低空无人飞艇航测相机稳定平台控制方法

针对低空无人飞艇航空遥感系统平台姿态稳定问题,以及现有稳定平台用于无人飞艇航测系统存在的困难,提出了基于轻小型低精度GNSS/IMU系统和PID算法的三轴稳定平台控制方法。该系统结合双GPS轻小型组合GNSS/IMU系统,采用分离相机和GNSS/IMU系统控制方式,采用PID控制方法,利用STM32控制芯片电路实现稳定平台的控制,解决无人飞艇航测系统相机姿态稳定问题。最后通过飞行试验验证了该系统的稳定性。试验结果表明,该方法能够满足相机系统的俯仰和翻滚角度及航偏角度控制的要求,能够有效隔离无人飞艇姿态的不稳定对成像系统的影响,对于提高无人飞艇航测系统成图精度有重要意义。     

A four lens camera design

A camera design with only four lens elements gives good imaging performance at a working focal ratio of f/4.4.     

数字摄影测量相机的畸变测量与纠正

在研究数字相机畸变误差来源和测量原理的基础上,设计出基于光学测角法原理的数字相机畸变测量装置。对目前常用10参数畸变纠正模型进行理论分析,并提出畸变纠正精度评价方法。最后进行了畸变测量和纠正实验。结果表明,畸变纠正精度优于0.002mm,满足相关标准的要求。     

论不同航天摄影测量传感器的摄影测量性能

介绍了光学框幅相机胶片摄影、光学相机CCD线阵摄影、微波雷达成像的摄影测量现状以及各自的摄影测量性能与特点。     

数字近景摄影测量系统PV-1的几何精度

本文系统地介绍了所建立的一个数字近景摄影测量系统PV—1的检校方法,并得出了该系统的点定位精度。初步实验表明。运用直接线性变换法进行点定位精度评定,物方坐标的中误差为:M_x=0.247mm,M_y=0.158mm,M_z=0.272mm,象方坐标的中误差为0.2像元,相对精度为1/6000。     

Using an unbaited stationary video system to investigate the behaviour and interactions of bull sharks Carcharhinus leucas under an aquaculture farm

Bull sharks Carcharhinus leucas are common along the coast of Reunion Island (South-West Indian Ocean) and were suspected to aggregate in the vicinity of an aquaculture farm in Saint-Paul Bay on the west coast. In order to understand the behaviour and interaction of bull sharks near aquaculture cages at Saint-Paul Bay, we deployed an experimental unbaited stationary video camera. From 175 hours of recording during daylight hours from March to April 2012, eight individual female bull sharks (seven adults and one immature) were identified based on their natural markings. These sharks were resighted between 3 and 45 times. Residency analysis revealed site attachment under the aquaculture cages for at least three individuals over the course of the study. Recorded behaviours included intraspecific social interactions such as synchronised swimming. Social interactions and relatively strong paired associations for two pairs of females suggest some level of sociality among bull sharks around Reunion Island. Overall, our results demonstrate the utility of unbaited video systems to monitor the behaviour of adult coastal sharks.     

Digital astro-geodetic camera system for the measurement of the deflections of the vertical: tests and results

This study introduces the new results of a novel low-cost digital zenith camera system operated in Turkey that uses astronomical and geodetic instrumentation. Currently, it is possible to determine deflections of the vertical (DoV) components by using a vast amount of information gathered from geo-referenced star images, tilt measurements, and Global Navigation Satellite System technology. This new design of an astro-geodetic camera system is used for calculating DoV components with 12 independent solutions on a test station in Istanbul, and additional observations were performed to investigate the external accuracy of the system on a test network. A specific leveling method is developed to align system toward the zenithal direction. The final results of the observations on a test station located in Istanbul indicate that the accuracy of the system is about ±0.19 arc-seconds in latitude and ±0.28 arc-seconds in longitude determination. The system has been further tested on a network with 4 control points that have averagely 20?km baselines. At the test network, the root mean square of the average value of the vertical deflections is calculated as ±0.36 arc-seconds. Furthermore, DoV components are compared with the values that are calculated using global geopotential models.     

基于黑白环扇圆盘的角点自动识别与排序

采用传统棋盘格进行相机标定时,标定模板旋转角度对角点排序带来较大的影响,针对此设计了一种黑白环扇圆盘标定模板,并提出了与该标定模板相应的角点识别和排序算法。新的标定模板设计中心圆为1/4缺口的黑色圆,以此来消除标定模板旋转给角点排序带来的影响。通过模板区域分割算法实现标定模板的提取;创建圆形检测器剔除Harris算法提取的伪角点;利用向量积和角点几何特性完成角点排序。实验结果表明:该标定模板及其角点识别与排序算法可以有效剔除伪角点,角点排序具有良好的旋转不变性,能够实现自动相机标定。     

飞思IQ180相机的组合相机设计与分析

针对当前大多UAV搭载单个数码相机进行摄影测量时存在的实际问题,详细分析了多面阵组合相机的结构设计。以飞思IQ180相机为例,通过比较双拼组合相机与三拼组合相机的组合方式及各自成像特点,对其相机的组合参数以及相应关系进行探讨;并通过对拼接误差与高程精度的影响分析,得出组合相机对高程精度的提高、增大像幅、提高作业效率等方面有明显的优越性,对多面阵数码相机的设计具有一定的指导意义。     

2.5维电子地图渲染成图接边方法探讨

2.5维电子地图与二维、三维矢量地图有着明显区别,其分批渲染成果是栅格数据,最后成果也是图像的形式,所以在地图接边的方式上比矢量图接边的方法要复杂得多。本文探讨了一种方法,使用虚拟相机确定2.5维电子地图俯瞰视角,制作批量渲染成图的接边参考框架,最后分批渲染景观模型与框架进行图像叠合。这种方法在项目实践中初见成效,能最大限度地缩小接边误差,不足之处是人工干预部分较多,必然导致误差累积,有待改进。