基于AUTO CAD的自动跟踪扫描矢量化系统的设计

【作者】 易辉伟；

【导师】 邹峥嵘；

【作者基本信息】 中南大学 ， 大地测量学与测量工程， 2004， 硕士

【摘要】 在建立GIS的过程中，获取精确可靠的地理空间数据对建立地理信息系统的数据库非常重要。地理数据的获取不仅是GIS的重要组成部分，而且已成为制约GIS发展的一个瓶颈。目前，人们大多使用扫描矢量化软件对原有地形图进行数字化建立基础地理数据库。本文针对现有扫描矢量化软件中采取逐线手工跟踪的不足，如速度慢、精度低、容易出错等，而全自动识别矢量化软件尚未成熟的现状，设计一个自动跟踪扫描矢量化系统。 本文在论述一般性的图象预处理，如二值化、加粗、定向与纠正以及细化等的基础上，提出采用活动矩形方法在线条尾端点处进行判断，使断裂线能够自动连接，从而实现线条的完整跟踪。在数据压缩方面运用逐点筛选法，以有效提取曲线特征点。为充分利用AUTO CAD的现有功能，作者用VB在AUTO CAD上开发了该系统，基本达到预计的效果，适合于地形图的矢量化更多还原

【Abstract】 The acquisition of precise geographical space data is essential to building the data base of GIS,ie,it is not only the vital part of constructing GIS,but also the bottleneck of GIS development .Generally,Vectorizing systems are utilized for digitizing existing topographic maps in order to build the data base of GIS.A new vectorizing system with automated tracing functions is developed for solving the problems such as low speed,poor precisition and fallibility in the manual tracing systems,and low accuracy in the automated vectorizing systems.Based upon general preliminary processing of raster images,such as converting the images to grey scale of 0 or 1,broadening of lines,orientating ..correcting and thinning,etc. a method of mobile rectangle is used to determine whether one line links up with another well or not,which results in connection of the fractured segments and ,therefore,perfect tracing of lines is achieved.Whatsmore,a new method ,selection from point to point,was put forward for data compression and extraction of characteristic points in the curves. The proposed methods are performed under the enviroment of AUTO CAD with visual Basic language and it is suitable for vectorizing topographic maps.更多还原