Stephan Heuel and Wolfgang Förstner and Felicitas Lang, "Topological and Geometrical Reasoning in 3D Grouping for Reconstructing Polyhedral Surfaces", In Proceedings of the 19th ISPRS Congress. Amsterdam, pp. 397-404, 3A. 2000.

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We are developing a system for reconstructing polyhedral surfaces from multiple images. This process can take advantage of the topological relations of the observed image features triggering and therefore speeding up the grouping of features to polyhedral surfaces. Exploiting the statistical properties of features when grouping them leads to consistent decisions being invariant to numbering and choice of coordinate system and allows statistical testing. This simplifies the choice of thresholds to the definition of a scene independent significance level. We decribe the topological and statistical models used within our system. Experiments with synthetic and real data prove the feasibility of the approach.

@inproceedings{Heuel2000Topological,
  author = {Heuel, Stephan and F\"orstner, Wolfgang and Lang, Felicitas},
  title = {Topological and Geometrical Reasoning in 3D Grouping for Reconstructing Polyhedral Surfaces},
  booktitle = {Proceedings of the 19th ISPRS Congress},
  year = {2000},
  pages = {397--404, 3A}
}

André Fischer and Thomas H. Kolbe and Felicitas Lang, "On the Use of Geometric and Semantic Models for Component-Based Building Reconstruction", In Semantic Modeling for the Acquisition of Topographic Information from Images and Maps, Smati '99 Workshop. Förstner, Wolfgang and Lidtke, C. -E. and Bückner J. (Eds.) Institut für Photogrammetrie, Universität Bonn, pp. 101-119. 1999.

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3D building data is needed in many application areas. Besides the geometric description an increasing number of applications also demand thematic information about acquired buildings. We present a concept for the automatic extraction of buildings from aerial images. In contrast to other approaches generic building structures both are geometrically reconstructed and semantically classified. A component-based, parameterized building model is employed to control the reconstruction of buildings. This paper describes how geometric and semantic knowledge of buildings is propagated through the different aggregation levels of the building model. Furthermore, it is shown how rules and constraints are derived from the model and exploited at each stage of the reconstruction process.

@inproceedings{Fischer1999Use,
  author = {Fischer, Andr\'e and Kolbe, Thomas H. and Lang, Felicitas},
  editor = {F\"orstner, Wolfgang and Lidtke, C. -E. and B\"uckner J.},
  title = {On the Use of Geometric and Semantic Models for Component-Based Building Reconstruction},
  booktitle = {Semantic Modeling for the Acquisition of Topographic Information from Images and Maps, Smati '99 Workshop},
  year = {1999},
  pages = {101--119}
}

Felicitas Lang, "Geometrische und semantische Rekonstruktion von Gebäuden durch Ableitung von 3D Gebäudeecken". Thesis at: Institute of Photogrammetry, University of Bonn. 1999.

