共查询到20条相似文献，搜索用时 62 毫秒
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角锥棱镜直角误差斜入射法检测的理论分析 总被引：2，自引：0，他引：2
以矢量形式的折射,反射定律为基础,详细推导了角锥棱镜直角误差δ与分划板自准直双像间距ｔ之间的关系,提出了基于斜入射法,利用自准直平行光管直接测量角锥棱镜直角误差的光电检测系统,并进行了测量精度的理论分析。 相似文献
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针对500 m口径射电天文望远镜(FAST)主动反射面的测量,提出一种使用角锥棱镜的新方法,即将角锥棱镜顶点与反射面节点重合安置在FAST反射面板上,四块棱镜拼成一种可全方位观测的测量目标。为了解决该测量目标引入的系统误差,分析角锥棱镜作为测量目标时角度观测量和距离观测量与入射角的关系,给出角度观测的改正模型、距离观测改正模型以及坐标改正模型。实验结果表明该测量目标相对于圆棱镜的测量误差为±(1～3)mm左右。 相似文献
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盖鹏飞 《测绘科学技术学报》2010,27(3):196-199
为了克服传统自准直方法的缺陷,提出了两种新的自准直方法,即外觇标自准直法和基于智能全站仪的自动自准直法.外觇标自准直法不需要安装自准直灯,任何一台经纬仪或全站仪均可采用该法实现自准直功能,且不需要进行大范围调焦,减弱了调焦误差,能提高自准直测量精度.基于智能全站仪的自动自准直法,可以利用仪器的自动目标搜索功能,自动实现自准直,不仅克服了传统方法的缺陷,还省去了自准直测量中的人工精确照准,提高准直测量效率.经过理论推导及实验验证,所提出的两种方法正确可靠、操作筒单,且自准直测量的速度快、精度高. 相似文献
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角锥棱镜有效使用面积的计算 总被引：1，自引：1，他引：1
从理论上推导出角锥棱镜的主要光学性质，以及一定形状的棱镜有效面积随口径、入射角大小之间的变化规律，给出反映这种变化规律的图线，对正确使用角锥棱镜具有一定意义。 相似文献
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介绍了徕卡360°棱镜定位原理和结构特点,对该棱镜的性能指标(主要是棱镜的定位精度)进行了全面、系统的测试;给出了该棱镜定位精度的主要误差来源及其误差的大小和性质.首次发现徕卡360°棱镜的上棱镜面和上棱镜面的反射中心不一致,在垂直方向上存在5 mm的定位互差.分析了该棱镜偏转对棱镜定位精度的影响以及定位误差的变化规律,并给出其变化的原因.这为该棱镜的应用场合和使用方法提供了参考依据.建议在测量中尽可能地观测该棱镜的正对同一棱镜面,以避免不同棱镜面定位差别和棱镜偏转带来的影响. 相似文献
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盾构隧道施工测量中,对于联系测量的精度要求较高.为消除棱镜纵轴误差在联系测量短边处的影响,本文提出了调换棱镜顺序和棱镜"正倒镜法"两种方法,理论分析比较这两种方法,及其相对于传统测量方法的优越性.采用调换前后视棱镜的方法,偶数站时,可削弱甚至消除棱镜纵轴误差的影响.棱镜"正倒镜法",可完全消除纵轴误差对水平角的影响.对洞门中心测定运用最小二乘法,拟合出洞门所在的空间平面及空间球面,二者交线即为所求空间圆.通过某地铁盾构实际数据,结合盾构机进洞情况,验证了本文提出方法的可行性. 相似文献
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采用Landsat TM数据分析了阿克苏河—塔里木河断面水质污染状况,通过波段的DN值和常规监测数据建立能反映水质状况的
污染物监测模型。结果发现,将2000年常规监测数据代入模型后,与遥感数据的结果基本吻合| 重建阿克苏河—塔里木河的连续水体
污染变化曲线,得出污染物浓度随着远离上游而增加。 相似文献
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Monitoring drought dynamics in the Aravalli region (India) using different indices based on ground and remote sensing data 总被引：5，自引：0，他引：5
C. Bhuiyan R.P. Singh F.N. Kogan 《International Journal of Applied Earth Observation and Geoinformation》2006,8(4):289-302
The hard-rock hilly Aravalli terrain of Rajasthan province of India suffers with frequent drought due to poor and delayed monsoon, abnormally high summer-temperature and insufficient water resources. In the present study, detailed analysis of meteorological and hydrological data of the Aravalli region has been carried out for the years 1984–2003. Standardised Precipitation Index (SPI) has been used to quantify the precipitation deficit. Standardised Water-Level Index (SWI) has been developed to assess ground-water recharge-deficit. Vegetative drought indices like Vegetation Condition Index (VCI) and Temperature Condition Index (TCI) and Vegetation Health Index (VHI) have been computed using NDVI values obtained from Global Vegetation Index (GVI) and thermal channel data of NOAA AVHRR satellite. Detailed analyses of spatial and temporal drought dynamics during monsoon and non-monsoon seasons have been carried out through drought index maps generated in Geographic Information Systems (GIS) environment. Analysis and interpretation of these maps reveal that negative SPI anomalies not always correspond to drought. In the Aravalli region, aquifer-stress shifts its position time to time, and in certain pockets it is more frequent. In comparison to hydrological stress, vegetative stress in the Aravalli region is found to be slower to begin but quicker to withdraw. 相似文献
