame times of modern computer games

Methods for Procedural Terrain Generation

Procedural generation has been utilized in the automatic generation of data for a long time. This automated processing has been utilized in the entertainment industry as well as in research work in order to be able to quickly produce large amounts of just the kind of data needed, for example, in system testing. In this thesis, we examine different ways to utilize procedural generation to produce different synthetic terrains. First, we will take a closer look at what procedural generation is, where it originally started, and where it was utilized. From this we move on to look at how this technology is utilized in the creation of terrains and what terrain is generally visually required. From this we move on to look at different ways to implement terrain generation. As part of this thesis, we have selected three methods and implemented our own implementations for terrain generation. We look at the performance of these implementations, and what a test group thinks about those synthetic terrains. The results obtained from this are analyzed and presented at the end of the thesis.Proseduraalista generointia on hyödynnetty datan automaattisessa tuottamisessa jo pitkään. Tätä automatisoitua prosessointia on niin hyödynnetty viihdeteollisuudessa kuin tutkimustyössä, jotta ollaan voitu tuottaa nopeasti suuria määriä juuri sellaista dataa kuin tarvitaan esimerkiksi järjestelmän testauksessa. Tässä tutkielmassa tarkastellaan erilaisia tapoja hyödyntää proseduraalista generointia erilaisten synteettisten maastojen tuottamiseksi. Aluksi tutustutaan hieman tarkemmin siihen mitä proseduraalinen generointi on, mistä se on alunperin lähtenyt ja mihin sitä on hyödynnetty. Tästä siirrytään tarkastelemaan miten kyseistä tekniikkaa hyödynnetään maastojen luomisessa ja mitä maastoilta yleensä visuaalisesti vaaditaan. Tästä siirrytään tarkastelemaan eri tapoja toteuttaa maaston generointia. Osana tätä tutkielmaa, on valittu kolme menetelmää ja laadittu niistä kullekin oma toteutus maaston generointiin. Työssä tarkastellaan näiden toteutusten suoritustuloksia, ja mitä mieltä testiryhmä on kyseisistä synteettisistä maastoista. Saadut tulokset ja niiden analyyysi esitellään tutkielman lopussa

Procedural 3D Caves, Clouds and Architecture Generation Method Based on Shape Grammar and Morphing

This paper presents a new procedural 3D modelconstructionalgorithm that benefits from a combination ofdiscrete and continuous modeling approaches. Our algorithmmodels complex scene components such as caves, architecturalbuildings, and clouds. The method combines the discretedescriptiveness of shape grammars with the continuous flexibilityof shape morphing. This combination allows for a modelingapproach that can be controlled by a morphing parameter toproduce various types of geometry. In the paper, we focus on thedescription of the algorithm while also showing its capabilities ingenerating complex scene components

Real-time rendering and physics of complex dynamic terrains modeled as CSG trees of DEMs carved with spheres

We present a novel proposal for modeling complex dynamic terrains that offers real-time rendering, dynamic updates and physical interaction of entities simultaneously. We can capture any feature from landscapes including tunnels, overhangs and caves, and we can conduct a total destruction of the terrain. Our approach is based on a Constructive Solid Geometry tree, where a set of spheres are subtracted from a base Digital Elevation Model. Erosions on terrain are easily and efficiently carried out with a spherical sculpting tool with pixel-perfect accuracy. Real-time rendering performance is achieved by applying a one-direction CPU–GPU communication strategy and using the standard depth and stencil buffer functionalities provided by any graphics processor.This work has been partially funded by Ministeri de Ciència i Innovació (MICIN), Agencia Estatal de Investigación (AEI) and the Fons Europeu de Desenvolupament Regional (FEDER) (project PID2021-122136OB-C21 funded by MCIN/AEI/10.13039/50110001 1033/FEDER, UE).Postprint (published version

Shape Metamorphosis – Automatic 3D Mesh Generation, Topology Verification and Analysis

