Aiming to reduce pollutant emissions, bicycles are regaining popularity specially in urban areas. However, the number of cyclists' fatalities is not showing the same decreasing trend as the other traffic groups. Hence, monitoring cyclists' data appears as a keystone to foster urban cyclists' safety by helping urban planners to design safer cyclist routes. In this work, we propose a fully image-based framework to assess the rout risk from the cyclist perspective. From smartphone sequences of images, this generic framework is able to automatically identify events considering different risk criteria based on the cyclist's motion and object detection. Moreover, since it is entirely based on images, our method provides context on the situation and is independent from the expertise level of the cyclist. Additionally, we build on an existing platform and introduce several improvements on its mobile app to acquire smartphone sensor data, including video. From the inertial sensor data, we automatically detect the route segments performed by bicycle, applying behavior analysis techniques. We test our methods on real data, attaining very promising results in terms of risk classification, according to two different criteria, and behavior analysis accuracy.
Here we follow a different direction, taking advantage of the good properties yielded by using images as primary source of data. Indeed, computer vision techniques have been applied, for quite some time, to traditional cyclist monitoring tasks as volume counts @cite_33 and average speed, due to their reliability and efficiency when compared to manual methods @cite_31 . However, so far no work has addressed identification of dangerous situations using an on-board smartphone camera.
@cite_31 @cite_33
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One of the main challenges in the conduct of detailed analysis of cyclist behavior is the lack of reliable data. Collection of data through manual methods is a labor-intensive and time-consuming process. Two of the important areas of cyclist data collection are volume counts and average speed measurements. A volume count provides the basis for necessary exposure measures and conveys essential information about traffic patterns. Cyclist speed data are used for traffic control and safety studies. The application of computer vision (CV) techniques enables the collection of precise spatial and temporal measurements of road users in a resource-efficient way. This paper presents the use of a set of CV techniques for the automated collection of cyclist data. Cyclist tracks obtained from video analysis were used to perform screen line counts as well as cyclist speed measurements. The applications were demonstrated with the use of a real-world data set from a roundabout in Vancouver, British Columbia, Canada. Further analysis was conducted on the mean speed of cyclists with regard to several factors (e.g., travel path, helmet use, group size). The motivation for this research was to understand better cyclist behavior and how it varied under different conditions. Several conclusions could be drawn from the analysis of cyclist speed behavior. Group size, travel path, lane position, and helmet use were all found to affect the cyclist mean speed. Single cyclists had a slightly, but significantly, higher mean cycling speed than did group cyclists. The mean cycling speed was highest for those cyclists who used the road rather than the sidewalk. The mean cycling speed decreased for cyclists without helmets. It has great significance to acquire vehicle speed for active safety system. This paper presents a methodology for identifying vehicle speed by obtaining a sparse optical flow from image sequences. Distinct corners can be detected by Harris corner detector after image enhancement. Then, Lucas-Kanade method for optical flow calculation is utilized to match the sparse feature set of one frame on the consecutive frame. In order to improve the accuracy of optical flow, RANSAC algorithm is introduced to optimize the matched corners. Finally, the vehicle speed can be determined by averaging all the speeds estimated by every optimized matched corner. The results of field test indicated that the computation time of the developed method to execute for one time was 59ms, and the mean error of speed estimation relative to the measurement of GPS was 0.121 m s. The developed method can achieve satisfying performance, such as accuracy and output frequency. This paper introduces a dataset gathered entirely in urban scenarios with a car equipped with one stereo camera and five laser scanners, among other sensors. One distinctive feature of the present dataset is the existence of high-resolution stereo images grabbed at a high rate (20 fps) during a 36.8 km trajectory, which allows the benchmarking of a variety of computer vision techniques. We describe the sensors employed and highlight some applications which could be benchmarked using the present work. Both plain text and binary files are provided, as well as open-source tools for working with the binary versions. The dataset is available for download at http: www.mrpt.org MalagaUrbanDataset. In future, vehicles and other traffic participants will be interconnected and equipped with various types of sensors, allowing for cooperation on different levels, such as situation prediction or intention detection. In this article we present a cooperative approach for starting movement detection of cyclists using a boosted stacking ensemble approach realizing feature- and decision level cooperation. We introduce a novel method based on a 3D Convolutional Neural Network (CNN) to detect starting motions on image sequences by learning spatio-temporal features. The CNN is complemented by a smart device based starting movement detection originating from smart devices carried by the cyclist. Both model outputs are combined in a stacking ensemble approach using an extreme gradient boosting classifier resulting in a fast and yet robust cooperative starting movement detector. We evaluate our cooperative approach on real-world data originating from experiments with 49 test subjects consisting of 84 starting motions.