Weiguo Gong

Wavelet-Based Pavement Distress Image Edge Detection with à Trous Algorithm

Edge detection is an alternative method in the process for identifying and classifying pavement cracks for automated pavement evaluation systems. A number of edge detectors are widely used in image processing; most specify only a spatial scale for detecting edges. However, pavement surface images frequently have various details at different scales. Therefore, wavelet-based multiscale technique can be a candidate to extract edge information from pavement surface images. Instead of detecting edges in the space domain, wavelet analysis has the ability to describe both domains in time and in frequency. It was first applied in image edge detection in 1992, using the local maximum of the magnitude of the gradient to obtain edge representation. Nevertheless, this subsampling algorithm leads to a loss of translation variance and may produce many artifacts. In this paper, wavelet edge detection based on à trous algorithm (holes algorithm) is used in pavement distress segmentation. This algorithm is an undecimated wavelet transform executed via a filter bank without subsampling process. Translation invariance is one of its most important advantages. Therefore, the algorithm can minimize the artifact in the denoised data. Results of experiments on images are discussed in the paper. By comparisons with the results derived from five other traditional edge detectors, the study demonstrates the validity and effectiveness of this method for edge detection of pavement surface distresses.

Automated Road Sign Inventory System Based on Stereo Vision and Tracking

Detection, recognition, and positioning of road signs are critical components of a roadway asset management system. In this research, a stereo vision- based system is developed to conduct automated road sign inventory. The system in real time integrates and synchronizes the data streams from multiple sensors of high-resolution cameras, Differential Global Position- ing System receivers, Distance Measurement Instrument, and Inertial Measurement Unit. Algorithms are devel- oped based on data sets from the multiple positioning sensors to determine the positions of the moving vehi- cle and the orientation of the cameras. The key findings from the research include feature extraction and analysis that are applied for automated sign detection and recog- nition in the Right-of-Way (ROW) images, implementing a tracking algorithm of the candidate sign region among the image frames so the same signs are not counted more than once in an image sequence, and implementing stereo vision technique to compute the world coordinates of the road sign from the stereo-paired ROW images. Particu- lar techniques are employed to conduct all data acquisi- tion and analysis in real time onboard the vehicle. This system is an advanced alternative to traditional inventory methods in terms of safety and efficiency.

DATA ANALYSIS OF REAL-TIME SYSTEM FOR AUTOMATED DISTRESS SURVEY

Accurate data collection and interpretation of pavement data are critical for the decision-making process in pavement management. This study focused on the data analysis portion of a new automated system capable of collecting and analyzing pavement surface distress, mainly cracks, in real time through the use of a high-resolution digital camera; efficient image processing algorithms; and multicomputer, multi-CPU-based parallel computing. Features and performance of the automated system for distress survey were surveyed. Three protocols of producing distress indices incorporated into the automated system were examined: the AASHTO interim distress protocol, the World Bank’s Universal Cracking Indicator, and the Texas Department of Transportation’s method. It was found that distress results from the automated system were consistent for multiple passes of the same pavement sections.

Database Support for the New Mechanistic-Empirical Pavement Design Guide

The proposed Mechanistic-Empirical Pavement Design Guide (MEPDG) developed under the NCHRP Project 1-37A initiative is a significant advancement in pavement design. However, it is substantially more complex than the 1993 AASHTO design guide and it requires significantly more input from the designer. Some of the required data either are not available or are stored in locations not familiar to designers. In addition, many data sets need to be preprocessed for use in MEPDG. Thus, there was a need to study the data requirements for MEPDG and produce a centralized database system to aid designers. This paper describes the development of a comprehensive database that can be used to store and process climate, traffic, material, and performance data for the state of Arkansas. The tasks undertaken were to (a) identify all the necessary input and analysis parameters required, (b) develop the database structures for uploading the required data, (c) locate the available data sets and begin populating the database, and (d) develop a data interface to the MEPDG software. The completed database will improve the management and accessibility of the MEPDG input data, and its completion is a critical step before the calibration and implementation of MEPDG.

Real-time automated survey of pavement surface distress

Accurate data collection and interpretation of pavement data is critical for the decisionmaking process in pavement management. Collection of several data types for pavement management is automated and widely used. However, collection and analysis of pavement surface distress is still a manual process for many highway agencies, even though substantial amount of resources were used in the past decades to devise automated approaches for collecting and analyzing pavement surface distress. This paper introduces a new automated system capable of collecting and analyzing pavement surface distress, primarily cracks, in real-time through the use of high resolution digital camera, efficient image processing algorithms and multi-computer, and multi-CPU based parallel computing. The paper overviews the major steps in the algorithms for image processing. It is shown in the paper that distress results from the automated system are consistent for multiple passes of the same pavement sections.

Kalman Filter-Based Tracking System for Automated Inventory of Roadway Signs

Roadway signs represent a substantial investment of public money in road and highway infrastructure. However, the current level of automation in sign identification and recognition, size dimensioning, and location identification is unsatisfactory. In an effort to improve the automation level of sign inventory, feature extraction and Kalman filter-based tracking techniques for road signs in right-of-way (ROW) images are developed. A framework that combines the conventional image-processing methods with the Kalman filter tracking method is applied to improve the accuracy and efficiency of ROW image processing. With this tracking technique, the candidate region of the road sign in an image can be predicted on the basis of the image in the previous frame. With image processing used near the candidate region of a sign, detection efficiency and accuracy can be improved. The methodologies described fit a dynamic and moving environment, appropriate for a highway survey vehicle.

Automated Tracking System for Inventory of Roadway Signs

Roadway signs represent a substantial investment of public money in road and highway infrastructure. However, the current level of automation in sigh identification and recognition, size dimensioning, and location identification is not satisfactory. This paper targets the development of an automated road inventory system that addresses these issues. A framework of combining the conventional image processing methods with the Kalman filter tracking method is applied to improve the accuracy and efficiency of the ROW image processing. Through the tracking technique, the candidate region of the road sign in the picture can be predicted based on the previous image frame. Detection efficiency and accuracy of the sign can be improved. The methodologies described in the paper fit a dynamic and motion environment, appropriate for a highway survey vehicle.