Unwritten Procedural Modeling with the Straight Skeleton

PhD Thesis (Glasgow, 2013)

Tom Kelly


Creating virtual models of urban environments is essential to a disparate range of applications, from geographic information systems to video games. However, the large scale of these environments ensures that manual modeling is an expensive option. Procedural modeling is a automatic alternative that is able to create large cityscapes rapidly, by specifying algorithms that generate streets and buildings. Existing procedural modeling systems rely heavily on programming or scripting – skills which many potential users do not possess. We therefore introduce novel user interface and geometric approaches, particularly generalisations of the straight skeleton, to allow urban procedural modeling without programming. We develop the theory behind the types of degeneracy in the straight skeleton, and introduce a new geometric building block, the mixed weighted straight skeleton. In addition we introduce a simplifcation of the skeleton event, the generalised intersection event. We demonstrate that these skeletons can be applied to two urban procedural modeling systems that do not require the user to write programs. The first application of the skeleton is to the subdivision of city blocks into parcels. We demonstrate how the skeleton can be used to create highly realistic city block subdivisions. The results are shown to be realistic for several measures when compared against the ground truth over several large data sets. The second application of the skeleton is the generation of building’s mass models. Inspired by architect’s use of plan and elevation drawings, we introduce a system that takes a floor plan and set of elevations and extrudes a solid architectural model. We evaluate the interactive and procedural elements of the user interface separately, finding that the system is able to procedurally generate large urban landscapes robustly, as well as model a wide variety of detailed structures.

