Road detection based on superpixels and anisotropic heat diffusion

Multi-scale local feature detection enables downstream registration and recognition tasks in medical image analysis. This paper articulates a novel robust method for multi-scale local feature extraction on volumetric data. The central idea is the elegant unification of local/global eigen-structures within the powerful framework of anisotropic heat diffusion. First, the local vector field is constructed by way of Hessian matrix and its eigenvectors/eigenvalues. Second, anisotropic heat kernels are computed using the vector field’s global graph Laplacian. Robust local features are manifested as extrema across multiple time scales, serving as volumetric heat kernel signature. To tackle the computational challenge for massive volumetric data, we propose a multiresolution strategy for hierarchical feature extraction based on our feature-preserving down-sampling approach. As a result, heat kernels and local feature identification can be approximated at a coarser level first, and then are pinpointed in a localized region at a finer resolution. Another novelty of this work lies at the initial heat design directly using local eigenvalue for anisotropic heat diffusion across the volumetric domain. We conduct experiments on various medical datasets, and draw comparisons with 3D SIFT method. The diffusion property of our local features, which can be interpreted as random walks in statistics, makes our method robust to noise, and gives rise to intrinsic multi-scale characteristics.

There are problems needed to be solved when extracting centerline of structured light strip on multi-pass seam. The problems include complex shape, non-uniform intensity distribution, disconnected caused by welding beans or occlusion and environmental noise etc. To solve these problems, a novel centerline extraction algorithm is proposed based on anisotropic heat diffusion. Putting pixels gray values as the temperature, the algorithm could get centerline composed by highest energy pixels, through heat diffusion along same temperature curve normal directions. The higher accuracy and efficiency of our algorithm is proved by experiments.

Multi-scale geometric processing has been a popular and powerful tool in graphics, which typically employs isotropic diffusion across scales. This paper proposes a novel method of multi-scale anisotropic heat diffusion on manifold, based on the new normal-driven shape representation and Edge-weighted Heat Kernels (EHK). The new shape representation, named as Normal-Controlled Coordinates (NCC), can encode local geometric details of a vertex along its normal direction and rapidly reconstruct surface geometry. Moreover, the inner product of NCC and its corresponding vertex normal, called Normal Signature (NS), defines a scalar/heat field over curved surface. The anisotropic heat diffusion is conducted using the weighted heat kernel convolution governed by local geometry. The convolution is computed iteratively based on the semigroup property of heat kernels toward accelerated performance. This diffusion is an efficient multi-scale procedure that rigorously conserves the total heat. We apply our new method to multi-scale feature detection, scalar field smoothing and mesh denoising, and hierarchical shape decomposition. We conduct various experiments to demonstrate the effectiveness of our method. Our method can be generalized to handle any scalar field defined over manifold.

For surveillance robots, road detection is of high importance for other functionalities such as pedestrian detection, obstacle avoidance, autonomous running, etc. The vision-based road detection is to classify image pixels belonging to road surface or not. Up to now, most algorithms are designed for working during daytime. In this paper, we focus on road detection at night. Firstly a planar reflection model is used to fit the intensity distribution of the images pixels got from a near-infrared camera. After that, we use a pixel-based classification to determine whether the pixel belongs to the road surface or not. In the experiments, we compare our algorithm with the region growing method. The results show that our approach works better in several aspects.

In this paper, an intelligent and automatic moving object edge detection algorithm is proposed, based on heat flow analogy. This algorithm starts with anisotropic heat diffusion in the spatial domain to remove noise and sharpen region boundaries for the purpose of obtaining high quality edge data. Then, isotropic heat diffusion is applied in the temporal domain to calculate the total amount of heat flow. The moving edges are represented as the total amount of heat flow out from the reference frame. The overall process is completed by non-maxima suppression and hysteresis thresholding to obtain binary moving edges. Evaluation results indicate that this approach has advantages in handling noise in the temporal domain because of the averaging inherent of isotropic heat flow. Results also show that this technique can detect moving edges in image sequences.

Pattern forming instabilities of the nematic smectic-B interface

Image transform, which transforms one image to another image by co-ordinate transformation, is often conducted in remote sensing applications. Image transform methods include forward mapping and reverse mapping. In this paper we propose a new forward image mapping method. Since a grid pixel in the source image may be no longer mapped to a grid pixel in the target image, gap phenomenon, i.e. some grids in the target may not receive information from any source pixel, occurs via forward mapping. Our method fills the gaps with information surrounding them using the image inpainting technique. Imagine that the image is a temperature field, i.e. the pixel value is the temperature value. The heat will transfer to the gaps, thus the gaps are filled after some time. This can be achieved by solving the classical diffusion equation. Furthermore, if the features in the image are rather complicated, we can use anisotropic heat diffusion (total variation diffusion) to fill the gaps in order to well preserve the edge features. The experimental result demonstrates the effectiveness of the proposed inpainting method.

In this paper, we propose the dense disparity map-based pedestrian detection method for intelligent vehicle. The dense disparity map is utilized to improve the pedestrian detection performance. Our method consists of several steps namely, obstacle area detection using road feature information and column detection, pedestrian area detection using dense disparity map-based segmentation, and pedestrian detection using optimal feature. The first step is to detect all obstacle areas using column detection and pedestrian height information. However, there are many objects in single obstacle area. Thus each obstacle area needs to be separated into single object for improving pedestrian detection performance. Thus, the second step is performed to segment the detected obstacle area. The last step is to detect only pedestrian using classifier trained by optimal feature. The optimal feature is extracted by positive and negative training images. ETH database is utilized to evaluate our proposed pedestrian detection method.

