【作者】 徐生望；

【导师】 朱建军； 左廷英；

【作者基本信息】 中南大学 ， 摄影测量与遥感， 2008， 硕士

【摘要】 目前,坐标系的建立和应用过程中主要出现两方面的问题:首先是地心坐标系已成为目前的发展趋势,而我国的国家坐标系都是参心坐标系。在不同坐标基准间的进行转换时,必须考虑转换参数和椭球参数对高斯平面坐标的影响。其次,我国城市测量规范规定,城市坐标系应满足投影变形不大于2.5cm/km。随着我国城市规模在不断扩大,城市控制网带宽逐渐不足。如何使控制网既满足投影变形和带宽的要求,又兼顾以往的测绘成果,是一个非常棘手的问题。本文主要研究内容如下:(1)通过对两种不同基准间转换的莫洛金斯基模型和WGS-84坐标系和1954北京坐标系两种坐标系下的实例数据分析,研究了转换参数中平移参数、尺度参数和旋转参数变化时平面坐标变化计算的函数模型。通过分析得出以下结论:平移参数对坐标转换的影响较显著:当平移参数变化100m时,对控制点的平面坐标y的影响比x的影响大;y坐标的变化随经度和纬度的增大均增大。尺度参数和旋转参数影响较小,在WGS-84坐标系和1954北京坐标系间转换时,由于转换参数差别较大,故尺度参数影响也较大。对于椭球参数,通过分析推导,得出如下结论:椭球长半径变化与平面坐标x、y的变化存在正比关系;椭球参数中扁率的变化也与平面坐标x、y的变化存在正比关系。长半径变化100m时对平面坐标的影响比扁率变化0.5ppm时的影响要显著得多。长半径和扁率二者同时变化时的影响比单独变化时的影响之和还要显著。(2)城市控制网带宽不足的相关方案、数据处理和实现方法:为了解决控制网带宽不足的问题,本文提出了五种方案:1、由高斯投影变为通用横轴墨卡托投影;2、由高斯投影变为双标准经线投影;3、改变中央子午线,采用高斯投影;4、改变中央子午线,采用非标准的横轴墨卡托投影;5、改变中央子午线,采用双标准经线投影。通过实例分析计算,可得出以下结论:方案1、2的优点是实现简单,缺点是新旧城区控制点坐标变化较大;方案3仍有部分边缘地区投影变形超限。方案4、5的原城区坐标变形很小。综合以上可知:方案4和方案5是切实可行的解决方案。其中,方案5为最佳的解决方案。由于我国处于中纬度地区,这一方案对我国城市是一个较可行的解决方案。本文对以上诸方面作了初步的研究,希望能对实际应用和进一步研究提供一定的实际经验和理论依据。更多还原

【Abstract】 At present, there are two issues in coordinate’s establishment and application: first of all, geocentric coordinate system has become the current trend of development, and all of our national coordinate systems are Reference Centric Coordinate System. Reference Centric Coordinate System will be long-term coexist with Geocentric coordinate system. And then, the Datum Transformation are necessary. In order to resolve this problem, we must consider two Datums’ transformation elements and ellipsoid elements.Secondly, in China’s urban measurement standards, the choice of cities coordinate system should meet the projection and deformation length of less than 2.5 cm / km. As Chinese cities ’ constantly expanding in size , there has a control network bandwidth shortage problem. And the coordinate system should maintain a certain continuity and stability. Therefore, how to meet the demand of projection deformation will be a very difficult issue while takeing into account the previous surveying results.This study follows:(1)By analysising the transformation between two different datums of molodensky model, we study the transformation parameters such as translation parameters,scale parameters or rotation parameters impact on the Gaussian plane coordinates; the ellipsoid parameters such as long radius and flattening impact on the Gaussian plane coordinate. Through above analysis we conclude : translation parameters have more notable effects; When the translation parameters changing 100m, the control points’y coordinates changes larger than x coordinates changes, y coordinates changes are increasing with the increase of latitude and longitude. Parameters of scale or rotation have less effect than the translation parameters, sometimes they can be neglected. Between the WGS-84 coordinates and the 1954 Beijing coordinates’ transformation, the ellipsoid parameters have greatly influence. About the ellipsoid parameters, this paper has a conclusion that long radius and flattening’s change existes proportional relationship with change of plane coordinates x, y. One hundred meters’ change of long radius have more significant impact on plane coordinates than 0.5ppm’s change on flattening. The two aspects’changing at the same time have also more significant impact than separate aspect changing.(2)relevant programmes of city control network bandwidth shortage problem, data processing and implementation:In order to solve city control network bandwidth shortage problems, this paper has five programmes :1, to alter the projection method from Gauss projection to Mecator projection2, to alter the projection method from Gauss projection to a dual-standard longitude projection3, to alter the central meridian, using Gaussian projection4, to alter centric longitude, using non-standard horizontal axis Mecator projection5, to alter the central meridian, using dual-standard longitude projection From the five programmes, we can see that the advantages of the programme 1,2 are to easily achieve. Their disadvantages are what the original urban control points have large change. Programme 3 still have a large distortion at the edge part of urban. Programme 4,5 have a small deformation in the original urban coordinates. So, we can draw a conclusion that programme 4 and programme 5 are practical solutions. Programme 5 is the best solution because of its maintaining conformal projection, meeting projection distortion’s requirements and enabling the old and new urban control point coordinates the smallest change.This paper has a preliminary study on all of above questions.It is my faithly wish that this paper can provide a few of practical experiences or theoretical bases on practical applications and further studies.更多还原