一种四叉树和测地线活动轮廓模型相结合的海陆影像分割方法   总被引：1，自引：0，他引：1  

郭海涛  孙磊  申家双  陈小卫  张宏伟 《测绘学报》2016,45(1):65-72

海陆影像分割对于后续的海岸线提取、潮间带地形反演、海岸演化状况分析等都具有十分重要的意义。本文在分析了四叉树、测地线活动轮廓(GAC)模型和Canny边缘检测算子等在海陆影像分割中优缺点的基础上,提出了一种四叉树、Canny算子和GAC模型相结合的海陆影像分割方法。该方法综合利用上述各方法的优点,将Canny算子边缘检测结果融入到基于四叉树初分割的GAC模型中,重构边界停止函数,演化水平集方程,实现海陆影像分割。试验结果表明,该方法具有海陆影像分割速度快、精度高、可靠性强和自动化程度高等优点,对于弱边缘以及严重凹陷边缘,都能实现自动和准确分割。  相似文献   

热红外与可见光数据的云边缘高度匹配     

李彬  辛晓洲  张海龙  胡继超 《遥感学报》2016,20(6):1435-1445

高分辨率数据中云高度的差异性突显,特别是边缘处高度在云阴影识别和地表辐射估算等方面成为需要考虑的重要因素。热红外数据获取云高度分辨率较低、缺乏细部差异性特征,为解决这一问题,首先将对应的热红外和可见光数据进行特征点配准,再将基于热红外数据计算的云高度重采样至高分辨率,然后以基于欧式距离变换的围线搜索方法及距离加权将热红外云边缘高度匹配至对应的可见光图像,最后根据云阴影的相似度匹配方法确定真实云高度。结果表明,算法在遵循热红外云高信息分布变化规律的同时,可以得到较准确的高分辨率云边缘高度,一定程度上解决了热红外技术获取云高在分辨率上的局限,扩展了其在云高反演方面的作用。  相似文献   

地表覆盖遥感产品更新完善的研究动向     

陈军  张俊  张委伟  彭舒 《遥感学报》2016,20(5):991-1001

近年来,多尺度地表覆盖遥感产品的不断涌现,为环境变化研究、地球系统模拟、地理国(世)情监测和可持续发展规划等提供了重要科学数据。为更好地满足广大用户日益增长的应用需求,应对地表覆盖遥感产品进行持续更新完善,保持其时效性、增强时序性、丰富多样性。针对大面积地表覆盖遥感产品更新完善所面临的主要问题,介绍和评述了国内外有关研究动向,包括影像与众源信息相结合的更新、数据类型细化与完善、地表覆盖真实性验证,并作了简要展望。  相似文献   

双频BDS实时精密单点定位算法和精度分析     

刘国仕  薛建华  付文举 《测绘科学》2016,41(10):44-47

为了对BDS实时精密单点定位性能进行评估,该文提出了一种适用于BDS系统的实时精密单点定位算法。采用无电离组合模型作为双频实时精密单点定位的数学模型,采用电离层残差法和Melbourne-Wübbena组合实时探测相位周跳,进而单历元实时估计坐标、模糊度等参数,实现了BDS双频实时精密单点定位算法。基于此算法,采用轨道钟差产品和采样间隔为1s的观测数据,模拟实时BDS双频精密单点定位算法,并评估其定位精度。实验结果表明:BDS双频实时定位的平面精度和三维精度均为0.2m左右。  相似文献   

高压下天然菱铁矿的压缩性和电子结构研究     

高静  巫翔  秦善  张硕  杨科  李晓东 《岩石矿物学杂志》2016,35(2):276-282

采用同步辐射光源和金刚石对顶砧(DAC)技术,对天然菱铁矿的压缩性和电子结构进行了原位X射线衍射(XRD)和X射线吸收近边结构谱(XANES)测试研究。在室温下随着压力逐渐升高至50.2 GPa,菱铁矿保持方解石型结构不变,但是逐渐向Na Cl型结构转变;刚性[CO3]2-基团平行于ab-平面定向排列使c轴的压缩性大于a轴。菱铁矿在44.6~47.1 GPa之间发生电子由高自旋态(HS)向低自旋态(LS)的转变,表现为体积塌陷8%。HS菱铁矿的等温状态方程参数为K0=112(5)GPa和K'0=4.6(3)。首次采用XANES技术对菱铁矿中Fe2+的电子结构进行了研究,结果表明:随着压力升高至37.3 GPa,Fe2+的配位和局域对称并未发生明显变化;此后电子结构开始转变,Fe2+的3d轨道分裂能降低,电子跃迁概率增大,呈现LS特性。  相似文献   

A synthetic aperture radar sea surface distribution estimation by n-order Bézier curve and its application in ship detection   总被引：1，自引：0，他引：1  

郎海涛  张杰  王一多  张晰  孟俊敏 《海洋学报(英文版)》2016,35(9):117-125

To dates,most ship detection approaches for single-pol synthetic aperture radar(SAR) imagery try to ensure a constant false-alarm rate(CFAR).A high performance ship detector relies on two key components:an accurate estimation to a sea surface distribution and a fine designed CFAR algorithm.First,a novel nonparametric sea surface distribution estimation method is developed based on n-order Bézier curve.To estimate the sea surface distribution using n-order Bézier curve,an explicit analytical solution is derived based on a least square optimization,and the optimal selection also is presented to two essential parameters,the order n of Bézier curve and the number m of sample points.Next,to validate the ship detection performance of the estimated sea surface distribution,the estimated sea surface distribution by n-order Bézier curve is combined with a cell averaging CFAR(CA-CFAR).To eliminate the possible interfering ship targets in background window,an improved automatic censoring method is applied.Comprehensive experiments prove that in terms of sea surface estimation performance,the proposed method is as good as a traditional nonparametric Parzen window kernel method,and in most cases,outperforms two widely used parametric methods,K and G0 models.In terms of computation speed,a major advantage of the proposed estimation method is the time consuming only depended on the number m of sample points while independent of imagery size,which makes it can achieve a significant speed improvement to the Parzen window kernel method,and in some cases,it is even faster than two parametric methods.In terms of ship detection performance,the experiments show that the ship detector which constructed by the proposed sea surface distribution model and the given CA-CFAR algorithm has wide adaptability to different SAR sensors,resolutions and sea surface homogeneities and obtains a leading performance on the test dataset.  相似文献   

