Hoang Trinh

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Cashiers in retail stores usually exhibit certain repetitive and periodic activities when processing items. Detecting such activities plays a key role in most retail fraud detection systems. In this paper, we propose a highly efficient, effective and robust vision technique to detect checkout-related primitive activities, based on a hierarchical finite(More)
Substantial ambiguities arise in hand tracking due to issues such as small hand size, deformable hand shapes and similar hand appearances. These issues have greatly limited the capability of current multi-target tracking techniques in hand tracking. As an example, state-of-the-art approaches for people tracking handle indentity switching by exploiting the(More)
For safety purposes, railroad tracks need to be inspected on a regular basis for physical defects or design noncompliances. Such track defects and non-compliances, if not detected in a timely manner, may eventually lead to grave consequences such as train derailments. In this paper, we present a real-time automatic vision-based rail inspection system, with(More)
A variety of approaches using BP and image segmentation have been proposed for the stereo correspondence problem. In this paper, we introduce a novel approach, based on a combination of segmentation and BP. Our method inherits the idea of Multiscale BP, however at each level of the hierarchy, each graph node corresponds to an image segment, which we call(More)
In this paper, we present a real-time automatic vision-based rail inspection system, which performs inspections at 16 km/h with a frame rate of 20 fps. The system robustly detects important rail components such as ties, tie plates, and anchors, with high accuracy and efficiency. To achieve this goal, we first develop a set of image and video analytics and(More)
Humans, as well as many living organisms, are gifted with the power of Bseeing[ and Bunderstanding[ the environment around them using their eyes. The ease with which humans process and understand the visual world is very deceiving and often prompts us to underestimate the effort and methods needed to build practical, effective, and inexpensive computer(More)
We introduce a unified framework for scene structure and motion estimation on road-driving stereo sequences. This framework is based on the slanted-plane scene model that has become widely popular in the stereo vision community. Our algorithm iteratively and alternately solves for scene structure and motion. Surface estimation is done using our own(More)
In retail stores, cashier non-compliance activities at the Point of Sale (POS) are one of the prevalent sources of retail loss. In this paper, we propose a novel approach to reliably rank the list of detected non-compliance activities of a given retail surveillance system, thereby provide a means of significantly reducing the false alarms and improving the(More)
A major source of revenue shrink in retail stores is the intentional or unintentional failure of proper checking out of items by the cashier. More recently, a few automated surveillance systems have been developed to monitor cashier lanes and detect non-compliant activities such as fake item checkouts or scans done with the intention of deriving monetary(More)