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Summary
During the last years, three-dimensional building data have increasingly gained importance for practical applications as in architecture and planning. Aerial images are suitable for the photogrammetric reconstruction of buildings. This thesis makes a contribution to automatic building extraction from multiple overlapping images. The reconstruction comprises the extraction of the geometric as well as the semantic object description, i. e. the interpretation of the objects. The modeling of knowledge about the scene by means of object-, image- and sensor-modeling plays an important role in the extraction from image data. The complexity of the objects as well as their appearance in the images requires the use of a hierarchical building model that contains both a part-of and a specialization hierarchy. The part-of hierarchary comprises different levels of domain-specific aggregation and enables the access to the semantics of the objects by using the class-specific geometric and topologic properties of the objects and the connectivity relations between objects of different levels. The specific features of the procedure are the following:
- The use of a hierarchical building model with semantically motivated levels of the part-of and the specialization hierarchy for reconstruction of building components and for their aggregation in object space.
- The coherent modeling both in object and in image space. Starting from the image data the image model allows the access to 3d-components of the objects during the reconstruction. Starting from object components the object model allows the access to complex objects during the 3d-aggregation by using semantically related connectivity structures.
- The close interaction of geometric and semantic reconstruction that combines the mainly data driven construction of model instances and the model-driven verification exploiting the maximum available knowledge.
- Uncertainties are taken into account by statistically modeling the deviation between data and model.
The procedure allows the reconstruction and interpretation of complex buildings of variable geometry, topology and structure. The algorithm is demonstrated on different image material. It shows promising results, especially in suburban areas.
Zusammenfassung
In den letzten Jahren haben dreidimensionale Gebäudedaten für Anwendungen in Bereichen wie z. B. der Architektur und dem Planungswesen zunehmend an Bedeutung gewonnen. Luftbilder stellen eine geeignete Grundlage für die photogrammetrische Rekonstruktion der Gebäude dar. Diese Arbeit liefert einen Beitrag zur automatischen Gebäudeerfassung aus mehrfach überdeckten Bildszenen. Die Rekonstruktion beinhaltet dabei sowohl die Erfassung der geometrischen als auch der semantischen Beschreibung, d. h. die Interpretation der Objekte. Eine entscheidende Rolle bei der Erfassung aus Bilddaten spielt die Beschreibung des Wissens über die zu erfassende Szene in Form von Objekt-, Bild- und Sensormodellen. Die Komplexität der Objekte sowie deren Erscheinung in den Bildern erfordert die Verwendung eines hierarchischen Gebäudemodells, das sowohl eine Bestandteils- als auch eine Spezialisierungshierarchie beinhaltet. Die Bestandteilshierarchie umfaßt dabei unterschiedliche Ebenen objektspezifischer Aggregation und ermöglicht durch klassenspezifische geometrische und topologische Eigenschaften der Objekte sowie der Verknüpfungsrelationen der Objekte unterschiedlicher Ebenen, den Zugriff auf die Semantik der Objekte. Die Besonderheiten des vorgestellten Verfahrens sind:
- Die Nutzung eines hierarchischen Gebäudemodells mit semantisch motivierten Bestandteils- und Spezialisierungsebenen zur Rekonstruktion von Gebäudebestandteilen und deren Aggregierung im Objektraum.
- Die kohärente Modellierung im Objekt- und im Bildraum. Ausgehend von den Bilddaten ermöglichen bei der Rekonstruktion die Bildmodelle den Zugriff auf 3D-Objektkomponenten. Ausgehend von Objektkomponenten ermöglichen bei der Aggregierung die Objektmodelle den Zugriff auf komplexe Objekte durch semantisch motivierte Verknüpfungsstrukturen.
- Die enge Verkoppelung von geometrischer und semantischer Rekonstruktion durch den überwiegend datengetriebenen Aufbau von Modellinstanzen und die modellgetriebene Verifikation unter Nutzung des maximal verfügbaren Objektwissens.
- Die Berücksichtigung von Unsicherheiten durch statistische Modellierung der Abweichungen zwischen Daten und Modellen.
Die Vorgehensweise ermöglicht durch die Zerlegung in gebäudespezifische Bestandteile die Rekonstruktion und Interpretation komplexer Gebäude variabler Geometrie, Topologie und Struktur. Insgesamt zeigt die exemplarische Erprobung des Verfahrens an unterschiedlichem Bildmaterial insbesondere in Bereichen offener Bebauung vielversprechende Ergebnisse.

@phdthesis{Lang1999Geometrische,
  author = {Lang, Felicitas},
  title = {Geometrische und semantische Rekonstruktion von Geb\"auden durch Ableitung von 3D Geb\"audeecken},
  school = {Institute of Photogrammetry, University of Bonn},
  year = {1999}
}

Ansgar Brunn and Felicitas Lang and Eberhard Gülch and Wolfgang Förstner, "A Hybrid concept for 3D Building Acquisition", In Journal for Photogrammetry & Remote Sensing. Vol. 53, pp. 119-129. 1998.

