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We present the SphericRTC system for real-time 360-degree video communication. 360-degree video allows the viewer to observe the environment in any direction from the camera location. This more-immersive streaming experience allows users to more-efficiently exchange information and can be beneficial in the real-time setting. Our system applies a novel approach to select representations of 360-degree frames to allow efficient, content-adaptive delivery. The system performs joint content and bitrate adaptation in real-time by offloading expensive transformation operations to the GPU via CUDA. The system demonstrates that the multiple sub-components -- viewport feedback, representation selection, and joint content and bitrate adaptation -- can be effectively integrated within a single framework. Compared to a baseline implementation, views in SphericRTC have consistently higher visual quality. The median Viewport-PSNR of such views is 2.25 dB higher than views in the baseline system.

360-degree video is an emerging medium that presents an immersive view of the environment to the user. Despite its potential to provide an immersive watching experience, 360-degree video has not achieved widespread popularity. A significant cause of this slow adoption is the high-bandwidth requirements of the format. The primary source of bandwidth inefficiency in 360-degree video streaming, un-addressed in popular transmission methods, is the discrepancy between the pixels sent over the network (typically the full omnidirectional view) and the pixels displayed in the head-mounted display's field of view. At worst, roughly 88% of transmitted pixels remain unviewed. In this work, we motivate a user-adaptive approach to address inefficiencies in 360-degree streaming through an analysis of user-viewing traces. We design a greedy algorithm to generate projections of the spherical surface that allow the user-view trajectories to be efficiently transmitted. We further demonstrate that our approach can be applied to many popular 360-degree projection layouts. In BD-rate experiments, we show that the adaptive versions of the rotated spherical projection (RSP) and equi-angular cubemap (EAC) can save 26.2% and 24.0% bitrates on average, respectively, while achieving the same visual quality of rendered views compared to their non-adaptive counterparts in a realistic scenario. These adaptive projections can also achieve 53.1% bandwidth savings over the equirectangular projection.

Riparian soils and vegetation are important factors influencing the biodiversity and biogeochemical processes of river ecosystems. Riparian soils and vegetation form the foundation for multiple ecosystem services provided by river ecosystems. However, it remains poorly understood how riparian soils and vegetation interact with one another to maintain these services. In this study, we sampled four common types of riparian vegetation associated with the Beijiang River in South China. These included forestland, bamboo forest, mixed forest, and grassland ecosystems. Specifically, we analyzed the spatial distribution of riparian soils and their response to environmental factors (i.e., coverage and height of trees, shrubs and grass, distance to river, and altitude). Our results indicate that soil properties in riparian zones were affected significantly by vegetation type. In particular, clay content, soil organic carbon, and nitrate nitrogen content were significantly correlated with vegetation type. In contrast, changes in soil total nitrogen, total phosphorus, and available phosphorus content were not associated with vegetation type. Moreover, soil physical and chemical properties interacted with one an other, as well as with vegetation characteristics. This was indicated by the significant correlation observed between soil organic carbon, total nitrogen, total phosphorus, and soil texture, with structural characteristics of the four vegetation types. We also found that height and cover of trees and shrubs were significantly correlated with soil chemical properties. However, the effects of topographic variables such as altitude and distance to river were not significant. Results from this study can thus provide a basis for the ecological restoration and land management of degraded iparian zones.