latex src

Papers

T. Kelly, Unwritten procedural modeling with the straight skeleton, University of Glasgow, 2014.
Abstract | Bibtex | PDF
Creating virtual models of urban environments is essential to a disparate range of applications, from geographic information systems to video games. However, the large scale of these environments ensures that manual modeling is an expensive option. Procedural modeling is a automatic alternative that is able to create large cityscapes rapidly, by specifying algorithms that generate streets and buildings. Existing procedural modeling systems rely heavily on programming or scripting - skills which many potential users do not possess. We therefore introduce novel user interface and geometric approaches, particularly generalisations of the straight skeleton, to allow urban procedural modeling without programming. We develop the theory behind the types of degeneracy in the straight skeleton, and introduce a new geometric building block, the mixed weighted straight skeleton. In addition we introduce a simplifcation of the skeleton event, the generalised intersection event. We demonstrate that these skeletons can be applied to two urban procedural modeling systems that do not require the user to write programs. The first application of the skeleton is to the subdivision of city blocks into parcels. We demonstrate how the skeleton can be used to create highly realistic city block subdivisions. The results are shown to be realistic for several measures when compared against the ground truth over several large data sets. The second application of the skeleton is the generation of building's mass models. Inspired by architect's use of plan and elevation drawings, we introduce a system that takes a floor plan and set of elevations and extrudes a solid architectural model. We evaluate the interactive and procedural elements of the user interface separately, finding that the system is able to procedurally generate large urban landscapes robustly, as well as model a wide variety of detailed structures.
@unpublished{wrro146627,
editor = {R Poet and P Cockshott},
month = {February},
title = {Unwritten procedural modeling with the straight skeleton},
school = {ARRAY(0x7f690c285e98)},
author = {T Kelly},
publisher = {University of Glasgow},
year = {2014},
url = {http://eprints.whiterose.ac.uk/146627/},
abstract = {Creating virtual models of urban environments is essential to a disparate range of applications, from geographic information systems to video games. However, the large scale of these environments ensures that manual modeling is an expensive option. Procedural modeling is a automatic alternative that is able to create large cityscapes rapidly, by specifying algorithms that generate streets and buildings. Existing procedural modeling systems rely heavily on programming or scripting - skills which many potential users do not possess. We therefore introduce novel user interface and geometric approaches, particularly generalisations of the straight skeleton, to allow urban procedural modeling without programming.
We develop the theory behind the types of degeneracy in the straight skeleton, and introduce a new geometric building block, the mixed weighted straight skeleton. In addition we introduce a simplifcation of the skeleton event, the generalised intersection event. We demonstrate that these skeletons can be applied to two urban procedural modeling systems that do not require the user to write programs.
The first application of the skeleton is to the subdivision of city blocks into parcels. We demonstrate how the skeleton can be used to create highly realistic city block subdivisions. The results are shown to be realistic for several measures when compared against the ground truth over several large data sets.
The second application of the skeleton is the generation of building's mass models. Inspired by architect's use of plan and elevation drawings, we introduce a system that takes a floor plan and set of elevations and extrudes a solid architectural model. We evaluate the interactive and procedural elements of the user interface separately, finding that the system is able to procedurally generate large urban landscapes robustly, as well as model a wide variety of detailed structures.}
}
C. Vanegas, T. Kelly, B. Weber, J. Halatsch, D. Aliaga, and P. Müller, Procedural Generation of Parcels in Urban Modeling, Computer Graphics Forum, vol. 31, iss. 2pt3, p. 681–690, 2012.
Abstract | Bibtex | DOI | PDF
We present a method for interactive procedural generation of parcels within the urban modeling pipeline. Our approach performs a partitioning of the interior of city blocks using user?specified subdivision attributes and style parameters. Moreover, our method is both robust and persistent in the sense of being able to map individual parcels from before an edit operation to after an edit operation ? this enables transferring most, if not all, customizations despite small to large?scale interactive editing operations. The guidelines guarantee that the resulting subdivisions are functionally and geometrically plausible for subsequent building modeling and construction. Our results include visual and statistical comparisons that demonstrate how the parcel configurations created by our method can closely resemble those found in real?world cities of a large variety of styles. By directly addressing the block subdivision problem, we intend to increase the editability and realism of the urban modeling pipeline and to become a standard in parcel generation for future urban modeling methods.
@article{wrro138602,
volume = {31},
number = {2pt3},
month = {May},
author = {CA Vanegas and T Kelly and B Weber and J Halatsch and DG Aliaga and P M{\"u}ller},
note = {{\copyright} 2012 The Author(s) Computer Graphics Forum {\copyright} 2012 The Eurographics Association and Blackwell Publishing Ltd. This is the pre-peer reviewed version of the following article: Vanegas, CA, Kelly, T , Weber, B et al. (3 more authors) (2012) Procedural Generation of Parcels in Urban Modeling. Computer Graphics Forum, 31 (2). 2pt3. pp. 681-690, which has been published in final form at https://doi.org/10.1111/j.1467-8659.2012.03047.x. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.},
title = {Procedural Generation of Parcels in Urban Modeling},
publisher = {Wiley},
doi = {10.1111/j.1467-8659.2012.03047.x},
year = {2012},
journal = {Computer Graphics Forum},
pages = {681--690},
keywords = {I.3.5 [Computer Graphics]: Computational Geometry; I.3.6 [Computer Graphics]: Methodology and Techniques},
url = {http://eprints.whiterose.ac.uk/138602/},
abstract = {We present a method for interactive procedural generation of parcels within the urban modeling pipeline. Our approach performs a partitioning of the interior of city blocks using user?specified subdivision attributes and style parameters. Moreover, our method is both robust and persistent in the sense of being able to map individual parcels from before an edit operation to after an edit operation ? this enables transferring most, if not all, customizations despite small to large?scale interactive editing operations. The guidelines guarantee that the resulting subdivisions are functionally and geometrically plausible for subsequent building modeling and construction. Our results include visual and statistical comparisons that demonstrate how the parcel configurations created by our method can closely resemble those found in real?world cities of a large variety of styles. By directly addressing the block subdivision problem, we intend to increase the editability and realism of the urban modeling pipeline and to become a standard in parcel generation for future urban modeling methods.}
}
T. Kelly and P. Wonka, Interactive architectural modeling with procedural extrusions, ACM Transactions on Graphics, vol. 30, iss. 2, 2011.
Abstract | Bibtex | DOI | PDF
We present an interactive procedural modeling system for the exterior of architectural models. Our modeling system is based on procedural extrusions of building footprints. The main novelty of our work is that we can model difficult architectural surfaces in a procedural framework, e.g. curved roofs, overhanging roofs, dormer windows, interior dormer windows, roof constructions with vertical walls, buttresses, chimneys, bay windows, columns, pilasters, and alcoves. We present a user interface to interactively specify procedural extrusions, a sweep plane algorithm to compute a two-manifold architectural surface, and applications to architectural modeling.
@article{wrro138595,
volume = {30},
number = {2},
month = {April},
author = {T Kelly and P Wonka},
note = {(c) 2011, ACM. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in ACM Transactions on Graphics, Vol. 30, No. 2, Article 14, Publication date: April 2011.},
title = {Interactive architectural modeling with procedural extrusions},
publisher = {Association for Computing Machinery},
doi = {10.1145/1944846.1944854},
year = {2011},
journal = {ACM Transactions on Graphics},
keywords = {procedural modeling; roof modeling; urban modeling},
url = {http://eprints.whiterose.ac.uk/138595/},
abstract = {We present an interactive procedural modeling system for the exterior of architectural models. Our modeling system is based on procedural extrusions of building footprints. The main novelty of our work is that we can model difficult architectural surfaces in a procedural framework, e.g. curved roofs, overhanging roofs, dormer windows, interior dormer windows, roof constructions with vertical walls, buttresses, chimneys, bay windows, columns, pilasters, and alcoves. We present a user interface to interactively specify procedural extrusions, a sweep plane algorithm to compute a two-manifold architectural surface, and applications to architectural modeling.}
}

Authors from VCG

tom kelly