CMRT09

Stilla, Uwe

Bibliographic data

Monograph

Persistent identifier:: 856955019

Author:: Stilla, Uwe

Title:: CMRT09

Sub title:: object extraction for 3D city models, road databases, and traffic monitoring ; concepts, algorithms and evaluation ; Paris, France, September 3 - 4, 2009 ; [joint conference of ISPRS working groups III/4 and III/5]

Scope:: X, 234 Seiten

Year of publication:: 2009

Place of publication:: Lemmer

Publisher of the original:: GITC

Identifier (digital):: 856955019

Illustration:: Illustrationen, Diagramme, Karten

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: GRAMMAR SUPPORTED FACADE RECONSTRUCTION FROM MOBILE LIDAR MAPPING Susanne Becker, Norbert Haala

Document type:: Monograph

Structure type:: Chapter

In: Stilla U, Rottensteiner F, Paparoditis N (Eds) CMRT09. IAPRS, Voi. XXXVIII, Part 3/W4 — Paris, France, 3-4 September, 2009 229 GRAMMAR SUPPORTED FACADE RECONSTRUCTION FROM MOBILE LIDAR MAPPING Susanne Becker, Norbert Haala Institute for Photogrammetry, University of Stuttgart Geschwister-Scholl-Straße 24D, D-70174 Stuttgart forename.lastname@ifp.uni-stuttgart.de KEY WORDS: Architecture, Point Cloud, Urban, LiDAR, Facade Interpretation ABSTRACT: The paper describes an approach for the quality dependent reconstruction of building facades using 3D point clouds from mobile terrestrial laser scanning and coarse building models. Due to changing viewing conditions such measurements frequently suffer from different point densities at the respective building facades. In order to support the automatic generation of facade structure in regions where no or only limited LiDAR measurements are available, a quality dependent processing is implemented. For this purpose, facades are reconstructed at areas of sufficient LiDAR point densities in a first processing step. Based on this reconstruction, rules are derived automatically, which together with the respective facade elements constitute a so-called facade grammar. This grammar holds all the information that is necessary to reconstruct facades in the style of the given building. Thus, it can be used as knowledge base in order to improve and complete facade reconstructions at areas of limited sensor data. Even for parts where no LiDAR measurements are available at all synthetic facade structures can be hypothesized providing detailed building geometry. 1. INTRODUCTION Due to the growing need for visualization and modelling of 3D urban landscapes numerous tools for the area covering production of virtual city models were made available, which are usually based on 3D measurements from airborne stereo imagery or LiDAR. This airborne data collection, which mainly provides the outline and roof shape of buildings, is frequently complemented by terrestrial laser scanning (TLS). However, the applicability of standard TLS is usually limited to the 3D data capturing of smaller scenes from a limited number of static viewpoints. In contrast, the application of dynamic TLS from moving platforms allows the complete coverage of spatially complex urban environments from multiple viewpoints. One example of such a mobile mapping system, which combines terrestrial laser scanners with suitable sensors for direct georeferencing, is the StreetMapper system (Kremer and Hunter, 2007). This system enables the rapid and area covering measurement of dense 3D point clouds by integrating four 2D laser scanners with a high performance GNSS/inertial navigation system. By these means accuracy levels better than 30mm have been demonstrated for point measurement in urban areas (Haala et al., 2008). In general, such systems allow for an efficient measurement of larger street sections including the facades of the neighbouring buildings. However, depending on the look angle during the scanning process, strong variations of the available point densities at the building facades can occur. Such viewpoint limitations and occlusions will subject the collected point cloud to significant changes of accuracy, coverage and amount of detail. For this reason, the following interpretation of the measured point clouds will be hampered by considerable changes in data quality. Thus, algorithms for automatic facade reconstruction have to be robust against potentially incomplete data sets of heterogeneous quality. For this purpose, dense point cloud measurements for facades with good visibility are used in our approach to extract rules on dominant or repetitive features as well as regularities. These rules then are used as knowledge base to generate facade structure for parts or buildings where no sensor data is available. By these means bottom-up and top- down propagation of knowledge can be combined in order to profit from both reconstruction techniques. The production rules, which are automatically inferred from well observed and modelled facades, are represented by a formal grammar. Such formal grammars are frequently used within knowledge based object reconstruction to ensure the plausibility and the topological correctness of the reconstructed object elements. Lindenmayer-systems (L-systems), which can be applied to model the growth processes of plants, are well known examples of formal grammars (Prusinkiewicz and Lindenmayer, 1990). So-called split grammars are introduced by Wonka et al. (2003) to automatically generate architectural structures from a database of rules and attributes. Similarly, Müller et al. (2006) present a procedural modelling approach for the generation of detailed building architecture in a predefined style. However, the variety of facade structures which can be generated is restricted to the knowledge base inherent in the grammar rules or model libraries. Thus, the appearance of facade elements is limited to prespecified types, even when leaving some freedom in the values of their parameters. Another problem while applying such approaches for object reconstruction is that manual interaction is required to constitute suitable building styles and translate them into some kind of model or grammar description. For this reason, several approaches aim at deriving such kind of knowledge from observed or given data. For example, Ripperda (2008) derives prior facade information from a set of facade images in order to support the stochastic modelling process. However, existing methods which try to derive procedural rules from given images as proposed by Müller et al. (2007) or Van Gool et al. (2007) still resort to semi-automatic methods. The same holds true for the work of Aliaga et al. (2007). They present an interactive system for both the creation of new buildings in the style of others and the modification of existing buildings. At first, the user manually subdivides a building into its basic external features. This segmentation is then employed to automatically infer a grammar

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