The water-sediment regulation scheme (WSRS) of dams influences the desorption, resuspension, and deposition processes of riparian sediments, which in turn affect the spatial-temporal variations of heavy metals (HMs) in riparian sediments and leads to severe degradation of soil and water quality. However, the difference between the trapping effect of dams and the redistribution effects of the WSRS on HMs in riparian sediments, as well as the consecutively seasonal change of HMs after the WSRS, are rarely reported. To fill this gap, the concentrations of six HMs including Cd, Cr, Cu, Ni, Pb, and Zn in riparian sediments along the Xiaolangdi Dam (XLD) Reservoir and its downstream reach were investigated, and the contamination level and potential ecological risk of HMs were assessed, to differentiate the effects of the XLD and its WSRS on the concentration, contamination level, and potential ecological risks of HMs. The results indicated that the mean HM concentrations in riparian sediments were higher than the background values in the study area and showed significant spatial and temporal variations. However, the regional differences of HM concentrations caused by the trapping effect of the XLD were less than the seasonal differences caused by the redistribution effects of the WSRS. The contamination and ecological risk assessment indicated that riparian sediments in the study area were contaminated by the six HMs, particularly by Cd and Pb, which overall exhibited a high and moderate ecological risk, respectively. The sources for Pb were likely agricultural inputs, while the sources for Cd should be attributed to both industrial and agricultural inputs. Overall, the trapping effect of the XLD led to the accumulation of HMs in riparian sediments along the reservoir area, while the regulation effects of the WSRS resulted in the redistribution of HMs in riparian sediments from the reservoir area to the downstream reach.

Assessing spatiotemporal variation in water quality and heavy metals concentrations in wetlands and identifying metal contamination source are crucial steps for the protection and sustainable utilization of water resources. Using the water quality identification index (Iwq), heavy metal pollution index (HPI), hierarchical cluster analysis (HCA) and redundancy analysis (RDA), we evaluated spatiotemporal variation in water quality and heavy metals concentrations, and their interrelation in wetlands along the middle and lower Yellow River. The average Iwq was highest during flood season but the average HPI was lowest in the same season. Meanwhile, the trend in mean HPI across three hydrological seasons was the opposite to that of mean Iwq. There was significant variation in wetlands water pollution status across seasons. During the flood season, the wetlands in the affected area with hanging river were seriously polluted. In other seasons, pollution in the artificial wetlands was even more severe. Moreover, serious pollution of wetlands in belt transect #03 (Yuanyang-Zhongmu) was more frequent. Dissolved oxygen and chemical oxygen demand strongly influenced heavy metal concentrations, while other water quality parameters had different influences on heavy metal concentrations in different hydrological seasons. The causes of water pollution were divided into natural factors and human disturbance (with potential relationships between them). The polluted wetlands were greatly affected by the Yellow River during the flood season while they were more impacted by agricultural and domestic sewage discharge in other seasons. However, heavy metal deposition and leaching into riparian wetlands were still affected by diverse channel conditions. If this trend is allowed to continue unabated, wetlands along the middle and lower Yellow River are likely to lose their vital ecological and social functions.

360-degree video streaming is an emerging technology that provides immersive experiences to users. However, it both requires high streaming bandwidth and wastes a significant portion of the bandwidth. To improve bandwidth-efficiency, researchers have proposed oriented projections and FOV rendering. However, existing software and tools are unable to perform these tasks in an online manner under stringent processing latency and throughput constraints. In this paper, we present FFmpeg360, an open source software that leverages the GPU to accelerate video processing, making it possible to deploy video transformation tasks on edge computing devices. In addition, "view videos" generated by FFmpeg360 can be used to compare visual quality of views rendered from various spatial and bitrate adaptation schemes designed for 360-degree video streaming.

This artifact includes source code, scripts and datasets required to reproduce the experimental figures in the evaluation of the MM'18 paper, which is entitled "MiniView Layout for Bandwidth-Efficient 360-Degree Video". The artifact reports the comparison results among the standard cube layout (CUBE), the equi-angular layout (EAC), and the MiniView layout (MVL) in terms of compressed video size, visual quality of views and decoding and rendering time.