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This paper presents a hybrid concept of interaction between scene and sensors for image interpretation. We present a strategy for 3D building acquisition which combines different approaches based on different levels of description and different sensors: the detection of regions of interest, and the automatic and semiautomatic reconstruction of object parts and complete buildings.

@inproceedings{Brunn1998Hybrid,
  author = {Brunn, Ansgar and Lang, Felicitas and G\"ulch, Eberhard and F\"orstner, Wolfgang},
  title = {A Hybrid concept for 3D Building Acquisition},
  booktitle = {Journal for Photogrammetry \& Remote Sensing},
  year = {1998},
  volume = {53},
  pages = {119--129},
  doi = {10.1016/S0924-2716(97)00039-7}
}

André Fischer and Thomas H. Kolbe and Felicitas Lang and Armin B. Cremers and Wolfgang Förstner and Lutz Plümer and Volker Steinhage, "Extracting Buildings from Aerial Images Using Hierarchical Aggregation in 2D and 3D", In Computer Vision and Image Understanding. 1998.

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We propose a model-based approach to automated 3D extraction of buildings from aerial images. We focus on a reconstruction strategy that is not restricted to a small class of buildings. Therefore, we employ a generic modeling approach which relies on the well-defined combination of building part models. Building parts are classified by their roof type. Starting from low-level image features we combine data-driven and model-driven processes within a multilevel aggregation hierarchy, thereby using a tight coupling of 2D image and 3D object modeling and processing, ending up in complex 3D building estimations of shape and location. Due to the explicit representation of well-defined processing states in terms of model-based 2D and 3D descriptions at all levels of modeling and data aggregation, our approach reveals a great potential for reliable building extraction.

@inproceedings{Fischer1998Extracting,
  author = {Fischer, Andr\'e and Kolbe, Thomas H. and Lang, Felicitas and Cremers, Armin B. and F\"orstner, Wolfgang and Pl\"umer, Lutz and Steinhage, Volker},
  title = {Extracting Buildings from Aerial Images Using Hierarchical Aggregation in 2D and 3D},
  booktitle = {Computer Vision and Image Understanding},
  year = {1998},
  doi = {10.1006/cviu.1998.0721}
}

André Fischer and Thomas H. Kolbe and Felicitas Lang, "Integration of 2D and 3D Reasoning for Building Reconstruction using a Generic Hierarchical Model", In Workshop on Semantic Modeling for the Acquisition of Topographic Information from Images and Maps SMATI. Bonn, Germany 1997.

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We propose a model-based approach to automated 3D extraction of buildings from aerial images. The semantics of the concept building is used to control and to evaluate building extraction in all stages of the process. It is encoded by means of generic 3D object modeling, which describes thematic and geometric constraints on the spatial appearences of buildings, and 2D image modeling, which integrates sensor and illumination modeling to describe the projective appearences of buildings, specific for the given aerial imagery. 3D object and 2D image modeling are tightly coupled within a multi-layered framework which reveals a is-part-of -hierachy of 3D building parts and their corresponding projective descriptions. The overall strategy follows the paradigm of hypotheses generation and verification and combines bottom-up (data-driven) and top-down (model-driven) processes. Due to the explicit representation of well defined processing states in terms of model-based 2D and 3D descriptions at all levels of modeling and data aggregation our approach reveals a great potential for a reliable building extraction.

@inproceedings{Fischer1997Integration,
  author = {Fischer, Andr\'e and Kolbe, Thomas H. and Lang, Felicitas},
  title = {Integration of 2D and 3D Reasoning for Building Reconstruction using a Generic Hierarchical Model},
  booktitle = {Workshop on Semantic Modeling for the Acquisition of Topographic Information from Images and Maps SMATI},
  year = {1997}
}

Felicitas Lang and Wolfgang Förstner, "Surface Reconstruction of Man-Made Objects using Polymorphic Mid-Level Features and Generic Scene Knowledge", Zeitschrift für Photogrammetrie und Fernerkundung. Vol. 6, pp. 193-202. 1996.

