Creation of procedural 3D building models can significantly lessen the costs of modeling, since it allows generating a variety of similar shapes from one procedural description. The common field of application for procedural modeling is modeling of straight building facades, which are very well suited for shape grammars – a special kind of procedural modeling system. In order to generate round building geometry, we present a way to setup different coordinate systems in shape grammars. Besides Cartesian, these are primarily cylindrical and spherical coordinate systems for generation of structures like towers or domes, that can procedurally adapt to different dimensions and parameters. The users can apply common splitting idioms from shape grammars in their familiar way, for creating round instead of straight geometry.

While the growing demand for new building models contained in virtual worlds, games, and movies, makes the easy and fast creation of modifiable models more and more important, 3D modeling of buildings can be a tedious task due to their sometimes complex geometry. For historic buildings, especially the roofs can be challenging. We present a new method of combining simple building solids to form more complex buildings, and give an emphasis on the blending of roof faces. This can be integrated in common pipelines for procedural modeling of buildings and will bring more expressiveness than existing methods.

With the current state of video games growing in scale, manual content creation may no longer be feasible in the future. Split grammars are a promising technology for large scale procedural generation of urban structures, which are very common in video games. Buildings with curved parts, however, can currently only be approximated by static pre-modeled assets, and rules apply only to planar surface parts. We present an extension to current split grammar systems that allows the generation of curved architecture through free-form deformations that can be introduced at any level in a grammar. Further subdivision rules can then adapt to these deformations to maintain length constraints, and repetitions can adjust to more or less space.

High-quality urban reconstruction requires more than multi-view reconstruction and local optimization. The structure of facades depends on the general layout, which has to be optimized globally. Shape grammars are an established method to express hierarchical spatial relationships, and are therefore suited as representing constraints for semantic facade interpretation. Usually inference uses numerical approximations, or hard-coded grammar schemes. Existing methods inspired by classical grammar parsing are not applicable on real-world images due to their prohibitively high complexity. This work provides feasible generic facade reconstruction by combining low-level classifiers with mid-level object detectors to infer an irregular lattice. The irregular lattice preserves the logical structure of the facade while reducing the search space to a manageable size. We introduce a novel method for handling symmetry and repetition within the generic grammar. We show competitive results on two datasets, namely the Paris 2010 and the Graz 50. The former includes only Hausmannian, while the latter includes Classicism, Biedermeier, Historicism, Art Nouveau and post-modern architectural styles.

Existing visual surveillance systems typically require that human operators observe video streams from different cameras, which becomes infeasible if the number of observed cameras is ever increasing. In this paper, we present a new surveillance system that combines automatic video analysis (i.e., single person tracking and crowd analysis) and interactive visualization. Our novel visualization takes advantage of a high resolution display and given 3D information to focus the operator's attention to interesting/ critical areas of the observed area. This is realized by embedding the results of automatic scene analysis techniques into the visualization. By providing different visualization modes, the user can easily switch between the different modes and can select the mode which provides most information. The system is demonstrated for a real setup on a university campus.

Gothic architecture, and especially window tracery, exhibits quite complex geometric shape configurations by combining only a few basic geometric patterns, namely circles and straight lines. They are combined using only a limited set of operations, such as intersection, offsetting, and extrusions. The reason lies in the process how these objects have been physically realized, i.e., through construction with compass and ruler. Consequently, Gothic architecture is a great, although challenging, domain for parametric modeling. We present some principles of this long-standing domain, together with some delicate details, and show how the constructions of some prototypic Gothic windows can be formalized using our Generative Modeling Language (GML). The emphasis of this procedural approach is on modularization, so that complex configurations can be obtained from combining elementary constructions. Different combinations of specific parametric features can be grouped together, which leads to the concept of styles. They permit to differentiate between the basic shape and its appearance, i.e., a particular ornamental decoration. This leads to an extremely compact representation for a whole class of shapes, which can nevertheless be quickly evaluated to obtain a connected manifold mesh of a particular window instance. The resulting mesh may also contain free-form surface parts, represented as subdivision surfaces.

The economic production and the interactive rendering of complete reconstructions of populated urban environments are technically difficult tasks. Specialized modelling tools, which exploit knowledge of the types of object being modelled by working in the application domain, can be used to create appealing virtual reconstructions quickly. At the same time, the structural information from the modeller gives valuable hints to the renderer to determine efficient interactive display strategies through the use of level-of-detail and culling techniques. Thus a modeller that knows the operator is creating houses can use this information to simplify the user interaction, guide the operator, and to create models that build in optimisations when attempting real-time rendering. In this paper we discuss the way in which polygonal and multi-resolution surface techniques can complement one another in the modelling of urban environments. We also draw more general conclusions which apply to other software systems that share the same objective.

Subdivision surfaces have become a standard technique for freeform shape modeling. They are intuitive to use and permit designers to flexibly add detail. But with larger control meshes, efficient adaptive rendering techniques are indispensable for interactive visualization and shape modeling. In this paper, we present a realization of tesselation‐on‐the‐fly for Loop subdivision surfaces as part of a framework for interactive visualization.