23 research outputs found
Road surface 3D reconstruction based on dense subpixel disparity map estimation
Various 3D reconstruction methods have enabled civil engineers to detect
damage on a road surface. To achieve the millimetre accuracy required for road
condition assessment, a disparity map with subpixel resolution needs to be
used. However, none of the existing stereo matching algorithms are specially
suitable for the reconstruction of the road surface. Hence in this paper, we
propose a novel dense subpixel disparity estimation algorithm with high
computational efficiency and robustness. This is achieved by first transforming
the perspective view of the target frame into the reference view, which not
only increases the accuracy of the block matching for the road surface but also
improves the processing speed. The disparities are then estimated iteratively
using our previously published algorithm where the search range is propagated
from three estimated neighbouring disparities. Since the search range is
obtained from the previous iteration, errors may occur when the propagated
search range is not sufficient. Therefore, a correlation maxima verification is
performed to rectify this issue, and the subpixel resolution is achieved by
conducting a parabola interpolation enhancement. Furthermore, a novel disparity
global refinement approach developed from the Markov Random Fields and Fast
Bilateral Stereo is introduced to further improve the accuracy of the estimated
disparity map, where disparities are updated iteratively by minimising the
energy function that is related to their interpolated correlation polynomials.
The algorithm is implemented in C language with a near real-time performance.
The experimental results illustrate that the absolute error of the
reconstruction varies from 0.1 mm to 3 mm.Comment: 11 pages, 16 figures, IEEE Transactions on Image Processin
Road Crack Detection Using Deep Convolutional Neural Network and Adaptive Thresholding
Crack is one of the most common road distresses which may pose road safety
hazards. Generally, crack detection is performed by either certified inspectors
or structural engineers. This task is, however, time-consuming, subjective and
labor-intensive. In this paper, we propose a novel road crack detection
algorithm based on deep learning and adaptive image segmentation. Firstly, a
deep convolutional neural network is trained to determine whether an image
contains cracks or not. The images containing cracks are then smoothed using
bilateral filtering, which greatly minimizes the number of noisy pixels.
Finally, we utilize an adaptive thresholding method to extract the cracks from
road surface. The experimental results illustrate that our network can classify
images with an accuracy of 99.92%, and the cracks can be successfully extracted
from the images using our proposed thresholding algorithm.Comment: 6 pages, 8 figures, 2019 IEEE Intelligent Vehicles Symposiu
Multiple Lane Detection Algorithm Based on Optimised Dense Disparity Map Estimation
Lane detection is very important for self-driving vehicles. In recent years,
computer stereo vision has been prevalently used to enhance the accuracy of the
lane detection systems. This paper mainly presents a multiple lane detection
algorithm developed based on optimised dense disparity map estimation, where
the disparity information obtained at time t_{n} is utilised to optimise the
process of disparity estimation at time t_{n+1}. This is achieved by estimating
the road model at time t_{n} and then controlling the search range for the
disparity estimation at time t_{n+1}. The lanes are then detected using our
previously published algorithm, where the vanishing point information is used
to model the lanes. The experimental results illustrate that the runtime of the
disparity estimation is reduced by around 37% and the accuracy of the lane
detection is about 99%.Comment: 5 pages, 7 figures, IEEE International Conference on Imaging Systems
and Techniques (IST) 201
A Novel Disparity Transformation Algorithm for Road Segmentation
The disparity information provided by stereo cameras has enabled advanced
driver assistance systems to estimate road area more accurately and
effectively. In this paper, a novel disparity transformation algorithm is
proposed to extract road areas from dense disparity maps by making the
disparity value of the road pixels become similar. The transformation is
achieved using two parameters: roll angle and fitted disparity value with
respect to each row. To achieve a better processing efficiency, golden section
search and dynamic programming are utilised to estimate the roll angle and the
fitted disparity value, respectively. By performing a rotation around the
estimated roll angle, the disparity distribution of each row becomes very
compact. This further improves the accuracy of the road model estimation, as
demonstrated by the various experimental results in this paper. Finally, the
Otsu's thresholding method is applied to the transformed disparity map and the
roads can be accurately segmented at pixel level.Comment: 16 pages, 8 figure