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A generalized approach for producing,quantifying, and validating citizen science data from wildlife images 总被引:1,自引:0,他引:1 下载免费PDF全文
Alexandra Swanson Margaret Kosmala Chris Lintott Craig Packer 《Conservation biology》2016,30(3):520-531
Citizen science has the potential to expand the scope and scale of research in ecology and conservation, but many professional researchers remain skeptical of data produced by nonexperts. We devised an approach for producing accurate, reliable data from untrained, nonexpert volunteers. On the citizen science website www.snapshotserengeti.org , more than 28,000 volunteers classified 1.51 million images taken in a large‐scale camera‐trap survey in Serengeti National Park, Tanzania. Each image was circulated to, on average, 27 volunteers, and their classifications were aggregated using a simple plurality algorithm. We validated the aggregated answers against a data set of 3829 images verified by experts and calculated 3 certainty metrics—level of agreement among classifications (evenness), fraction of classifications supporting the aggregated answer (fraction support), and fraction of classifiers who reported “nothing here” for an image that was ultimately classified as containing an animal (fraction blank)—to measure confidence that an aggregated answer was correct. Overall, aggregated volunteer answers agreed with the expert‐verified data on 98% of images, but accuracy differed by species commonness such that rare species had higher rates of false positives and false negatives. Easily calculated analysis of variance and post‐hoc Tukey tests indicated that the certainty metrics were significant indicators of whether each image was correctly classified or classifiable. Thus, the certainty metrics can be used to identify images for expert review. Bootstrapping analyses further indicated that 90% of images were correctly classified with just 5 volunteers per image. Species classifications based on the plurality vote of multiple citizen scientists can provide a reliable foundation for large‐scale monitoring of African wildlife. 相似文献
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选取同天过境的Landsat5TM和HJ-1B红外相机数据,在获取3个大气参数后,结合辐射传输模型分别对大亚湾核电基地附近海域海表温度和温排水温升区的分布情况进行遥感监测,对比结果显示,环境卫星遥感监测数据与TM数据监测所得温排水在空间分布上具有较高一致性,二者反演出的绝对温度相差不超过1.1℃,相同温升等级范围内的相对温度均值也不超过0.4℃.因此,HJ-1B红外相机可满足核电站热污染的监测需求. 相似文献
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为了解决安全生产部门对危化品仓存储缺乏有效技术手段的问题,构建了五元组参数单目视觉成像模型并提出一种相机标定方法。该方法无需已知相机内参数信息,仅通过2个标识点成像关系就可实现参数标定,避免了传统算法实现过程复杂、运算量大等问题。标定得到的参数作为堆垛三维几何重建运算的基本条件,重建的效果则客观评价了标定参数的精确性。试验结果表明:提出的标定算法易于实现,其结果在堆垛几何重建过程中有较强的鲁棒性,重建结果与实际情况比较误差很小,适用于危化品仓储五距的监管。 相似文献
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PaulR. Wolf Terrence J. Keating 《Journal of the American Water Resources Association》1973,9(2):312-319
ABSTRACT Necessary input parameters for studying mixing zone characteristics of thermal plumes are horizontal surface and subsurface water velocities. Using time lapse aerial photography and analytical photogrammetric techniques, movements of drogues in an effluent plume were traced. From these traces accurate velocity vectors were obtained. Photographic coordinates of drogue images were measured using a glass scale. From the photo coordinates and the results of a ground control survey, an analytical solution was made for positions of drogues in the water at known intervals of time. Drogue positions were mapped for selected exposures thereby providing a visual display of velocity vectors in the study area. A rigorous error analysis was performed to determine the validity of the computed results. 相似文献
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地处亚洲东部的中国长春,蒙古乌兰巴托和日本鹿儿岛,作为亚洲沙尘暴的地面监测站点,用数码相机全自动定时拍摄记录天空的数字照片,通过分析数字照片数据上像素点的信息和建筑的能见度,来判断沙尘暴事件的发生及强度。对比分析了2005年-2008年冬春季节数字监测数据与NOAA,MT-SAT和Terra,Aqua/MOD IS的卫星遥感图片以及其他相关沙尘天气的报道。在监测的图片数据上,持续1-2天的强沙尘暴天气能够被清楚的识别,轻度的沙尘天气与云量较多的天气较难区别。 相似文献
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Examining driver behavior using data gathered from red light photo enforcement cameras 总被引:1,自引:0,他引:1
INTRODUCTION: To develop an effective driver assistance system that can prevent red light violations, it is important to have a thorough understanding of contributing factors and circumstances surrounding such violations. METHODS: Red light violation behavior was examined using about 47,000 violation records that were captured by photo enforcement cameras from 11 signalized intersections in the city of Sacramento, California, over a four-year period. This examination identified factors with strong correlation to red light running behavior. RESULTS: Key findings based on Sacramento's red light violation records include: (a) younger drivers showed a higher tendency of running the red light and were more likely to commit such a violation at speeds above the posted speed limit; (b) off-peak time period between 8 p.m. to 5 a.m. had lower violation counts, but red light violators in this time frame had a higher propensity of racing through intersections at high speeds; (c) also during the time period between 8 p.m. to 5 a.m., violators showed a higher probability of entering intersections two or more seconds after the onset of red light; and (d) violators were less likely to cross high traffic-volume intersections with speeds greater than the posted speed limit. DISCUSSION: Sacramento's data suggest that some red light violators might have committed such an offense unintentionally. The top three violation speeds were all below 20 mph and more than 94% of red light runners crossed intersections within 2 seconds after the onset of the red light. IMPACT ON INDUSTRY: In the next several years, studies will be executed to assess whether a red light violation warning system can reduce "unintentional red light running" such as drivers who made incorrect judgment regarding the adequate time to clear the intersection and inattentive motorists who fail to observe the presence and status of the red light. 相似文献
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SWDC数字航空摄影仪在特大地震灾害中的应用 总被引:1,自引:0,他引:1
我国是一个自然灾害频发的国家,汶川大地震产生的巨大破坏将国家减灾救灾的战略需求提到了更高的地位.利用国产SWDC数字航空摄影仪等航空遥感平台,在灾前预警、灾中应急和灾后重建等不同阶段获取及时、准确、有效的灾害数据,是减灾救灾的重要组成内容.阐述了SWDC在灾中应急与灾后详评估中采用的技术方案,并于2008年5月16日、18日、21日三次获取了北川、平武、安县和青川等县市的航空遥感影像,制作了北川县地质灾害分布图、灾区公路损毁分布图等图件.在此基础上,对SWDC的数据快速获取能力和高精度的灾害详评估进行了着重论述.最后,分析了灾害应急航空遥感数据处理的现状,对各种处理手段进行了对比分析,并对航空遥感的未来发展进行了展望. 相似文献
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A. Matarrese F. Mastrototaro G. D'onghia P. Maiorano A. Tursi 《Chemistry and Ecology》2004,20(5):377-386
Side-scan sonar and underwater video camera records as well as dredging samples were used to map the bottom morphology and biocoenoses in the Taranto seas. A 1:20,000 scale chart has been produced with all the data recorded. Most of the study area consists of biocoenoses affected by the anthropogenic activities of the town of Taranto. Some native broadly tolerant species seem to benefit from these activities and become increasingly dominant. Environmental modifications also seem to favour the settlement of exotic species. 相似文献