Semantic constraints for procedural generation of virtual worlds

Abstract

Procedural generation of virtual worlds is a promising alternative to classical manual modelling approaches, which usually require a large amount of effort and expertise. However, it suffers from a number of issues; most importantly, the lack of user control over the generation process and its outcome. Because of this, the result of a procedural method is highly unpredictable, rendering it almost unusable for virtual world designers.This paper focuses on providing user control to deliver an outcome consistent with designer's intent. For this, we introduce semantic constraints, a flexible concept to express high-level designer's intent in intuitive terms as e.g. line of sight. Our constraint evaluation method is capable of detecting the context in which such a constraint is specified, automatically adapting to surrounding features of the virtual world. From experiments performed within our prototype modelling system, we can conclude that semantic constraints are another step forward in making procedural generation of virtual worlds more controllable and accessible to nonspecialist designers.

Quantifiable Isovist and Graph-Based Measures for Automatic Evaluation of Different Area Types in Virtual Terrain Generation

“…Although designed for creating game levels, this approach still requires a large amount of user input with desired game design elements having to be manually expressed by the user in the sketch. Another technique proposed by Smelik et al [40] used two types of constraints to control the generation process of virtual worlds: semantic constraints and feature constraints. Feature constraint is linked to a single feature in the terrain (e.g.…”

“…Andereck's [38] work focused on generating terrain to conform to a desired path, which may be useful as a terrain generation component, but is still far from being a complete terrain level generator that incorporates gameplay elements. Smelik's approach includes game design in a terrain and uses semantic constraints that can interact with the terrain to ensure it meets the desired design of a user [40]. Their results showed that using semantic constraints is a viable approach towards incorporating gameplay elements in terrain generation, but their approach is not scalable.…”

Understanding procedural content generation

“…The challenge with constraint-based approaches comes largely in determining an appropriate representation for facts about the generated content, and with debugging a set of complex, interrelated constraints. This approach has been used extensively in tools for designers [4,46,52].…”

“…Direct manipulation involves the player actively altering the generated content to provide additional constraints to the generator. This form of manipulation is more commonly seen in PCG-enabled design tools [46,52], rather than games themselves. The Spore Creature Creator [26], a design tool offered as part of the game Spore [27], offers this kind of interaction.…”

A framework to design 3D interaction assistance in constraints-based virtual environments

“…It is composed of "feature sub-constraints" mapped to low-level operations (e.g. the height of trees) [37]. Indeed, constraints are not always geometric or even virtual: table 1 shows a list of possible issues, situations or requirements which can have a constraining influence on VR interactions.…”