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

In. Stilla U, Rottensteiner F, Paparoditis N (Eds) CMRT09. IAPRS, Vol. XXXVIII, Part 3/W4 — Paris, France, 3-4 September, 2009 An extracted road border is assumed to be correct if the maximum distance between the extracted road border and its corresponding reference does not exceed the buffer width. ijÜÜi % (a) (b) M H (c) (d) Figure 11. Capture of roundabout outline: (a) initial snakes in black and road arms in white, (b) and (c) evolving curves, and (d) reconstructed roundabout. Figure 12. Sample roundabout extraction results for scenes with varying degrees of complexity including disturbances. A smaller value of the buffer width can be chosen for an application that requires more accurate extraction results. A reference road border is assumed to be matched if the maximum deviation from the extracted object is within the buffer width. Based on these assumptions, three quality measures were adopted, the first being completeness, which is the ratio of the number of matched reference road borders to the number of reference objects. The second is correctness, which is the ratio of the number of correctly extracted road borders to the number of extracted objects, while the third is geometric accuracy, which is expressed by the average distance between the correctly extracted road border and the corresponding reference border, expressed as a Root Mean Square (RMS) value falling within the range of [0, buffer width]. Road border extraction results computed with different buffer width values are shown in Table 1. The completeness of the road border extraction increased as the buffer width value increased from 0.5m to 3m, implying that the results are more complete for higher buffer width values. The geometric accuracy increase is inversely proportional to buffer width so that results obtained with a value of 0.5m are more accurate than those obtained with a larger buffer width. For the buffer width value 0.5 m, the completeness is rather low. The reason is that a slight deviation of the extraction results from the true boundaries exceeding the buffer width frequently occurs due to disturbances and sometimes also due to road markings. Buffer width (m) 0.5 1 2 3 Number of road borders 41 41 41 41 Completeness 53% 62% 74% 85% Geometric accuracy (m) 0.30 0.38 0.50 0.58 Table 1. Evaluation results for road borders. As seen in Table 2, a favourable evaluation result was achieved in the extraction of central islands, which proved the robustness of the proposed method. Central islands of roundabouts were extracted with high values for completeness and correctness for the buffer width of 0.5m, implying the effectiveness of the proposed hybrid evolution strategy. For the buffer width value 1 m, all of central islands were extracted correctly. Buffer width (m) 0.5 1 Number of central islands 10 10 Completeness 90% 100% Correctness 90% 100% Geometric accuracy (m) 0.26 0.35 Table 2. Evaluation results for central islands. 5. CONCLUDING REMARKS A new snake-based approach to automatic extraction of road roundabouts has been described and analysed. Under the approach, the snake’s external force field is modified based on the shape of the central island to delineate the roundabout border. The modified snake force field can overcome various disturbances inside and outside the central island. It was shown that the use of prior-knowledge derived from an existing topographic database can considerably enhance the extraction performance. Furthermore, a level set approach with a hybrid evolution strategy was proposed to extract central islands. This produced good results in all 10 test cases, as central islands were extracted correctly for an assigned buffer width of lm. Nevertheless, partial occlusion of the central island border by large trees and shadowing cannot be overcome at this stage (Fig. 13). There are several possibilities to further enhance the results obtained so far and to be able to deal with more complex scenes. The incorporation of high-level prior knowledge about

Access restriction

Copyright

fullscreen: CMRT09

Monograph

Chapter

Table of contents

Cite and reuse

Monograph

Chapter

Image

Image fragment

Citation links

Citation recommendation