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This paper presents a new concept for 3D-surface reconstruction, which infers domain specific local 3D-structures in space from its observed local 2D-structures in multiple images using polymorphic relational image descriptions. A 3D-aggregation can combine these local 3D-structures and thus results in a 3D-boundary representation of man-made objects being useful for different analyses and simulations.

@article{Lang1996Surface,
  author = {Lang, Felicitas and F\"orstner, Wolfgang},
  title = {Surface Reconstruction of Man-Made Objects using Polymorphic Mid-Level Features and Generic Scene Knowledge},
  journal = {Zeitschrift f\"ur Photogrammetrie und Fernerkundung},
  year = {1996},
  volume = {6},
  pages = {193--202}
}

Ansgar Brunn and Felicitas Lang and G Eberhard and Wolfgang Förstner, "A Multi-Layer Strategy for 3D Building Acquisition", In Proceeding of IAPR-TC7 Workshop. Graz 1996.

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In various projects we investigate on the extraction of buildings on different type and representation of data. This paper presents a strategy for 3D building acquisition which combines different approaches based on different levels of description. The approach consists of detection of regions of interest and automatic and semiautomatic reconstruction of object parts and complete buildings. We incorporate the approach in a global concept of interaction between scene and sensors for image interpretation.

@inproceedings{Brunn1996Multi,
  author = {Brunn, Ansgar and Lang, Felicitas and G\ulch, Eberhard and F\"orstner, Wolfgang},
  title = {A Multi-Layer Strategy for 3D Building Acquisition},
  booktitle = {Proceeding of IAPR-TC7 Workshop},
  year = {1996}
}

Ansgar Brunn and Felicitas Lang and Wolfgang Förstner, "A Procedure for Segmenting Surfaces by Symbolic and Iconic Image Fusion", In Mustererkennung 96, Proceeding of the DAGM 96. Heidelberg, Germany, pp. 11-20. 1996.

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This paper deals with the derivation of a symbolic surface description exploiting the information of multiple images while using a minimum of domain knowledge. We present a new concept for segmenting surfaces by fusing multiple images both on the iconic and on the symbolic description level. In a first step a local 3D-reconstruction and interpretation is derived based on the result of a polymorphic feature extraction. It serves as prior information for a second step which refines the initial segmentation using the radiometric image content. Examples of the proposed procedure are presented for the application of 3D-building reconstruction from aerial images.

@inproceedings{Brunn1996Procedure,
  author = {Brunn, Ansgar and Lang, Felicitas and F\"orstner, Wolfgang},
  title = {A Procedure for Segmenting Surfaces by Symbolic and Iconic Image Fusion},
  booktitle = {Mustererkennung 96, Proceeding of the DAGM 96},
  year = {1996},
  pages = {11--20},
  doi = {10.1007/978-3-642-80294-2_2}
}

Felicitas Lang and Wolfgang Förstner, "3D-City Modeling with a Digital One-Eye Stereo System", In Proc. ISPRS Congress Comm. IV. Vienna 1996.

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3D-city information is crucial for a number of applications in city planning, environmental control or for telecommunication. We describe a semiautomatic system for acquiring the 3D-shape of buildings as topographic objects. Buildings are either modeled as a freely structured union of basic shape primitives or as prisms with an arbitrary ground plan, covering a large percentage of existing buildings. Interaction takes place in only one image, requiring the operator to specify the approximate structure and shape of the buildings. 3D-reconstruction including both, height determination and form adaptation, is performed automatically using various matching tools. The paper describes the features of the system and reports on its efficiency based on an extensive test.

@inproceedings{Lang19963D,
  author = {Lang, Felicitas and F\"orstner, Wolfgang},
  title = {3D-City Modeling with a Digital One-Eye Stereo System},
  booktitle = {Proc. ISPRS Congress Comm. IV},
  year = {1996}
}

Carola Braun and Thomas H. Kolbe and Felicitas Lang and Wolfgang Schickler and Volker Steinhage and Armin B. Cremers and Wolfgang Förstner and Lutz Plümer, "Models for Photogrammetric Building Reconstruction", In Computer und Graphics. Vol. 19, pp. 109-118. 1995.

