Laser stripe extraction in additive manufacturing based on spatiotemporal noise regularization
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Laser stripe extraction in additive manufacturing based on spatiotemporal noise regularization Haotian Yu1,2 · Chongchong Peng1,2 · Zhuang Zhao1,2 · Yi Zhang1,2 Received: 5 May 2019 / Accepted: 27 September 2020 © The Optical Society of Japan 2020
Abstract The optical three-dimensional (3D) measurement technique based on the laser stripe has become increasingly important in additive manufacturing, which is necessary to extract the laser stripe accurately. In welding, the wrong laser stripe centers due to the high-brightness noise are usually extracted, which causes serious measurement error. In this paper, a laser stripe extraction algorithm based on spatiotemporal noise regularization (SNR) is proposed, which calculates the noise weight of each pixel in time dimension and suppresses the high-brightness noise in space dimension. The proposed algorithm contains four novel steps to achieve accurate and fast laser stripe extraction when the laser stripe is influenced by the high-brightness noise. Meanwhile, an online welding 3D measurement system is constructed based on double-line structured light, which can achieve online 3D measurement in additive manufacturing. Experimental analysis verifies its effectiveness and accurateness. Keywords Laser stripe extraction · Spatiotemporal noise regularization · Additive manufacturing · 3D measurement
1 Introduction Recently, with the development of intelligent welding, threedimensional (3D) data have gradually become important. Due to the advantages of accuracy and speed, optical 3D measurement techniques have been widely used in welding [1–4] and other industrial applications [5–10], which can be classified as passive and active. The passive techniques use two cameras or more to capture the images of the measured object, and the 3D data can be obtained by stereo matching [11]. The active techniques use a structured light and * Yi Zhang [email protected] Haotian Yu [email protected] Chongchong Peng [email protected] Zhuang Zhao [email protected] 1
Jiangsu Key Laboratory of Spectral Imaging and Intelligent Sense, Nanjing University of Science and Technology, Nanjing, China
School of Electronic and Optical Engineering, Nanjing University of Science and Technology, No. 200 Xiaolingwei Street, Nanjing 210094, Jiangsu Province, China
2
a camera to achieve the 3D measurement, which are more common because of the higher accuracy compared with the passive techniques [12]. However, in the complex environment, the active techniques maybe suffer from robustness problems, which are difficult to obtain reliable 3D data [13]. In welding, the active technique based on the laser stripe system is usually used. The system projects a laser stripe on the measured object, which can be captured by a camera, and the 3D data can be calculated. Thus, laser stripe extraction is the basic and important procedure for 3D measurement. In general, the laser stripe extraction algorithms are mainly divided into three categories. The first category is based on geometr
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