Road detection is a vital task for the development of autonomous vehicles. The knowledge of the free road surface ahead of the target vehicle can be used for autonomous driving, road departure warning, as well as to support advanced driver assistance systems like vehicle or pedestrian detection. Using vision to detect the road has several advantages in front of other sensors: richness of features, easy integration, low cost or low power consumption. Common vision-based road detection approaches use low-level features (such as color or texture) as visual cues to group pixels exhibiting similar properties. However, it is difficult to foresee a perfect clustering algorithm since roads are in outdoor scenarios being imaged from a mobile platform. In this paper, we propose a novel high-level approach to vision-based road detection based on geographical information. The key idea of the algorithm is exploiting geographical information to provide a rough detection of the road. Then, this segmentation is refined at low-level using color information to provide the final result. The results presented show the validity of our approach.

Road detection is important in computer vision for autonomous driving, pedestrian detection and other applications. Visible light (VL) camera is often used for daytime road detection, and infrared camera is often used for night road detection. Vanishing point (VP) detection is useful for inferring road region. Many VP detection methods have been proposed and applied successfully in VL road image. However, there is no special VP detection method for infrared road image. In this paper, we propose a VP detection approach for infrared road detection. The novelty of our approach relies on the rational assumption that the regions are very similar along the direction of the true VP. This assumption is involved in finding effective VP voters by using a non-local similarity manner, and these VP voters estimate the VP together. Quantitative and qualitative experiments show the effectiveness and efficiency of the proposed method.KeywordsVanishing point detectionInfrared Road detectionNon-local similarity

Illumination, for pedestrian detection at nighttime is weak, and detection is easily affected through variations in illumination. Thus, a bicharacteristic method of pedestrian detection at nighttime based on hierarchical tree cascade classification is presented according to “coarse-to-fine” principle. The proposed method consists of two stages of cascade classifiers. Coarse cascade classifiers are constructed in complete binary tree architecture. These classifiers use Haar-like features for the rapid identification of candidate pedestrian areas. By contrast, fine cascade classifiers have a parallel structure. Edgelet features are used for detection along three parts: the head-shoulder, trunk, and leg parts of candidate pedestrian areas. Bayesian decision-making is adopted to achieve pedestrian target detection and a comprehensive analysis of the detection results from these three parts. Experiments show that the proposed method has high accuracy, ideal real-time performance, and strong reliability...

Road detection aims at detecting the (drivable) road surface ahead vehicle and plays a crucial role in driver assistance system. To improve the accuracy and robustness of road detection approaches in complex environments, a new road detection method based on CNN (convolutional neural network) and MRF (markov random field) is proposed. The original road image is segmented into super-pixels of uniform size using simple linear iterative clustering (SLIC) algorithm. On this basis, we train the CNN which can automatically learn the features that are most beneficial to classification. Then, the trained CNN is applied to classify road region and non-road region. Finally, based on the relationship between the super-pixels neighborhood, we utilize MRF to optimize the classification results of CNN. Quantitative and qualitative experiments on the publicly datasets demonstrate that the proposed method is robust in complex environments. Furthermore, compared with state-of-the-art algorithms, the approach provides the better performance.

Vision-based automatic detection and tracking of on-road vehicles is a demanding research area in intelligent transportation systems (ITS). Several investigation reports are available in the literature in this research field using various machine learning (ML) techniques. This article proposes a method for on-road vehicle detection and tracking in varying weather conditions by modifying the structure of you only look once (YOLO), a recently developed deep learning model in computer vision for detecting objects. ML-based systems repurpose classifiers to detect the vehicles, whereas in YOLO model, a single convolutional neural network (CNN) predicts the detecting bounding boxes and the class probabilities for those boxes together in one evaluation from the full images. As the entire detection is performed using a single network, the detection process can be viewed as an end-to-end system. In this work, 16 convolutional layers of YOLO have been used along with two fully connected layers at the end. The vehicles have been detected in varying weather conditions. Two different public data sets, namely CDNet 2014 and LISA 2010 data sets have been used to evaluate the system performance, and it outperforms state-of-the-art results.

Automatic road identification and labeling in Landsat 4 TM images

Vehicle detection from very-high-resolution satellite imagery has received increasing interest during the last few years. In this article, we propose an automatic system for operational traffic monitoring using very-high-resolution optical satellite imagery (0.5–0.6 m resolution) of small highways with low traffic density and a range of different illumination conditions, including cloud-shadowed, hazy, and partially cloudy conditions. The proposed system includes cloud and cloud shadow detection, road detection, and vehicle detection, classification, and counting. The main part of the system is vehicle detection, which is constructed using an elliptical blob detection strategy followed by region growing and feature extraction steps. Vehicular objects are separated from non-vehicular objects using a K-nearest-neighbour classifier, with various classical features used for pattern recognition, as well as some proposed application-specific features, and are also classified according to vehicle size. The fully automatic processing chain has been validated on a selection of satellite scenes from different parts of Norway, including imagery with large amounts of cloud, fog, cloud shadows, and similar conditions that complicate image interpretation. The overall vehicle detection rate was 85.4% and the false detection rate was 9.2%. Overall, this demonstrates the potential of operational traffic monitoring using very-high-resolution satellites.