Publications

City sketching. James Gain, Patrick Marais and Rudolph Neeser. 2014. WSCG 2014: 22nd International Conference on Computer Graphics, Visualization and Computer Vision. 1-10. Download

Abstract: Procedural methods offer an automated means of generating complex cityscapes, incorporating the placement of park areas and the layout of roads, plots and buildings. Unfortunately, existing interfaces to procedural city systems tend to either focus on a single aspect of city layout (such as the road network) ignoring interaction with other elements (such as building dimensions) or expect numeric input with little visual feedback, short of the completed city, which may take up to several minutes to generate. In this paper we present an interface to procedural city generation, which, through a combination of sketching and gestural input, enables users to specify different land usage (parkland, commercial, residential and industrial), and control the geometric attributes of roads, plots and buildings. Importantly, the inter-relationship of these elements is pre-visualized so that their impact on the final city layout can be predicted. Once generated, further editing, for instance shaping the city skyline or redrawing individual roads, is supported. In general, City Sketching provides a powerful and intuitive interface for designing complex urban layouts.

Automatic addition of physics components to procedural content. Richard Baxter, Zacharia Crumley, Rudolph Neeser, James Gain. 2010. AFRIGRAPH ’10: Proceedings of the 7th International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa. 101-110. Doi: 10.1145/1811158.1811175

Abstract: While the field of procedural content generation is growing, there has been somewhat less work on developing procedural methods to animate these models. We present a technique for generating procedural models of trees and buildings via formal grammars (L-Systems and wall grammars) that are ready to be animated using physical simulation. The grammars and their interpretations are augmented to provide direct control over the physical animation, by, for example, specifying object mass and the joint stiffness. Example animations produced by our system include trees swaying in a gentle wind or being rocked by a gale, and buildings collapsing, imploding or exploding. In user testing, we had test subjects (n = 20) compare our animations with video of trees and buildings undergoing similar effects, as well as with animations in games that they have played. Results show that our animations appear physically accurate with a few minor instances of unrealistic behaviour. Users considered the animations to be more realistic than those used in current video games.

Comparing the accuracy and precision of three techniques used for estimating missing landmarks when reconstructing fossil hominin crania. Rudolph Neeser, Rebecca Rogers Ackermann, James Gain. 2009. American Journal of Physical Anthropology. 140:1-18. Doi: 10.1002/ajpa.21023

Abstract: Various methodological approaches have been used for reconstructing fossil hominin remains in order to increase sample sizes and to better understand morphological variation. Among these, morphometric quantitative techniques for reconstruction are increasingly common. Here we compare the accuracy of three approaches – mean substitution, thin plate splines, and multiple linear regression – for estimating missing landmarks of damaged fossil specimens. Comparisons are made varying the number of missing landmarks, sample sizes, and the reference species of the population used to perform the estimation. The testing is performed on landmark data from individuals of Homo sapiens, Pan troglodytes and Gorilla gorilla, and nine hominin fossil specimens. Results suggest that when a small, same-species fossil reference sample is available to guide reconstructions, thin plate spline approaches perform best. However, if no such sample is available (or if the species of the damaged individual is uncertain), estimates of missing morphology based on a single individual (or even a small sample) of close taxonomic affinity are less accurate than those based on a large sample of individuals drawn from more distantly related extant populations using a technique (such as a regression method) able to leverage the information (e.g., variation/covariation patterning) contained in this large sample. Thin plate splines also show an unexpectedly large amount of error in estimating landmarks, especially over large areas. Recommendations are made for estimating missing landmarks under various scenarios.

Laser Scanning for Conservation and Research of African Cultural Heritage Sites: The Case Study of Wonderwerk Cave, South Africa.. Rüther H., Chazan M., Schroeder R., Neeser R., Held C., Walker S.J., Matmon A., Horwitz L.K.. 2009. Journal of Archaeological Science. 36:1847-1856. Doi: 10.1016/j.jas.2009.04.012

Abstract: The ‘African Cultural Heritage and Landscape Database’ project, initiated and directed by the senior author and administered by Aluka (www.aluka.org), is aimed at the creation of a digital library of spatial and non-spatial materials relating to cultural heritage sites in Africa. The archaeological site of Wonderwerk Cave (South Africa) is one of 19 sites documented to date using laser scanning, conventional survey, digital photogrammetry and 3D modelling. To date, it is one of the few archaeological caves worldwide to be fully scanned. This paper explores the different uses to which the spatial data derived from this cave have been, or will be, put – for historical and educational purposes, scientific research and site conservation and development.