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The paper discusses the modeling necessary for recovering man made objects - in this case buildings - in complex scenes from digital imagery. The approach addresses all levels of image analysis for deriving semantically meaningful descriptions of the scene from the image, via the geometrical/physical model of the objects and their counterparts in the image. The central link between raster image and scene are network-like organized aspects of parts of the objects. This is achieved by generically modelling the objects using parametrized volume primitives together with the application specific constraints, which seems to be adequate for many types of buildings. The paper sketches the various interrelationships between the different models and their use for feature extraction, hypothesis generation and verification.

@inproceedings{Braun1995Models,
  author = {Braun, Carola and Kolbe, Thomas H. and Lang, Felicitas and Schickler, Wolfgang and Steinhage, Volker and Cremers, Armin B. and F\"orstner, Wolfgang and Pl\"umer, Lutz},
  title = {Models for Photogrammetric Building Reconstruction},
  booktitle = {Computer und Graphics},
  year = {1995},
  volume = {19},
  pages = {109--118},
  doi = {10.1016/0097-8493(94)00126-J}
}

Felicitas Lang and Wolfgang Förstner, "Matching Techniques", In Proc.: 2nd Course in Digital Photogrammetry. 1995.

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One of the central tasks in Photogrammetry and Computer Vision is the localization and reconstruction of objects in the scene. Localization aims at determining the pose , i. e. the position and the orientation of an object. It assumes the form of the object to be known or at least to be known up to some structural or numerical parameters and the mutual relation between the reference frames, i. e. coordinate systems of the object and the cameras to be determined. Reconstruction , on the other hand aims at determining the form possibly also the structure of the object. The form description need not, but may be related to a e. g. object centred, reference coordinate system. In all cases the central tasks is to match the description of one or several images to the description of the images or objects, i.e. to establish correspondence. In all cases automating localization and reconstruction requires to establish the correspondence or match between several images or between one or several images and a model. We therefore may distinguish several cases: * Image Matching * Object Localization * Object Reconstruction which are discussed in this publication.

@inproceedings{Lang1995Matching,
  author = {Lang, Felicitas and F\"orstner, Wolfgang},
  title = {Matching Techniques},
  booktitle = {Proc.: 2nd Course in Digital Photogrammetry},
  year = {1995}
}

Felicitas Lang and Thomas Löcherbach and Wolfgang Schickler, "A one-eye Stereo System for Semi-Automatic 3D-Building Extraction", In Geomatics Info Magazine. 1995.

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We present a semi-automatic system for building extraction that has been developed at the Institute for Photogrammetry at the University of Bonn. Digitized images are used as data source. Data capture takes place at a simple workstation. Single point measurement is replaced by the measurement of building models. Automation supports the operator and thus increases the system performance. The representation of building models allows a link to CAD, GIS and computer graphics.

@inproceedings{Lang1995one,
  author = {Lang, Felicitas and L\"ocherbach, Thomas and Schickler, Wolfgang},
  title = {A one-eye Stereo System for Semi-Automatic 3D-Building Extraction},
  booktitle = {Geomatics Info Magazine},
  year = {1995}
}

Carola Braun and Thomas H. Kolbe and Felicitas Lang and Wolfgang Schickler and Volker Steinhage and Armin B. Cremers and Wolfgang Förstner and Lutz Plümer, "Models for Photogrammetric Building Reconstruction", In Computers & Graphics. 1994.

• Abstract
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The paper discusses the modeling necessary for recovering man made object - in this case buildings - in complex scenes from digital imagery. The approach addresses all levels of image analysis for deriving semantically meaningful descriptions of the scene from the image, via the geometrical / physical model of the objects and their counterparts in the image. The central link between raster image and scene are network-like organized aspects of parts of the objects. This is achieved by generically modelling the objects using parametrized volume primitives together with the application specific constraints, which seems to be adequate for many types of buildings. The paper sketches the various interrelationships between the different models and their use for feature extraction, hypothesis generation and verification.

