A new effective method on critical point detection of planar curves

Abstract

平面曲线的关键点检测可用于数字曲线的直线段逼近 ,因此在很多图像识别、测量及分析的场合均有重要应用 .由于一般的数字直线均为若干连续的水平、垂直、± 4 5°夹角直线段合成 ,称之为四个基本方向 ,并将每个基本方向的最大直线段长度定义为其方向象素长度 (directionalpixellength ,DPL) .提出了四个定理 ,证明了在相互垂直方向上的DPL不会同时超过 1个象素 ,而 4 5°夹角方向上DPL不会同时超过 2个象素 .在此基础上 ,提出并设计了一种全自动关键点检测算法 .通过和现有典型算法的实验对比 , 验证了该方法在减少关键点数和时空开销方面的显著优势. Critical point detection (CPD) of planar curves can be well applied in approaching of curves using poly lines,which has very important applications in image recognition,measurement and analysis.As digital lines are commonly composed by several continuous short lines,which are horizontal (k is 0),vertical (k is 1) and ±45°(k is ±1) lines.We call these four lines basic lines and define the maximum length of every basic line as corresponded directional pixel length (DPL),which are further denoted as Lx,Ly,L+ and L .Furthermore,four theorems on DPL are proposed,based on which,an automatic algorithm for CPD is also presented.The comparisons of algorithms from Ansari Huang,Zhu Chirlian and ours was showed.The satisfactory experimental results have demonstrated that our algorithm has apparent advantages in reducing critical point number and spatial temporal spending.