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鱼眼图像轮廓提取算法研究 总被引:6,自引:0,他引:6
要从鱼眼图像恢复出实际场景的图像,其前提是必须准确地提取出鱼眼图像的轮廓,也就是说要精确地求出鱼眼图像圆形区域的半径和圆心坐标。提取鱼眼图像轮廓一般是采用最小二乘拟和的方法,但该方法计算量大,精度难以保证。文中根据鱼眼图像的特点提出了面积统计的方法。面积统计法不仅可以降低计算复杂度,在精度上也可以达到要求,实验证明了所给出的方法的正确性和可行性。 相似文献
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预测蛋白质交互作用(Protein-Protein Interaction,PPI)网络中未知蛋白质的功能,是生物信息学的一个研究热点.目前基于功能流的方法能有效地解决PPI网络的聚类问题,但是其正确率偏低、时间复杂度较高.为此提出了一种融合人工鱼群机理的PPI网络聚类模型与算法:将人工鱼看作一组聚类中心,觅食行为是指从每个聚类中心开始向它的邻接结点搜索并添加结点到该聚类模块中;接下来将目标函数值最大的人工鱼对应的一组聚类模块看作初始的聚类结果,对应鱼群的追尾行为;剩下的人工鱼开始执行聚群行为,判断对应的聚类模块与初始的聚类结果之间的相似度.如果相似度低于给定的阈值,则将聚类模块添加到初始的聚类结果中.PPI数据集上的仿真实验表明,该算法可以自动确定聚类数目,而且聚类结果的正确率和算法的运行效率都优于功能流算法. 相似文献
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根据天然水库的地形条件,结合某水库网箱养鱼带周围的水质监测,构建了有风条件下水库流场数值计算模型.在此基础上,对不同风速下该水库网箱带对周边水域水质浓度变化进行模拟.计算结果表明,同等条件下,自然风速小于7.5 m/s时,与无风时差异甚小;自然风速等于8.5 m/s时,粪大肠菌群、DO和BOD5有效横向衰减系数分别增大0.0016,0.0017和0.0032,影响范围分别扩大22.62%,19.50%和18.67%.进一步证实了风成流的形成对水库生态环境的影响. 相似文献
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This study quantified the unique variation in stream fish and habitat and a land use disturbance index (LDI) at a variety of spatial scales: catchment, eight riparian polygons that varied in width and length (e.g. 50 m to all upstream reaches), upstream polygons of 1.6 and 3.2 km and the residual upland area of each site watershed not accounted for by each polygon. The analyses confirmed a hockey stick‐shaped relationship between the fish community and the LDI, with sensitive species only present below an LDI of 11. The largest variation for most metrics was explained by the largest polygons, suggesting that local riparian conditions were not as important predictors of stream condition. LDI in upland areas, where zero‐order streams occur, was also an important predictor of fish biomass and taxa richness. Contrary to expected, additive models with both catchment and riparian corridors provided minimal increases in predictive power, and no improvement in model performance occurred when data sets were stratified into sites below the LDI threshold. Finally, there was considerable covariation in the template and stressor predictor variables that made it difficult to quantify the unique variation in biological and physical responses accounted for by land use. That the 1600‐m proximal polygon provided the best predictor of the fish community and temperature is supportive of there being some proximal effects of land use. Overall, our findings suggest that stream management must consider processes that occur in the entire upstream catchment and the entire riparian corridor, including the headwaters for success. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Hydropeaking dam operation and water extractions for irrigation have been broadly stated as alterations to natural flow regimes, which have also been noticed in the Biobío Watershed, in Central Chile, since 1996. In the Biobío River, most of native fish species are endemic and very little is known about them. Their ecological and social values have never been estimated, and there is lack of information about their habitat preferences. Furthermore, changes on fish habitat availability due to natural and/or man‐made causes have not been evaluated. In this study, eight native fish species, in a representative reach of the Biobío River, were studied and their preferred habitats were surveyed and characterized. A hydrodynamic model was built and linked to the fish habitat simulation model CASiMiR. Fuzzy rules and fuzzy sets were developed for describing habitat preference of the native fish species. CASiMiR was then used to simulate how physical habitat conditions vary due to flow control (i.e. upstream dams). Results show how overall habitat quality, expressed as weighted usable area (WUA) and hydraulic habitat suitability (HHS), changes and fluctuates due to the dam operation and how the daily hydropeaking is influencing quantity, quality and location of different habitats. The study suggests that the analysed fish are highly susceptible to flow control, as dams are currently operated, and fish habitat improvement suggestions are proposed. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献