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Piyoosh Rautela Ramesh Chandra Lakhera 《International Journal of Applied Earth Observation and Geoinformation》2000,2(3-4)
The area around Sataun in the Sirmur district of Himachal Pradesh, India (falling between the rivers Giri and Tons; both tributaries of the Yamuna River) was studied for landslide vulnerability on behalf of the inhabitants. The study was made using extensive remote sensing data (satellite and airborne). It is well supported by field evidence, demographic and infrastructural details and aided by Geographic Information System (GIS) based techniques. Field observations testify that slope, aspect, geology, tectonic planes, drainage, and land use all influence landslides in the region. These parameters were taken into consideration using the statistical approach of landslide hazard zonation. Using the census data of 1991, vulnerability of the populace to the landslide hazard was accessed. As most of the infrastructure in the region is concentrated around population centres, population data alone was used for vulnerability studies. 相似文献
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ZHAN F. Benjamin 《地球空间信息科学学报》2011,(1)
Although it is well known that coseismic gravity changes take place during an earthquake, previous research has not yielded convincing evidence demonstrating that significant gravity changes occur before large earthquakes. Furthermore, even if we suspect that gravity changes occur before large earthquakes, we have yet to demonstrate how to consistently observe these changes for useful earthquake forecast that would bring benefits to society. We analyzed ground gravity survey data obtained in 1998, 2000, 200... 相似文献
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GNSS系统及其技术的发展研究 总被引：3，自引：1，他引：2
阐述了国际上卫星导航系统的总体发展,对美、俄、欧、中的四大全球系统,以及相关的区域系统和增强系统进行了简单的介绍,研究分析了GNSS系统及其技术的发展趋势,同时分析了我国Compass全球系统面临的机遇和挑战,并提出了我国未来工作的建议. 相似文献
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“4D”技术及其应用 总被引：13，自引：0，他引：13
介绍“４Ｄ”（即数字地面模型、数字正射影像、数字栅格地图和数字线划地图）系列产品的生产流程、关键技术、及其在耕地保护、防灾减灾救灾和城市规划等方面的应用方法。 相似文献
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《International Journal of Digital Earth》2013,6(1):66-87
Abstract Virtual Australia is not a well-defined or agreed concept. This discussion paper conceptualises Virtual Australia as a ‘virtual [digital] model containing and representing all non-trivial objects and their contextual environment – from blue sky to bedrock – in real world Australia’. It describes a scenario for Virtual Australia, one or two decades from now, in which the locations and conditions of non-trivial objects and their environment are updated automatically through a combination of remote sensing and wireless communication technologies in support of a ‘Supranet’. It then examines the concept of the ‘Supranet’ – a pervasive information network based largely on wireless technology linking the physical world to a virtual model in real time – and develops and discusses three principal characteristics of the Supranet: the ability to have or collect specific information (know); the ability to process information (think); and the ability to communicate that information. If, in the near future, any or all non-trivial devices are to some extent able to know, think and communicate, the potential for object autonomy will be realised. 相似文献
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自动车辆定位导航系统中传感器的误差分析 总被引：1，自引：0，他引：1
对国界定位导航系统中几种常见的辅助传感器所产生的误差进行了分析，导出了不同传感器的误差模型。这些误差模型是估计车辆位置的扩展卡尔曼滤波器的基础，同时也为选择适当的传感器提供了理论根据。 相似文献