Daniel J. Dailey

An algorithm to estimate mean traffic speed using uncalibrated cameras

We present a novel approach to estimate traffic speed using a sequence of images from an uncalibrated camera. We assert that exact calibration is not necessary to estimate speed. Instead, we use: 1) geometric relationships inherently available in the image, 2) some common-sense assumptions that reduce the problem to a one-dimensional geometry, 3) frame differencing to isolate moving edges and track vehicles between frames, and 4) parameters from the distribution of vehicle lengths to estimate speed.

Dynamic camera calibration of roadside traffic management cameras for vehicle speed estimation

In this paper, we present a new three-stage algorithm to calibrate roadside traffic management cameras and track vehicles to create a traffic speed sensor. The algorithm first estimates the camera position relative to the roadway using the motion and edges of the vehicles. Given the camera position, the algorithm then calibrates the camera by estimating the lane boundaries and the vanishing point of the lines along the roadway. The algorithm transforms the image coordinates from the vehicle tracker into real-world coordinates using our simplified camera model. We present results that demonstrate the ability of our algorithm to produce good estimates of the mean vehicle speed in a lane of traffic.

A novel technique to dynamically measure vehicle speed using uncalibrated roadway cameras

The Washington State Department of Transportation (WSDOT) has a network of several hundred CCTV traffic surveillance cameras deployed on the freeways and arterials around Seattle for congestion monitoring. However, these cameras are not calibrated and can be panned, tilted and zoomed. This paper presents a novel method of automatically computing enough calibration information for these cameras so that they can produce reliable speed estimates. The method presented uses a straightening technique to remove perspective effects and a correlation technique to establish the necessary scale factor. Temporal correlation between sequential straightened frames of video is used to make robust speed estimates.

Roadside camera motion detection for automated speed measurement

In this paper, we present an algorithm to detect scene change that indicates that camera re-calibration is necessary. This work is in support of using un-calibrated traffic management roadside cameras for automated speed estimates. We construct an activity region using moving vehicle edges, and small differences in the activity region in consecutive images are used as a decision criteria for recalibrating the camera. The camera motion detection uses training sets of 10-second video sequences and detects moving vehicles using frame differencing. We present a validation of our algorithm using real-world traffic scenes.

A method for GPS positioning

We present an algorithm that estimates position using the Global Positioning System (GPS) C/A code measurements. We include an approximation for the covariance of the position estimate.

An algorithm and implementation to predict the arrival of transit vehicles

This paper presents an algorithm to predict transit vehicle arrival times up to an hour in advance. The time series of data from an automated vehicle location system, consisting of time and location pairs, is used with historical statistics in an optimal filtering framework to predict future arrivals.

Neutronic response to two-phase flow in a nuclear reactor

Abstract The neutron noise induced by an air-water loop located in a nuclear reactor is investigated. A simple model of the neutron noise is developed using phenomenological arguments. The model is verified by comparison to experimental results, and three-dimensional, two-energy group diffusion calculations. The aim of the work is to provide the theoretical background for studying two-phase flow using neutron noise analysis.

Measurement of two phase flow properties using the nuclear reactor instrument

Abstract A procedure is introduced for characterizing one dimensional, two phase flow in terms of three properties; propagation, structure, and dynamics. It is shown that all of these properties can be measured by analyzing the response of the reactor neutron field to a two phase flow perturbation. Therefore, a nuclear reactor can be regarded as a two phase flow instrument.

Estimating Corridor Travel Time by Using Transit Vehicles as Probes

A corridor approach to travel-time estimates by using transit vehicles as probes is presented. These estimates increase the information density along the corridor, compared with use of only probe information at specified points. Speed estimates are provided that track the significant changes identified in inductance-loop data, but the estimate of the speed appears to be conservative. Comparison of instantaneous travel times, often used for real-time applications, and travel time computed by using a corridor speed surface indicates that the instantaneous travel times have a delay in tracking changes in the corridor and have higher maximum travel time.

Real-time bus information on mobile devices

We report on a real-time transit vehicle information system which delivers content to Internet-enabled mobile devices, such as cell phones. The content is in the form of predicted arrival/departure times for buses at user-selectable geographic locations within a transit region. We discuss how the physical restrictions of such devices, e.g., screen size and paucity of keyboard options, influences the user interface design. An overview of the system architecture is provided, together with some preliminary usage results.