970 research outputs found

    Product recognition in store shelves as a sub-graph isomorphism problem

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    The arrangement of products in store shelves is carefully planned to maximize sales and keep customers happy. However, verifying compliance of real shelves to the ideal layout is a costly task routinely performed by the store personnel. In this paper, we propose a computer vision pipeline to recognize products on shelves and verify compliance to the planned layout. We deploy local invariant features together with a novel formulation of the product recognition problem as a sub-graph isomorphism between the items appearing in the given image and the ideal layout. This allows for auto-localizing the given image within the aisle or store and improving recognition dramatically.Comment: Slightly extended version of the paper accepted at ICIAP 2017. More information @project_page --> http://vision.disi.unibo.it/index.php?option=com_content&view=article&id=111&catid=7

    Image Classification Using Bag-of-Visual-Words Model

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    Recently, with the explosive growth of digital technologies, there has been a rapid proliferation of the size of image collection. The technique of supervised image clas siļ¬cation has been widely applied in many domains in order to organize, search, and retrieve images. However, the traditional feature extraction approaches yield the poor classiļ¬cation accuracy. Therefore, the Bag-of-visual-words model, inspired by Bag-of Words model in document classiļ¬cation, was used to present images with the local descriptors for image classiļ¬cation, and also it performs well in some ļ¬elds. This research provides the empirical evidence to prove that the BoVW model outperforms the traditional feature extraction approaches for both binary image clas siļ¬cation and multi-class image classiļ¬cation. Furthermore, the research reveals that the size of the visual vocabulary during the process of building BoVW model impact on the accuracy results of image classiļ¬cation

    Object recognition for an autonomous wheelchair equipped with a RGB-D camera

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    This thesis has been carried out within a project at AR Lab (Autonomous Robot Laboratory) and IAS-Lab (Intelligent Autonomous Systems Lab) of Shanghai Jiao Tong University and University of Padua respectively. The project aims to create a system to recognize and localize multiple object classes for an autonomous wheelchair called JiaoLong, and in general for a mobile robot. The thesis had as main objective the creation of an object recognition and localization system in an indoor environment through a RGB-D sensor. The approach we followed is based on the recognition of the object by using 2D algorithm and 3D information to identify location and size of it. This will help to obtained robust performance for the recognition step and accurate estimation for the localization, thus changing the behavior of the robot in accordance with the class and the location of the object in the room. This thesis is mainly based on two aspects: ā€¢ the creation of a 2D module to recognize and detect the object in a RGB image; ā€¢ the creation of a 3D module to filter point cloud and estimate pose and size of the object. In this thesis we used the Bag of Features algorithm to perform the recognition of objects and a variation of the Constellation Method algorithm for the detection; 3D data are computed with several filtering algorithms which lead to a 3D analysis of the object, then are used the intrinsic information of point cloud for the pose and size estimation. We will also analyze the performance of the algorithm and propose some improvements aimed to increase the overall performance of the system besides research directions that this project could lea

    Modeling small objects under uncertainties : novel algorithms and applications.

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    Active Shape Models (ASM), Active Appearance Models (AAM) and Active Tensor Models (ATM) are common approaches to model elastic (deformable) objects. These models require an ensemble of shapes and textures, annotated by human experts, in order identify the model order and parameters. A candidate object may be represented by a weighted sum of basis generated by an optimization process. These methods have been very effective for modeling deformable objects in biomedical imaging, biometrics, computer vision and graphics. They have been tried mainly on objects with known features that are amenable to manual (expert) annotation. They have not been examined on objects with severe ambiguities to be uniquely characterized by experts. This dissertation presents a unified approach for modeling, detecting, segmenting and categorizing small objects under uncertainty, with focus on lung nodules that may appear in low dose CT (LDCT) scans of the human chest. The AAM, ASM and the ATM approaches are used for the first time on this application. A new formulation to object detection by template matching, as an energy optimization, is introduced. Nine similarity measures of matching have been quantitatively evaluated for detecting nodules less than 1 em in diameter. Statistical methods that combine intensity, shape and spatial interaction are examined for segmentation of small size objects. Extensions of the intensity model using the linear combination of Gaussians (LCG) approach are introduced, in order to estimate the number of modes in the LCG equation. The classical maximum a posteriori (MAP) segmentation approach has been adapted to handle segmentation of small size lung nodules that are randomly located in the lung tissue. A novel empirical approach has been devised to simultaneously detect and segment the lung nodules in LDCT scans. The level sets methods approach was also applied for lung nodule segmentation. A new formulation for the energy function controlling the level set propagation has been introduced taking into account the specific properties of the nodules. Finally, a novel approach for classification of the segmented nodules into categories has been introduced. Geometric object descriptors such as the SIFT, AS 1FT, SURF and LBP have been used for feature extraction and matching of small size lung nodules; the LBP has been found to be the most robust. Categorization implies classification of detected and segmented objects into classes or types. The object descriptors have been deployed in the detection step for false positive reduction, and in the categorization stage to assign a class and type for the nodules. The AAMI ASMI A TM models have been used for the categorization stage. The front-end processes of lung nodule modeling, detection, segmentation and classification/categorization are model-based and data-driven. This dissertation is the first attempt in the literature at creating an entirely model-based approach for lung nodule analysis

    Next Generation of Product Search and Discovery

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    Online shopping has become an important part of peopleā€™s daily life with the rapid development of e-commerce. In some domains such as books, electronics, and CD/DVDs, online shopping has surpassed or even replaced the traditional shopping method. Compared with traditional retailing, e-commerce is information intensive. One of the key factors to succeed in e-business is how to facilitate the consumersā€™ approaches to discover a product. Conventionally a product search engine based on a keyword search or category browser is provided to help users find the product information they need. The general goal of a product search system is to enable users to quickly locate information of interest and to minimize usersā€™ efforts in search and navigation. In this process human factors play a significant role. Finding product information could be a tricky task and may require an intelligent use of search engines, and a non-trivial navigation of multilayer categories. Searching for useful product information can be frustrating for many users, especially those inexperienced users. This dissertation focuses on developing a new visual product search system that effectively extracts the properties of unstructured products, and presents the possible items of attraction to users so that the users can quickly locate the ones they would be most likely interested in. We designed and developed a feature extraction algorithm that retains product color and local pattern features, and the experimental evaluation on the benchmark dataset demonstrated that it is robust against common geometric and photometric visual distortions. Besides, instead of ignoring product text information, we investigated and developed a ranking model learned via a unified probabilistic hypergraph that is capable of capturing correlations among product visual content and textual content. Moreover, we proposed and designed a fuzzy hierarchical co-clustering algorithm for the collaborative filtering product recommendation. Via this method, users can be automatically grouped into different interest communities based on their behaviors. Then, a customized recommendation can be performed according to these implicitly detected relations. In summary, the developed search system performs much better in a visual unstructured product search when compared with state-of-art approaches. With the comprehensive ranking scheme and the collaborative filtering recommendation module, the userā€™s overhead in locating the information of value is reduced, and the userā€™s experience of seeking for useful product information is optimized
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