@inproceedings{Braun1994Models,
  author = {Braun, Carola and Kolbe, Thomas H. and Lang, Felicitas and Schickler, Wolfgang and Steinhage, Volker and Cremers, Armin B. and F\"orstner, Wolfgang and Pl\"umer, Lutz},
  title = {Models for Photogrammetric Building Reconstruction},
  booktitle = {Computers \& Graphics},
  year = {1994},
  doi = {10.1016/0097-8493(94)00126-J}
}

Wolfgang Förstner and Felicitas Lang and Claudia Fuchs, "On the Noise and Scale Behaviour of Relational Descriptions", In ISPRS Commission III. 1994.

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The paper presents a concept for analysing the quality of relational descriptions of digital images. The investigations are based on the relational description automatically derived by a new coherent procedure for feature extraction providing a feature adjacency graph containing points, edges and segments and their relations. A new notion of scale (integration scale) is introduced, relating to a non linear function of the image, providing new stable descriptions. Based on the feature extraction we analysed the quality of the relational descriptions in dependency on the signal-to-noise ratio and on the control parameters of the feature extraction process, i.~e. the significance level, the smoothing scale and the integration scale. First results on the quality of the features, focussing on their existence, distinct attributes and relations are given. The scope of this research is to predict the quality, especially probabilities of components of the relational description from a few measures depending on noise, scale and local properties of the image content. This is motivated by the applications we are dealing with, namely extracting man-made 2D or 3D structures by grouping procedures or image matching as both tasks are optimization problems where the probability of the unknown 2D or 3D model has to be maximized. The paper presents a concept for analysing the quality of relational descriptions of digital images. The investigations are based on the relational description automatically derived by a new coherent procedure for feature extraction providing a feature adjacency graph containing points, edges and segments and their relations. A new notion of scale (integration scale) is introduced, relating to a non linear function of the image, providing new stable descriptions. Based on the feature extraction we analysed the quality of the relational descriptions in dependency on the signal-to-noise ratio and on the control parameters of the feature extraction process, i.~e. the significance level, the smoothing scale and the integration scale. First results on the quality of the features, focussing on their existence, distinct attributes and relations are given. The scope of this research is to predict the quality, especially probabilities of components of the relational description from a few measures depending on noise, scale and local properties of the image content. This is motivated by the applications we are dealing with, namely extracting man-made 2D or 3D structures by grouping procedures or image matching as both tasks are optimization problems where the probability of the unknown 2D or 3D model has to be maximized.

@inproceedings{Forstner1994Noise,
  author = {F\"orstner, Wolfgang and Lang, Felicitas and Fuchs, Claudia},
  title = {On the Noise and Scale Behaviour of Relational Descriptions},
  booktitle = {ISPRS Commission III},
  year = {1994}
}

Felicitas Lang and Wolfgang Schickler, "Semiautomatische 3D Gebäudeerfassung aus digitalen Bildern", Zeitschrift für Photogrammetrie und Fernerkundung.(5), pp. 193-200. 1993.

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The paper presents a concept for the model based threedimensional acquisition of buildings from single and multiple images. For solving the interpretation problem an automatic building extraction procedure requires an apropriate object model. We use parametrized models implicitely representing inherent geometric and topological contraints. The semiautomatic procedure supports the operator during the mensuration process and the final fit of the models to the image data. The implementation and first results are reported.

@article{Lang1993Semiautomatische,
  author = {Lang, Felicitas and Schickler, Wolfgang},
  title = {Semiautomatische 3D Geb\"audeerfassung aus digitalen Bildern},
  journal = {Zeitschrift f\"ur Photogrammetrie und Fernerkundung},
  year = {1993},
  number = {5},
  pages = {193--200}
}