Infrastructure maintenance of complex environments like railroads is a very expensive operation. Recent advances in mobile mapping systems to collect 3D point cloud data and in deep learning for detection and segmentation can prove to be very helpful in automating this maintenance and allowing preventive maintenance at certain locations before big failures occur. Some fully-supervised methods have been developed for understanding dynamic railroad environments. These methods often fail to generalize to infrastructure changes or new classes in low-labeled data. To address this issue, we propose a railroad segmentation method that leverages few-shot learning by generating class prototypes for the most relevant infrastructure classes. This method takes advantage of existing embedding networks for point clouds, taking the geometrical and spatial context into account for feature representation of complex connected classes. We evaluate our method on real-world data measured on Belgian railway tracks. Our model achieves promising results on connected classes, exposed to only a few annotated samples at test time.
In recent years, PCs have become very popular for a wide range of applications, such as immersive virtual reality scenarios. As a consequence, in the last couple of years, there has been a great effort to develop novel acquisition, representation, compression, and transmission solutions for PC contents in the research community. In particular, the development of objective quality assessment methods that are able to predict the perceptual quality of PCs. In this paper, we present an effective novel method for assessing the quality of PCs, which is based on descriptors that extract perceptual color distance-based texture information of PC contents, called Perceptual Color Distance Patterns (PCDP). In this framework, the statistics of the extracted information are used to model the PC visual quality. Experimental results show that the proposed framework exhibit good and robust performance when compared with several state-of-the-art point cloud quality assessment (PCQA) methods.
The United States of America has an estimate of 84,000 dams of which approximately 15,500 are rated as high-risk as of 2016. Recurrent geological and structural health changes require dam assets to be subject to continuous structural monitoring, assessment and restoration. The objective of the developed system is targeted at evaluating the feasibility for standardization in remote, digital inspections of the outflow works of such assets to replace human visual inspections. This work proposes both a mobile inspection platform and an image processing pipeline to reconstruct 3D models of the outflow tunnel and gates of dams for structural defect identification. We begin by presenting the imaging system with consideration to lighting conditions and acquisition strategies. We then propose and formulate global optimization constraints that optimize system poses and geometric estimates of the environment. Following that, we present a RANSAC frame-work that fits geometric cylinder primitives for texture projection and geometric deviation, as well as an interactive annotation frame-work for 3D anomaly marking. Results of the system and processing are demonstrated at the Blue Mountain Dam, Arkansas and the F.E. Walter Dam, Pennsylvania.
To improve the driving safety triggered by driver’s behavior recognition in an in-car environment, we propose to use depth cameras mounted in a car to generate behavior models generated by a deep learning algorithm for a driver’s behavior classification. The contribution of this paper is trifold: 1) The proposed multi-view driver behavior recognition system can handle the occlusion problem happened in one of the cameras; 2) Using the recurrent neural network can effectively recognize the continuous time behavior; 3) the average recognition accuracy of proposed systems can achieve 83% and 88%, respectively.
Efficient plant phenotyping methods are necessary to accelerate the development of high yield biofuel crops. Manual measurement of plant phenotypes, such as height is inefficient, labor intensive and error prone. We present a robust, LiDAR based approach to estimate the height of biomass sorghum plants. A vertically oriented laser rangefinder onboard an agricultural robot captures LiDAR scans of the environment as the robot traverses between crop rows. These LiDAR scans are used to generate height contours for a single row of plants corresponding to a given genetic strain. We apply ground segmentation, iterative peak detection and peak filtering to estimate the average height of each row. Our LiDAR based approach is capable of estimating height at all stages of the growing period, from emergence e.g. 10 cm through canopy closure e.g. 4 m. Our algorithm has been extensively validated by several ground truthing campaigns on biomass sorghum. These measurements encompass typical methods employed by breeders as well as higher accuracy methods of measurement. We are able to achieve an absolute height estimation error of 8.46% ground truthed via ?by-eye? method over 2842 plots, an absolute height estimation error of 5.65% ground truthed at high granularity by agronomists over 12 plots, and an absolute height estimation error of 7.2% when ground truthed by multiple agronomists over 12 plots.
By combining terrestrial panorama images and aerial imagery, or using LiDAR, large 3D point clouds can be generated for 3D city modeling. We describe an algorithm for change detection in point clouds, including three new contributions: change detection for LOD2 models compared to 3D point clouds, the application of detected changes for creating extended and textured LOD2 models, and change detection between point clouds of different years. Overall, LOD2 model-to-point-cloud changes are reliably found in practice, and the algorithm achieves a precision of 0.955 and recall of 0.983 on a synthetic dataset. Despite not having a watertight model, texturing results are visually promising, improving over directly textured LOD2 models.