Seismic attenuation estimation using a complete ensemble empirical mode decomposition-based method     

《Marine and Petroleum Geology》2016

The frequency attenuation gradient method can provide important information for hydrocarbon detection. In this paper, a method using Complete Ensemble Empirical Mode Decomposition (CEEMD), Hilbert transform and the least-squares curve-fitting is proposed for seismic attenuation estimation as an effective frequency attenuation gradient estimation approach. We first use CEEMD to obtain the different Intrinsic Mode Functions (IMFs), which have a narrow band and can enhance the physical meaning of instantaneous attributes trace by trace. The time-frequency spectrum, which is computed using a Hilbert transform of each IMF, is represented as a spectrum with a single-peak that has narrow side lobes, which is conducive to frequency attenuation gradient estimation. Second, for each time sample, the frequency-amplitude spectrum of each IMF trace is extracted from the time-frequency spectrum to conduct the attenuation gradient computation. Then, the logarithm operation is performed for each IMF trace. Due to the very narrow bands of some IMFs in some seismic traces, a variable frequency window is adopted along the IMF trace according to the local data characteristics. Finally, the attenuation gradient for each IMF in a seismic trace can be computed using least-squares fitting. A different IMF reflects a seismic trace with a different spatiotemporal scale and can highlight different geologic and stratigraphic information. The correlation weighted average operation is used to highlight some useful details in seismic trace and obtains the attenuation gradient for each seismic trace. Field data examples demonstrate our method and its effectiveness. The proposed method can stably estimate the frequency attenuation gradient.  相似文献   

高频地波雷达海杂波背景下的船只目标检测研究进展     

王祎鸣 《海洋科学》2016,40(10)

针对海杂波对高频地波雷达目标检测的干扰问题,分目标处于海杂波谱区之内和之外两种情况综述了海杂波背景下的目标检测方法。对于海杂波内目标检测的难题,介绍了一种基于现场海态同步观测信息的检测新思路以及初步验证结果。对国内外相关研究进展的归纳总结和新思路的提出,为提出更加有效的海杂波干扰下的目标检测方法提供了重要的参考。  相似文献   

Copper Speciation in a Collection of Geochemical Reference Materials Using Sequential Extraction and Evaluation of the Validity Using XANES Spectroscopy          下载免费PDF全文

Atsuyuki Ohta  Ran Kubota 《Geostandards and Geoanalytical Research》2016,40(1):117-134

Copper speciation in a collection of Japanese geochemical reference materials (JSO‐1, JLk‐1, JSd‐1, ‐2, ‐3 and ‐4, JMs‐1 and JMs‐2) was achieved by sequential extraction and characterised using X‐ray absorption near‐edge structure spectroscopy. In the first step of the extraction, referred to as the acid fraction, between 1% and 20% total Cu within the reference materials was extracted. Such a result is typically accounted for by absorption of Cu onto clay minerals. However, the presence of Cu sulfate (an oxidation product of chalcopyrite) was observed in some of the stream sediments affected by mining activity (JSd‐2 and JSd‐3) instead. Copper was extracted in the reducible fraction (targeting Fe hydroxide and Mn oxide) (2–49% total Cu). Between 2% and 51% Cu was extracted in the oxidised fraction (targeting sulfides and organic matter). X‐ray absorption near‐edge structure spectroscopy clarified that the reducible fraction consisted of Cu bound to Fe hydroxide, whereas the oxidised fraction was a mixture of Cu bound to humic acid (HA) and Cu sulfide. In the oxidisable fraction, chalcopyrite was the predominant species identified in JSd‐2, and Cu bound to HA was the major species identified in JSO‐1 (a soil sample).  相似文献   

川东长兴组台缘礁滩相储层纵向非均质性特征及形成机制——以川东宣汉盘龙洞长兴组剖面为例     

秦鹏  胡忠贵  吴嗣跃  左洺滔  韩露 《岩石矿物学杂志》2018,37(1):61-74

近几年,随着四川盆地海相碳酸盐岩储层勘探的不断加强,碳酸盐岩储层强的非均质性已成为制约礁滩气藏勘探开发的现实问题。以川东宣汉盘龙洞长兴组典型台缘礁滩剖面为研究对象,通过对典型台缘礁滩野外剖面的精细观察,结合镜下薄片及岩矿资料分析,重点探讨了盘龙洞礁滩储层纵向非均质性特征及成因。剖面上礁滩体垂向上存在很强的旋回性和储层非均质性,其储集岩分布、储层厚度、白云岩化程度、溶蚀作用等受海平面周期性的升降变化影响而呈现周期性变化。礁滩储层非均质性受高能相带、海平面升降变化和建设性成岩作用的共同控制,高能相带控制储层原生孔隙的发育,决定了储层的沉积非均质性,白云岩化和溶蚀作用有利于礁滩体储层的形成,大气淡水淋滤改造对于优化储层具有关键作用,海平面升降变化决定了礁滩体旋回性发育,而建设性成岩作用的选择性改造深化了储层非均质性。  相似文献