基于数字图像的车辆行驶跑偏在线测量方法

保证车辆在正常情况下沿直线行驶是汽车制造的基本要求,汽车制造厂商高度重视车辆行驶跑偏的检测.文章分析了车辆行驶跑偏量测量的一般方法并提出了一种基于数字图像的汽车行驶跑偏检测方法,实现了车辆行驶跑偏量的自动测量.通过实验,验证了该方法的可行性,且具有自动化程度高、效率高、测量精度高以及可靠性强等特点.基于数字图像的车辆行驶跑偏在线测量系统已投入汽车制造公司的实际生产使用.     

基于NDVI与丰度关系的MODIS影像浒苔混合像元分解方法

MODIS影像是浒苔业务化卫星遥感监测的重要数据源,但其空间分辨率(250m)较低,混合像元效应导致传统的NDVI(Normalized Difference Vegetation Index)阈值法浒苔提取误差较大。为解决此问题,本文以准同步的较高分辨率的HJ-1CCD影像浒苔提取结果为基准,建立基于MODIS NDVI与浒苔像元丰度(浒苔覆盖面积占像元面积百分比)关系的浒苔信息提取模型,利用该模型可提取每个像元的丰度(即浒苔覆盖率),从而提高整景影像浒苔覆盖面积提取精度。该模型可为浒苔灾害等级的确定以及防灾减灾应急决策提供支持。     

Predicting Snow Depth in a Forest–Tundra Landscape using a Conceptual Model Allowing for Snow Redistribution and Constrained by Observations from a Digital Camera

Estimation of snow depth in the forest–tundra landscape remains a challenge because of a lack of reliable and frequent observations on precipitation and snow depth. Snow models forced by gridded meteorological datasets are often the only option available for assessing snow depth at the local scale. Unfortunately, these models generally do not take into account the snow redistribution process between open and forested areas which frequently occurs in the forest–tundra landscape. A simple modification to an existing snow accumulation and melt model is proposed in order to allow for snow redistribution. Along with a technique for taking advantage of snow depth observations obtained from a digital camera, the model is shown to provide accurate predictions of snow depth at the local scale when forced with precipitation data from Environment Canada's Canadian Precipitation Analysis. Results from this study suggest that instrumenting automated weather stations with a digital camera, together with small modifications to an existing model used operationally for snow depth prediction, could result in significant improvements to snow depth prediction and analysis in this environment. Further testing at sites where snow water equivalent of the snowpack is available should, however, be performed to fully validate the method.     

Automatic Identification of Clear-Air Echoes Based on Millimeter-wave Cloud Radar Measurements

Millimeter-wave cloud radar(MMCR) provides the capability of detecting the features of micro particles inside clouds and describing the internal microphysical structure of the clouds. Therefore, MMCR has been widely applied in cloud observations. However, due to the influence of non-meteorological factors such as insects, the cloud observations are often contaminated by non-meteorological echoes in the clear air, known as clear-air echoes. It is of great significance to automatically identify the clear-air echoes in order to extract effective meteorological information from the complex weather background. The characteristics of clear-air echoes are studied here by combining data from four devices: an MMCR, a laser-ceilometer, an L-band radiosonde, and an all-sky camera. In addition, a new algorithm, which includes feature extraction, feature selection, and classification, is proposed to achieve the automatic identification of clear-air echoes. The results show that the recognition algorithm is fairly satisfied in both simple and complex weather conditions.The recognition accuracy can reach up to 95.86% for the simple cases when cloud echoes and clear-air echoes are separate,and 88.38% for the complicated cases when low cloud echoes and clear-air echoes are mixed.     

远距离运动车辆快速跟踪与定位系统设计

为快速跟踪及定位远距离的运动车辆,本文设计了利用单目相机与激光望远测距仪的定位系统。此定位系统装备单目相机、望远测距仪与角度传感器,采用LK光流算法实时跟踪既定目标,构建了相机、测距仪、目标的坐标方程式模型,可实时解算100~300 m外运动目标的位置。该定位系统无需在被测运动车辆上安装任何设施,即可对合作或非合作目标实现跟踪定位。本文以汽车作为运动目标,使用高精度的CORS系统进行精度验证,该系统实时跟踪定位的精度可保持在亚米级。     

二维控制场建立中的关键技术研究

本文对控制点标志的选择进行分析,指出选择的基本原则;提出了基于像点与物方之间几何关系来识别点的方法。阐述了对目标影像的分割、定位及光束法平差解算物方点的空间坐标,并根据验后方差确定观测值的权;给出了一个二维控制场建立的实例,物方控制点的坐标中误差小于±0.2mm。     

基于多片空间后方交会的CCD相机检校

近年来,CCD相机逐步应用于近景摄影测量、低空摄影测量。影响摄影测量成果精度的重要因素之一是相机的技术参数,因此相机技术参数的检校是保证成果质量能否满足精度要求的关键问题之一。文中通过单片空间后方交会和多片空间后方交会的比较试验,分别对两种方法实施了精度分析和可靠性分析,总结得出多片空间后方交会是一种更为可靠的CCD相机检校方法,且运用多片空间前方交会方法进一步验证了多片空间后方交会检校成果的可靠性。     

无人机载线阵摆扫CCD影像几何校正

充分利用无人机载GPS/INS组合导航系统提供的导航遥测数据,首先分析线阵CCD传感器摆扫成像的基础原理和成像特点,并建立严格的成像模型;然后提出线阵摆扫CCD影像严格几何校正的详细算法和流程;最后进行多组实验证实成像模型和几何校正算法的正确性和准确性.实验结果证实采用文中的成像模型和几何校正流程,可获得正确、高精度地理编码的线阵摆扫CCD正射影像.     

地名地址数据快速采集方法的应用创新—以诸城市为例

地名地址数据库作为地名地址数据与地理空间信息挂接的媒介与桥梁,是构成智慧城市地理空间框架不可或缺的组成部分。该文详细对比分析了传统地名地址数据采集方法与RTK+数码相机地名地址数据采集方法的特点。利用RTK+数码相机,在诸城市进行地名地址数据采集,并基于ArcGIS开发一套连接测点和数码相片的"一键关联工具",实现数码相片的影像信息与RTK测点坐标信息关联,为地名地址数据属性编辑服务。为智慧城市建设中的数据采集提供了新的思路,大大减少了地名地址数据采集的工作量,有效提升了地名地址数据的质量,为智慧城市数据库的建立和数据更新提供稳定的数据供应,为其他的外业数据采集项目提供了新的可能性。