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:: ROAD ROUNDABOUT EXTRACTION FROM VERY HIGH RESOLUTION AERIAL IMAGERY M. Ravenbakhsh, C. S. Fraser

Document type:: Monograph

Structure type:: Chapter

ata with learners lham at an from ings of . Clas- , Mon- . Data rigs and lassifi- lensity- tabases ry and S. and tic ap- a. Pro- lm and edings artially trans- n Arti- Active 331. >f Fea- ng de metric 2006. Notes on for ars 24, rithms 37(3), msing metry ilding SPRS 9. Cooperative Research Center for Spatial Information, Department of Geomatics University of Melbourne VIC 3010, Australia [m.ravanbakhsh, c.fraser]@unimelb.edu.au KEY WORDS: roundabout detection, feature extraction, topographic database, high resolution imagery, snake model, level sets ABSTRACT: Road roundabouts, as a class of road junctions, are generally not explicitly modelled in existing road extraction approaches. This paper presents a new approach for the automatic extraction of roundabouts from aerial imagery through the use of prior knowledge from an existing topographic database. The proposed snake-based approach makes use of ziplock snakes. The external force of the ziplock snake, which is a combination of the Gradient Vector Flow force and the Balloon force, is modified based on the shape of the roundabout central island to enable the roundabout border to be delineated. Fixed boundary conditions for the proposed snake are provided by the existing road arms. A level set framework employing a hybrid evolution strategy is then exploited to extract the central island. Black-and-white aerial images of 0.1 m ground resolution taken over suburban and rural areas have been used in experimental tests which have demonstrated the validity of the proposed approach. 1. INTRODUCTION The need for accurate spatial databases and their automatic updating is increasing rapidly. Road networks form key information layers in topographic databases since they are used in such a wide variety of applications. As the extraction of roads from images is still generally manual, costly and time- consuming, there is a growing imperative to automate the process. However, such a feature extraction task has longed proved difficult to automate. The problem for automatic road extraction lies mostly in the complex content of aerial images. To ease the complexity of the image interpretation task, prior information can be used (Gerke, 2006; Boichis et al., 2000; Boichis et al., 1998; De Gunst, 1996). This often includes the provision of data from an external topographic database. Roundabouts, as a class of road junctions, are important components of a road network and if modelled well can improve the quality of road network extraction (Boichis et al., 1998). However, there are only few approaches which are dedicated to this task. Boichis et al. (2000) presented a knowledge based system for the extraction of road junctions and roundabouts. The method assumed that the description of simple road junctions and roundabouts is the same in the external database, so a previous detector has to certify the presence of the circular form. A parametric Hough Transform is used for this purpose. The roundabout is reconstructed after straight parts of the connecting roads, curved parts including splitter islands, and the circulating road are extracted. These elements are connected using geometric and radiometric continuities. In the approach, roads are treated as linear objects. Thus, elements such as the central island and the roundabout outline are not extracted, so kind of modelling does not always reflect the required degree of detail. In Fig. 1, vector data is superimposed on sample images to illustrate the problem. The image resolution is such that the roundabout’s central area covers the central island and the circulating roadway. In Fig. lb, the roundabout is represented as point object neglecting the central island and the circulating roadway. Thus, a detailed modelling of roundabouts is needed for data acquisition purposes at large scales. The detailed modelling of road roundabouts area objects is discussed in this paper, and an approach for their automatic extraction is proposed. This uses an existing topographic database leading to the extraction of refined roundabout data. In the following section, a model for roundabouts is first introduced. The stages of the proposed strategy are then illustrated in Sect. 3. Results from the implementation of the proposed approach using aerial imagery of 0.1 m ground resolution are presented and discussed in Sect. 4, together with an evaluation of their quality. Finally concluding remarks are offered. Figure 1. Superimposition of vector data on high resolution aerial images of road roundabouts. 2. ROUNDABOUT MODEL Illustrated in Fig. 2a is the conceptual two-part model of a roundabout, the parts being the roundabout itself and the road arms. The roundabout, where road arms are connected, is in turn composed of the roundabout border and its central area where a central island is located. A road arm is a rectilinear object which is represented as a ribbon with a constant width and two parallel road edges. Disturbances such as occlusions and shadows are not explicitly included in the model.

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