| Author | Marikhu, Ramesh |
| Call Number | AIT Thesis no.ICT-07-11 |
| Subject(s) | Remote-sensing images
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| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Information and Communications Technologies, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. ICT-07-11 |
| Abstract | The roads from satellite images are extracted using Euclidean invariant a priori information in the form of linear and quadratic geometric energy functionals for the higher order active contours. The segmentation process is done using the Quadratic Snakes. A quadratic energy functional is defined for the snake and the minimization of the energy is implemented using gradient descent method after the complex energy functional is solved for Euler Lagrange equations. Higher Order Active Contours have been found effective to model a more sophisticated geometric information. The finger-like structures that are created using quadratic geometric energy proves to be a good model for finding linear networks. This thesis is focused on the use of the quadratic energy functionals proposed by Rochery et al. (2003), the GVF energy proposed by Xu and Prince (1997) and the oriented filtering (Rochery et al., 2005) for robust extraction of road networks. I have developed an application for complete road extraction process to analyze the evolution of a family of quadratic snakes. The system allows easy tuning of the parameters and provides display of the various energies for comprehensive understanding of the evolution process. The system is designed for training the parameters that the snake depends on by considering each extraction process as a project. The process of extraction of roads from images can be automatic if the parameters that are dependent on the image characteristics are known in advance. The initialization of quadratic snakes is automated by using a rounded rectangle (Rochery et al., 2003) in which case the snake should shrink and snap to the edges of the roads when in equilibrium. Proper analysis of the evolution of the quadratic snake and the influence of numerous parameters and weights that it depends on, would allow extracting complex objects with high precision and recall. The pre-processing, extraction and post-processing activities would be specific to the problem of interest and the required type of results. In order to ensure that the approach is rotation and translation invariant, all the energy functionals used need to be Euclidean invariant to enable the extraction process to be independent of initialization. Experiments have been performed to analyze the influence of parameters of quadratic snake on the evolution of the original active contour into finger-like structures. Experiments have also been conducted to check the effectiveness of the quadratic snakes with the quadratic energies coupled with GVF and the image energy obtained by using filters for the detection of local lines. The oriented filtering requires user interaction for obtaining effective values for the parameters. Several other parameters are obtained empirically |
| Year | 2007 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. ICT-07-11 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Information and Communication Technology (ICT) |
| Chairperson(s) | Dailey, Matthew N; |
| Examination Committee(s) | Honda, Kiyoshi;Makhanov, Stanislav S; |
| Scholarship Donor(s) | High Level Commission for Information Technology (HLCIT), Nepal;Asian Institute of Technology Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2007 |