The objective of this paper is a 3D shape construction that benefits from discrete and continuous modelling approaches. The proposed solution addresses the problem of automated modelling of virtual structures such as caves, buildings and clouds and presents an alternative solution in the form of a hybrid system. Parallel realizations of these solutions are tested on various processors of graphic cards with the use of NVIDIA ‘CUDA’ technology. This paper describes the implementation of algorithms (approaches) and their parallel speedup, efficiency, throughput. Modelled structures are geometrically complex, with an inner graph structure more optimized than in the classical CSG approach. Moreover, they can be rendered up to very high levels of visual realism. In this paper we mainly focus on the description of the algorithm. We also propose very useful measures that can be used to verify the model geometry

Procedural Generation of Voxel Worlds with Castles

This thesis explores procedurally creating voxel based terrains and creating castles in them. With the explosion of interest in using voxels in games since the success of Minecraft, and even big budget titles like EverQuest Next using this technology, this research aims to address an area that has not received adequate attention: procedural generation of buildings like castles. By utilizing voxels combined with procedural generation of terrain, games like Minecraft and its many clones are able to offer worlds of near limitless size for the player to explore. However, this presents a challenge: how to fill a world with content worth exploring; primarily structures that look human-made. This project focuses on perhaps the most iconic of fantasy game structures: the castle. A voxel world engine was developed to explore this problem, complete with a procedural terrain generator similar to that used in voxel world games. The terrain generator developed for this project is capable of creating a variety of terrains randomly to test castle placement and generation. By drawing inspiration from real castles construction algorithms were developed to analyze areas of voxel terrain for good castle positioning and adaptive layout of a castle to the terrain. This was used to procedurally generate castles that aim to look as though they were placed into the world by a human agent

Procedural Generation of 3D Caves for Games on the GPU

Procedural Content Generation in Games (PCG) is a thriv- ing field of research and application. Recent presented ex- amples range from levels, stories and race tracks to complete rulesets for games. However, there is not much research to date on procedural 3D modeling of caves, and similar en- closed natural spaces. In this paper, we present a modular pipeline to procedurally generate underground caves in real- time, to be used as part of larger landscapes in game worlds. We propose a three step approach, which can be fully im- plemented using General-Purpose Computing on Graphics Processing (GPGPU) technology: 1) an L-System to em- ulate the expanded cracks and passages which form cave structures in nature, 2) a noise-perturbed metaball approach for virtual 3D carving, and 3) a rendering component for isosurface extraction of the modeled voxel data, and fur- ther mesh enhancement through shader programming. We demonstrate how the interaction between these components produce results comparable to real world caves, and show that the solution is viable for video game environments. For this, we present the findings of a user study we conducted among indie-game developers and players, using our results

Quantifiable isovist and graph-based measures for automatic evaluation of different area types in virtual terrain generation

© 2013 IEEE. This article describes a set of proposed measures for characterizing areas within a virtual terrain in terms of their attributes and their relationships with other areas for incorporating game designers\u27 intent in gameplay requirement-based terrain generation. Examples of such gameplay elements include vantage point, strongholds, chokepoints and hidden areas. Our measures are constructed on characteristics of an isovist, that is, the volume of visible space at a local area and the connectivity of areas within the terrain. The calculation of these measures is detailed, in particular we introduce two new ways to accurately and efficiently calculate the 3D isovist volume. Unlike previous research that has mainly focused on aesthetic-based terrain generation, the proposed measures address a gap in gameplay requirement-based terrain generation-the need for a flexible mechanism to automatically parameterise specified areas and their associated relationships, capturing semantic knowledge relating to high level user intent associated with specific gameplay elements within the virtual terrain. We demonstrate applications of using the measures in an evolutionary process to automatically generate terrains that include specific gameplay elements as defined by a game designer. This is significant as this shows that the measures can characterize different gameplay elements and allow gameplay elements consistent with the designers\u27 intents to be generated and positioned in a virtual terrain without the need to specify low-level details at a model or logic level, hence leading to higher productivity and lower cost