A structural approach for object detection and indoor localization with mobile devices

Author(s)

Henrique Morimitsu

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Matemática e Estatística (IME/SBI)
• Defense date: 2011-08-29

Examining board members

Roberto Marcondes Cesar Junior; Anna Helena Reali Costa; Roberto Hirata Junior

• Advisor: Roberto Marcondes Cesar Junior

Abstract

Object detection is an area of extreme importance for computer vision systems. Specially because of the increasing use of mobile devices, it becomes more and more important to develop methods and applications that can be used in such devices. In this sense, we propose the study and implementation of an application for mobile devices that is able to detect, in real time, existing indoor objects with an application to help a user in localization in the environment. The application depends solely on the device capabilities and hence, it is flexible and unconstrained. Object detection is accomplished by keygraph matching between images of previously chosen signs and the image currently being captured by the camera device. Keygraphs are a generalization of the traditional keypoints method and, by taking into consideration a set of points and its structural properties, are capable of describing the objects robustly and efficiently. In order to perform localization, we chose to detect signs existing in the environment. After each detection, we apply a simple, but very effective, localization method based on a comparison between the detected sign and a dataset of images of the whole environment. The dataset was built using several cameras atop a mobile structure, systematically capturing images of the environment at regular intervals. The implementation is described in details and we show results obtained from real tests in the chosen environment using a Nokia N900 cell phone. Such results are evaluated in terms of detection and localization estimation precision, as well as the elapsed time to perform the whole process. (AU)

• FAPESP's process: 09/04450-5 - Mobile Application for Helping Visually Impaired People in Text Identification
• Grantee: Henrique Morimitsu
• Support Opportunities: Scholarships in Brazil - Master