Visual odometry is one of the key core technologies in the field of autonomous driving. However, images captured in lowlight or unevenly-illuminated scenes still cannot guarantee good performance due to low image contrast and lack of detail features. Therefore, we propose an end-to-end visual odometry method based on image fusion and FCNN-LSTM in the paper. The brightness image of the source image sequence is obtained by gray-scale transformation, and an image fusion algorithm based on spectral residual theory is designed to combine the image sequence and its brightness image to enhance the contrast of the image and provide more detailed information. In order to improve the accuracy of image feature extraction and reduce the error in the pose estimation process, we design a feature extraction algorithm based on skipfusion-FCNN. The traditional fully convolutional neural network (FCNN) is improved, a skip-fusion-FCNN network model is proposed, and three different paths are constructed for feature extraction. In each path, the prediction results of different depths are fused by downsampling to obtain a feature map. Merge three different feature maps to obtain feature fusion information, taking into account the structural information and detail information of the image. Experiments show that this algorithm is superior to the state-of-the-art algorithms.
LiDAR based Simultaneous Localization and Mapping (LiDAR SLAM) plays a vital role in autonomous driving and has attracted the attention of researchers. In order to achieve higher accuracy of motion estimation between adjacent LiDAR frames and reconstruction of the map, a segmentation-based LiDAR odometry and mapping framework is proposed in this paper. In detail, we first define the classification of several features with weak semantic information, the extraction method of which is achieved by a segmentation algorithm proposed in this paper that is based on greedy search. Based on the above work, a novel point cloud registration algorithm is also proposed in this paper, which is solved by modeling the problem as a nonlinear optimization problem. In order to verify the effectiveness of the proposed model, we collect a large amount of data in the autonomous driving test area to test it and compare the results with the existing state-of-the-art models. The experimental results show that the algorithm proposed in this paper can run stably in real-world autonomous driving scenarios and has smaller error and higher robustness compared with other models.
There is a growing concern about public security, especially the discovery of explosives hidden in mobile phones during security checks. However, there is almost no public dataset of explosive mobile phones to study this topic. We contribute the first explosive mobile phone benchmark dataset for security screening, named explosive mobile phones x-ray image dataset, which will be publicly available. Note that explosive mobile phone classification is a typical class imbalance task. Although the number of explosive mobile phones is far smaller than the number of normal mobile phones, one missed phone can cause a huge loss of life and property. To accurately identify explosives hidden in mobile phones, we propose a module called position information attention module (PIAM). Benefiting from aggregating the position information encoded in networks along the channel and spatial domains, PIAM highlights informative features of explosives. In addition, PIAM combines with other networks effectively at a low cost, empowering them with the ability to identify important details. Furthermore, in the face of the class imbalance, we propose a sample-oriented coefficient called sample cost with an update rule. Extensive experimental results show that PIAM and sample cost significantly improve the performance of many excellent networks in explosive mobile phone classification.
Evaluating the performance of image fusion algorithms objectively is still an open problem. We proposed an integrational approach to objective image fusion evaluation based on integrating different existing objective metrics in order to overcome their individual shortcomings. The process of the objective measure construction contains two steps: first, we construct a candidate measure set, where each element contains high evaluation accuracy and low correlation with each other; then, the weights of measures in constructing the target measure are determined dynamically on training image set. Considering that the true quality of fused images is a subjective perception, we introduce assessment indefiniteness when calculating the evaluation accuracy of each measure to reduce the influence of errors of subjective perception. Experiments on various images are conducted to test the effectiveness of the proposed measure. The results have shown that the measure is useful in conjunction with the other objective measures to account for qualitative subjective perception.
Multimodality image fusion provides more comprehensive information and has an increasingly wide range of uses. For the remote sensing image fusion, traditional multiresolution analysis (MRA)-based methods always have insufficiencies in contrast with spatial details. At the same time, traditional sum of modified Laplace may do blocking artifacts. In order to overcome these deficiencies, we propose a remote sensing image fusion method based on the mutual-structure for joint filtering and saliency detection. Our method uses joint filtering to facilitate the correct extraction of the high and low frequency from source images. The saliency detection method also improves the effect of low-frequency fusion, and the high-frequency sub-bands calculate the extended sum of modified Laplace for better fusion. The method is compared with other five classical fusion methods. The experimental results show that the algorithm effectively preserves the structural information and textural information of the image and improves the sharpness of the fused image. It turns out to have many advantages in subjective and objective evaluation.
In the case of poor lighting conditions, it is easy to capture the underexposed images with low contrast and low quality. Traditional single-image enhancement methods often fail in revealing image details because of the limited information in a single-source image. A single underexposed image enhancement method based on adaptive decomposition and convolutional neural network (CNN) is proposed. The CNN training models only need images with different brightness rather than a strict ground-truth image. First, a simple effective synchronous decomposition method is proposed to solve the synergy problem in multisource image decomposition. Then, two CNN models are designed for the high-frequency part and low-frequency part, respectively. They process the high-frequency and low-frequency sub-bands, instead of the entire source images. The weight map obtained from the CNN model represents the contrast distribution. The exposure map generated by gradient-based visibility assessment indicates the exposure distribution. Finally, the weight map and the exposure map are multiplied to generate the final decision map. Experimental results demonstrate that the proposed method outperforms competing methods.
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