Adrian Iftene, Jean Vanderdonckt (Eds.) 113 Terrain Synthesis from Crude Heightmaps Alexandre Philippe Mangra Technical University of Cluj- Napoca Str. G. Barițiu 28, 400027, Cluj-Napoca, România alexandre.mangra@gmail.com Adrian Sabou Technical University of Cluj- Napoca Str. G. Barițiu 28, 400027, Cluj-Napoca, România adrian.sabou@cs.utcluj.ro Dorian Gorgan Technical University of Cluj- Napoca Str. G. Barițiu 28, 400027, Cluj-Napoca, România dorian.gorgan@cs.utcluj.ro ABSTRACT This paper presents an approach to terrain synthesis from minimal-detail user-provided heightmaps. There is no assumption regarding the level of detail provided, in order to allow users without access to powerful heightmap tools and/or resources to generate useable terrain based on a self-provided crude feature plan. We present the issues stemming from a lack of detail in user input, notably sharp altitude increases and oversimplified feature edges, and proceed to elaborate on using the terrain synthesis algorithm to solve the issues and create a level of detail that more closely resembles realistic terrain models. The algorithm pipeline is presented and parametrized to show how the user can influence the resulting model. Author Keywords Terrain synthesis; Heightmap; Worley noise; Perlin noise; Filters. ACM Classification Keywords H.5.m. Information interfaces and presentation (e.g., HCI): Miscellaneous. General Terms Algorithms; Terrain models. INTRODUCTION Over the past decades, computational power has become less expensive and more powerful thanks to technological advances. Alongside it, computer generated imagery (CGI) increased in availability and potential. CGI is one of the mainstays of technology, used in various fields like video games, movies, art, simulation software and anywhere else image generation is beneficial. One of the reasons for its popularity is the artistic freedom it entails, coupled with the potential to mimic something that does not exist in the real world. When compared to physical props and background, computer generated imagery becomes evidently advantageous. There is a large number of images unable to be accurately reproduced without the use of computers, be it spaceships, hellish creatures, otherworldly plants or simply vast, expanding landscapes. Creating a quality physical replica would incur costs unreasonable for any budget, not to mention unfeasible if we’re considering the entire landscape of an alien planet. A virtual reproduction’s costs can easily be quantified in the artist’s and/or programmer’s work and the required hardware. Thus, the industry’s needs have fueled the development of an array of algorithms and generation software tailored specifically at creating this kind of models. Among them, terrain generation is one of the most used fields due to it contributing significantly at reducing production costs of backgrounds. The terrain model can be created procedurally (using a set of rules) or based on a set of given input data. The latter is usually combined further with algorithms to refine the given data and produce something usable. Purely procedural terrain suffers from restricting the user control over the final location of terrain features like mountains, hills, plains, rivers or islands. On the other side of the spectrum, some synthesis algorithms working with input data such as heightmaps, feature graphs or guides require at least part of the data to be highly specific. This can prove inconvenient to the casual user, forcing him to spend increasing amounts of time researching the software used and finding ways of creating the necessary input. The casual user, then, raises new issues when trying to create terrain with specific features. He will, in most cases, be unable to properly form input data relevant for the application that would lead up to the desired terrain model. It can become tedious and time-consuming to master a new skill or software in order to obtain decent results. One issue will be the sudden altitude increases caused by the user creating the input heightmap by hand. Painting the heightmap with only a handful of colors or grayscale values leads to the creation of a layered terrain which does not conform to reality nor has any kind of transition between layers, hence the sharp, perfectly vertical, altitude changes. Another issue is the lack of detail on such models. The layman will have neither the time nor experience to paint “rough” edges, as seen in nature at the delimitation of two differently elevated areas. There is a high probability of encountering very uniform edges, if not downright straight, thus breaking the illusion of natural, chaotic, form. This paper elaborates on a simple algorithm which tries to solve these issues by detailing very crude input to a point where it becomes usable, either as the final terrain model or as a more precise input heightmap for more complex algorithms.