Realism in Data-Based Terrain Synthesis

Abstract

<p>The landscapes on Earth are varied and complex, having been created by innumerous physical processes over millions of years. The creation of artificial terrain that replicates the realism of landscapes on Earth has been a major challenge for computer graphics. Many different approaches have been taken, including approximating the terrain with fractals and splines, simulating the terrain using models from the physical geography, and reconstructing terrain from elements of real-world data. A primary issue in the field of terrain synthesis is the lack of, and evaluation of, realism in synthesized terrain. This thesis identifies and discusses the flaws of existing data-based methods based on example-based texture synthesis methods. It provides improvements to an existing data-based method using algorithms from the field of geographic information science, and presents a novel algorithm, ``terrain-optimization'', based on the example-based texture synthesis technique of texture-optimization. Finally, it discusses a new approach to the experimental evaluation of terrain realism, with the largest experiment conducted to date. The results of this show that each of the tested methods is indistinguishable from reality in certain circumstances and that those circumstances differ for each method tested, and that subjects with a high level of expertise in physical geography are the most qualified for identifying real terrain from synthesized terrain. Overall, the thesis provides substantial analysis and evidence about the challenges of data-based terrain synthesis while also developing new approaches in the field that perform as well as existing state-of-the-art methods.</p>

Example-based terrain synthesis with pit removal

“…There are three broad categories of terrain synthesis algorithms: procedural modelling, physically-based simulation, and example-based methods. These are covered in detail in Galin et al's 2019 review [4] and Scott's thesis [1].…”

“…Galin et al [4] and Scott [1] discuss the full range of example-based terrain synthesis methods. The three state-ofthe-art example-based terrain synthesis methods are those of Zhou et al [32], Tasse et al [33], and Gain et al [2].…”

“…Wei et al [39] classify texture synthesis into three main approaches: patch-based, pixel-based, and texture optimisation. The following summarises the three approaches and how they are applied to terrain synthesis; more detail is provided by Scott [1].…”

“…As part of this work, we also investigated a range of ways to adapt the method of texture optimisation to terrain generation. We report the best of our investigations here (the less successful methods are described in Scott's thesis [1]). The best algorithm, which incorporates pit removal, produces results that are different in character to other example-based approaches.…”

“…In addition, we summarise relevant prior work (Section 2), present example output, and summarise the results (Section 6) of a comparative study, that is reported fully elsewhere [1,3], comparing two state-of-the-art example based methods against our two algorithms that incorporate pit-removal.…”