Chengcui Zhang

A progressive morphological filter for removing nonground measurements from airborne LIDAR data

Recent advances in airborne light detection and ranging (LIDAR) technology allow rapid and inexpensive measurements of topography over large areas. This technology is becoming a primary method for generating high-resolution digital terrain models (DTMs) that are essential to numerous applications such as flood modeling and landslide prediction. Airborne LIDAR systems usually return a three-dimensional cloud of point measurements from reflective objects scanned by the laser beneath the flight path. In order to generate a DTM, measurements from nonground features such as buildings, vehicles, and vegetation have to be classified and removed. In this paper, a progressive morphological filter was developed to detect nonground LIDAR measurements. By gradually increasing the window size of the filter and using elevation difference thresholds, the measurements of vehicles, vegetation, and buildings are removed, while ground data are preserved. Datasets from mountainous and flat urbanized areas were selected to test the progressive morphological filter. The results show that the filter can remove most of the nonground points effectively.

A decision tree-based multimodal data mining framework for soccer goal detection

We propose a new multimedia data mining framework for the extraction of soccer goal events in soccer videos by using combined multimodal analysis and decision tree logic. The extracted events can be used to index the soccer videos. We first adopt an advanced video shot detection method to produce shot boundaries and some important visual features. Then, the visual/audio features are extracted for each shot at different granularities. This rich multimodal feature set is filtered by a pre-filtering step to clean the noise as well as to reduce the irrelevant data. A decision tree model is built upon the cleaned data set and is used to classify the goal shots. Finally, the experimental results demonstrate the effectiveness of our framework for soccer goal extraction.

Learning-based spatio-temporal vehicle tracking and indexing for transportation multimedia database systems

One key technology of intelligent transportation systems is the use of advanced sensor systems for on-line surveillance to gather detailed information on traffic conditions. Traffic video analysis can provide a wide range of useful information to traffic planners. In this context, the object-level indexing of video data can enable vehicle classification, traffic flow analysis, incident detection and analysis at intersections, vehicle tracking for traffic operations, and update of design warrants. In this paper, a learning-based automatic framework is proposed to support the multimedia data indexing and querying of spatio-temporal relationships of vehicle objects in a traffic video sequence. The spatio-temporal relationships of vehicle objects are captured via the proposed unsupervised image/video segmentation method and object tracking algorithm, and modeled using a multimedia augmented transition network model and multimedia input strings. An efficient and effective background learning and subtraction technique is employed to eliminate the complex background details in the traffic video frames. It substantially enhances the efficiency of the segmentation process and the accuracy of the segmentation results to enable more accurate video indexing and annotation. The paper uses four real-life traffic video sequences from several road intersections under different weather conditions in the study experiments. The results show that the proposed framework is effective in automating data collection and access for complex traffic situations.

Video scene change detection method using unsupervised segmentation and object tracking

In order to manage the growing amount of video information efficiently, a video scene change detection method is necessary. Many advanced video applications such as video on demand (VOD) and digital library also require the scene change detection to organize the video content. In this paper, we present an effective scene change detection method using an unsupervised segmentation algorithm and the technique of object tracking based on the results of the segmentation. Our results have shown that this method can perform not only accurate scene change detection, but also obtain object level information of the video frames, which is very useful for video content indexing and analysis.

A multimodal data mining framework for soccer goal detection based on decision tree logic

In this paper, we propose a new multimedia data mining framework for the extraction of soccer goal events in soccer videos by utilising both multimodal analysis and decision tree logic. The extracted events can be used to index the soccer videos. We first adopt an advanced video shot detection method to produce shot boundaries and some important visual features. Then, the visual/audio features are extracted for each shot at different granularities. This rich multimodal feature set is then filtered by a pre-filtering step in order to clean the noise as well as to reduce the irrelevant data. A decision tree model is built upon the cleaned data set and is used to classify the goal shots. We also present the experimental results for the proposed framework, which indicate the performance of the framework for soccer goal extraction.

Adaptive background learning for vehicle detection and spatio-temporal tracking

Traffic video analysis can provide a wide range of useful information such as vehicle identification, traffic flow, to traffic planners. In this paper, a framework is proposed to analyze the traffic video sequence using unsupervised vehicle detection and spatio-temporal tracking that includes an image/video segmentation method, a background learning/subtraction method and an object tracking algorithm. A real-life traffic video sequence from a road intersection is used in our study and the experimental results show that our proposed unsupervised framework is effective in vehicle tracking for complex traffic situations.

