基于精确坐标控制的背向照明图像拼接方法研究

Study on Mosaic Method for Backlighting Images Based on Accurate Location Control

针对叶型孔四轴影像测量系统中的成像视场局限问题,提出了一种基于精确坐标控制的背向照明图像拼接方法,以用于将采集到的多幅叶型孔局部图像拼接成全局图像。建立了该方法的数学模型,通过实际平移距离与像素尺寸当量等相关硬件参数反求得到图像拼接矩阵,而后采用刚性变换实现局部图像之间的逐次拼接。该方法包括局部图像数量计算、局部图像采集、图像拼接矩阵解算和全局背向照明图像生成等步骤,具有计算简单、运算量小、不涉及图像信息且无需图像重叠等优点。为了验证所提出的图像拼接方法的功能实现,应用该测量系统对分布于某静子环试验件上的目标叶型孔特征进行了图像拼接与测量实践,获取到其全局图像和型面轮廓参数测量结果,从而验证了叶型孔背向照明图像拼接方法的可行性和有效性。

As to the imaging filed limitations of the vision measuring system for blade-shaped holes,an image mosaic method based on accurate coordinate control was proposed to derive the panoramic image through the local backlighting images.The mathematical model was established to realize successive mosaic procedure of the adjacent local images through rigid transformation,in which the mosaic matrixes were computed by the related hardware parameters such as actual translation distance and equivalent size of pixel,etc.The method consists of calculation of the number of local images,capture of local images,computation of mosaic matrixes and generation of panoramic backlighting image of the blade-shaped hole,etc.Moreover,taking no account of the image information and overlap,the method possesses simple and low computation in image mosaic.To verify the function realization of the image mosaic method,a test piece of stator outer ring was selected as the target and the blade-shaped hole distributed on it was measured by the system to derive its panoramic image and profile data,which manifested the feasibility and effectiveness of the mosaic method for backlighting images.