基于反向映射法逆向描述数字散斑变形的方法

考虑 到现有制备模拟散斑图方法系统误差较大、生成方法复杂和编程实现困难等不足,提出 一种基于反向 映射法的变形散斑图生成方法,将变形模式进行反向变换,并利用变形过程中图像灰 度不变的特性, 生成变形后的模拟散斑图。仿真分析表明对于相同数字图像相关(DIC)法计算参数,本文的 反向映射法生成的变形散斑图具有更高 的计算精度,因而提高了DIC法计算结果的可信度；并且,本文的反向映射法具有易于理 解和易编程实现等优点。

Reverse mapping for generating simulated deformed speckle patterns

Digital image correlation (DIC) technology is an optical method which is developed to measure the deformation characteristics of the specimen surface in experimental mechanics.U sually there are all kinds of factors affecting the calculation of digital image correlation method.In order to study the affecting factors, simulated speckle patterns with controlled deformation are applied on DIC calcul ation accuracy analysis.However, existing methods for generating simulated speckle images have some deficiencies, such as introducing systematic error,complex algorithm,and being hard to realize by programming.A novel reve rse mapping based method is proposed in this paper to generate simulated speckles.This new method assumes t hat point coordinates of the deformation speckle image are already known.Then the point coordinates of the s peckle image before deformation can be gotten by reversely transforming the deformation mode.Based on image int ensity invariance during the deformation and the already generated speckle image before deformation,this new method extracts the intensity values of the image before deformation to generate the speckles after deformatio n.The simulation analyses validate that,with the same DIC calculation parameters,speckles generated by r everse mapping method present higher calculation accuracy.And this new algorithm is easy to understand and re alize.