A Multiple Instance Learning Approach for Content Based Image Retrieval Using One-Class Support Vector Machine

Multiple Instance Learning (MIL) is a special kind of supervised learning problem that has been studied actively in recent years. In this paper, we propose an approach based on One-Class Support Vector Machine (SVM) to solve MIL problem in the region-based Content Based Image Retrieval (CBIR). Relevance Feedback technique is incorporated to provide progressive guidance to the learning process. Performance is evaluated and the effectiveness of our retrieval algorithm has been shown through comparative studies.

A fast parallel modularity optimization algorithm (FPMQA) for community detection in online social network

As information technology has advanced, people are turning more frequently to electronic media for communication, and social relationships are increasingly found in online channels. Discovering the latent communities therein is a useful way to better understand the properties of a virtual social network. Traditional community-detection tasks only consider the structural characteristics of a social organization, but more information about nodes and edges such as semantic information cannot be exploited. What is more, the typical size of virtual spaces is now counted in millions, if not billions, of nodes and edges, most existing algorithms are incapable to analyze such large scale dense networks. In this paper, we first introduce an interesting social network model (Interest Network) in which links between two IDs are built if they both participate to the discussions about one or more topics/stories. In this case, we say both of the connected two IDs have the similar interests. Then, the edges of the initial network are updated using the attitude consistency information of the connected ID pairs. For a given ID pair i and j, they may together reply to some topics/IDs. The implicit orientations/attitudes of these two IDs to their together-reply topics/IDs may not be the same. We use a simple statistical method to calculate the attitude consistency, the value of which is between 0 and 1, and the higher value corresponds to a greater degree of consistency of the given ID pair to topics/IDs. The updated network is called Similar-View Network (SVN). In the second part, a fast parallel modularity optimization algorithm (FPMQA) that performs the analogous greedy optimization as CNM and FUC is used to conduct community discovering. By using the parallel manner and sophisticated data structures, its running time is essentially fast, O(k^m^a^x(k^m^a^x+logk^m^a^x)). Finally, we propose an evaluation metric, which is based on the reliable ground truths, for online network community detection. In the experimental work, we evaluate our method using real datasets and compare our approach with several previous methods; the results show that our method is more effective and accurate in find potential online communities.

A PCA-Based Vehicle Classification Framework

Due to its great practical importance, Intelligent Transportation System has been an active research area in recent years. In this paper, we present a framework that incorporates various aspects of an intelligent transportation system with its ultimate goal being vehicle classification. Given a traffic video sequence, the proposed system first proceeds to segment individual vehicles. Then the extracted vehicle objects are normalized so that all vehicles are aligned along the same direction and measured at the same scale. Following the preprocessing step, two classification algorithms - Eigenvehicle and PCA-SVM, are proposed and implemented to classify vehicle objects into trucks, passenger cars, vans, and pick-ups. These two methods exploit the distinguishing power of Principal Component Analysis (PCA) at different granularities with different learning mechanisms. Experiments are conducted to compare these two methods and the results demonstrate the effectiveness of the proposed framework.

A unified framework for image database clustering and content-based retrieval

With the proliferation of image data, the need to search and retrieve images efficiently and accurately from a large image database or a collection of image databases has drastically increased. To address such a demand, a unified framework called <i>Markov Model Mediators</i> (MMMs) is proposed in this paper to facilitate conceptual database clustering and to improve the query processing performance by analyzing the summarized knowledge. The unique characteristics of MMMs are that it provides the capabilities of exploring the affinity relations among the images at the database level and among the databases at the cluster level respectively, using an effective data mining process. At the database level, each database is modeled by an intra-database MMM which enables accurate image retrieval within the database. Then the conceptual database clustering is performed and cluster-level knowledge summarization is conducted to reduce the cost of retrieving images across the databases. This framework has been tested using a set of image databases, which contain various numbers of images with different dimensions and concept categories. The experimental results demonstrate that our framework achieves better retrieval accuracy via inter-cluster retrieval than that of intra-cluster retrieval with minimal extra effort.