Determining the relationship between plant functional traits and the environment are key for the protection and sustainable utilization of riparian wetlands. In the middle and lower reaches of the Yellow River, riparian wetlands are divided into seasonal floodplain wetlands (natural) and pond-like wetlands or paddy fields (artificial). Here, species composition differences were catalogued based on plant functional traits including origin, life history, and wetland affinity in natural and artificial wetlands. Wetland physicochemical characteristics and regional socio-economic parameters collected as indicators of environmental variables were used to analyze the plant functional trait-environment relationship. The results reveal that plant functional traits in the seasonal floodplain wetland are impacted by physicochemical characteristics of habitat. The abundance of annual plants tends to decrease with concentration of heavy metals, while species diversity is mainly determined by soil physical and chemical properties, especially soil pH and temperature. Specifically, wetland-obligate species (not in water) are more resistant to heavy metal content in water than species with other types of wetland affinity. Life history strategies of species in artificial sites tend to be significantly associated with animal husbandry and artificial populations, while the wetland affinity of species is mainly determined by regional agriculture, especially the installation of agricultural covered areas. Furthermore, water quality and nutrients in suspended sediments from the Yellow River affected species diversity and life history strategies by affecting water and soil conditions of surrounding wetlands, especially conductivity and phosphorus levels.

With the recent increase in popularity of VR devices, 360-degree video has become increasingly popular. As more users experience this new medium, it will likely see further increases in popularity as users experience its greater immersiveness compared to traditional video streams. 360-degree video streams must encode the omnidirectional view, and, with current encoding techniques, these views require significantly higher bandwidth than traditional video streams. These larger bandwidth requirements comprise the main barrier toward wider adoption by video streaming services. To reduce bandwidth requirements of 360-degree streaming, we propose the MiniView Layout. Compared to the standard cube layout, with equal pixel densities, 360-degree videos encoded in the MiniView Layout can save 16% of the encoded video size while delivering similar visual qualities. In conjunction with the MiniView Layout, we make the following contributions toward improving the 360-degree video ecosystem: i) We create a "projection efficiency" metric that quantifies the efficiencies of sphere-to-2D projections. ii) We introduce the ffmpeg360 tool. ffmpeg360 transcodes 360-degree videos and measures comparative 360-degree video quality given user head movement traces. The tool performs these tasks efficiently, using OpenGL for GPU acceleration.

Riparian vegetation plays a vital role in inhibiting soil and water loss, but few studies have quantified the relationships between vegetation spatial pattern and the hydraulic characteristics of upslope runoff. This study investigated how hydraulic characteristics (e.g., runoff coefficient, flow regime, flow resistance, and flow shear stress of overland flow) responded to differences in vegetation cover (15% and 30%), slope gradient (5&deg, 10&deg, 15&deg, and 20&deg, ), and vegetation pattern in the riparian zone along the lower Yellow River, China, based on landscape pattern analysis and a runoff scouring experiment with flow rates of 9 and 15 L/min and an experimental plot size of 1 m &times, 3 m. We found that runoff generation on shallow slopes was moderated by increasing vegetation cover, but that this moderating effect decreased on steeper slopes. The regime of overland flow switched from laminar and subcritical on the 5&deg, slope (Fr = 0.56&ndash, 0.87) to laminar and critical on the 10&deg, slopes (Fr = 1.02&ndash, 2.18). Flow resistance increased with vegetation cover and flow rate and decreased with slope gradients, and it was larger on shallow slopes with high vegetation cover. Flow shear stress had a range of 1.42&ndash, 3.55 N m&minus, 2, and it increased with increasing slope gradient, vegetation cover, and flow rate. The hydraulic characteristics of upslope runoff, especially flow resistance, were significantly related to vegetation pattern at both the landscape and class levels. Flow resistance was negatively related to patch density, and positively related to perimeter&ndash, area fractal dimension and connectance index. The influencing mechanism of landscape patterns on soil erosion processes is dependent on the landscape scale, since the relationships between flow resistance and some landscape pattern indices (aggregation index, effective mesh size, and splitting index) were opposite at the landscape level compared to the class level. We conclude that fragmented vegetation distributions reduce flow resistance, and that riparian vegetation could be managed to inhibit slope erosion by increasing flow resistance.