Integrating procedural generation and manual editing of virtual worlds

Abstract

Because of the increasing detail and size of virtual worlds, designers are more and more urged to consider employing procedural methods to alleviate part of their modeling work. However, such methods are often unintuitive to use, difficult to integrate, and provide little user control, making their application far from straightforward.In our declarative modeling approach, designers are provided with a more productive and simplified virtual world modeling workflow that matches better with their iterative way of working. Using interactive procedural sketching, they can quickly layout a virtual world, while having proper user control at the level of large terrain features. However, in practice, designers require a finer level of control. Integrating procedural techniques with manual editing in an iterative modeling workflow is an important topic that has remained relatively unaddressed until now.This paper identifies challenges of this integration and discusses approaches to combine these methods in such a way that designers can freely mix them, while the virtual world model is kept consistent during all modifications. We conclude that overcoming the challenges mentioned, for example in a declarative modeling context, is instrumental to achieve the much desired adoption of procedural modeling in mainstream virtual world modeling.

A declarative approach to procedural modeling of virtual worlds

“…However, as concluded in our recent survey [13], traditional procedural methods are not directly a suitable alternative to manual modeling. They typically lack any user control other than a set of, often unintuitive, input parameters, which not always have a clear, predictable effect on the output, the generated content.…”

“…We therefore believe that the integration of both procedural generation and manual editing operations is a very promising direction for this research. It seems to combine the best of two worlds, but so far the topic is as good as unaddressed, and it provides numerous new challenges to overcome (see [48]). For instance, manually rerouting a generated street through a city center might entail automatically moving and removing certain blocks of buildings and possibly creating new lots and individual buildings.…”

“…The solutions for this are detailed in [44]. Although improvements in hardware and new approaches such as gpu computing significantly alleviate the execution time of procedural methods, operations affecting large regions or requiring complex algorithms (e.g.…”

“…At the expense of some additional computation time, designers are provided with unlimited undo and redo facilities. Furthermore, because designers expect regenerated results to be exactly the same as before when redoing an action, we need to carefully manage the state of the random number generator used in procedural methods, as explained in [44].…”

The Effectiveness and Efficiency of Model Driven Game Design

“…Recent experiments with mixed initiative procedural content generation (PCG) [18,19] sketch the possibility of creating design tools that automate certain tasks to speed up the process of design. Procedural content generation is already being used in commercial games, in most cases to generate levels either during design time, or every time the player starts a new session.…”