基于彩色结构光的动态线扫描形貌测量方法

Dynamic Line-Scan Profile Measurement Method Based on Color-Encoded Structure Light

以高铁、铁轨为代表的延展性表面测量逐步向智能化发展,要求在线测量,同时兼顾效率和精度,对动态性能提出了新的挑战。基于线阵相机条纹投影的三维形貌测量方法兼具高分辨率与高速采集,具有延展表面三维重建领域的高动态性理论优势,但鲁棒性较强的条纹投影测量方法需要多帧测量获得准确相位,编码效率低,因此减小测量周期、减少图像帧数仍是提升动态性能的迫切问题。研究基于三频彩色条纹投影的双线阵延展表面测量方法,使用彩色条纹投影减少投影帧数,并利用纯色图补偿法降低通道串扰。先后对被测物体投影一幅彩色编码正弦条纹图和一幅白图,引入一维背景归一化方法降低被测物表面光学性质的影响,基于彩色编码信息获取展开相位并根据同名相位匹配双线阵相机。所提方法有效发挥线扫描的动态优势,仅通过两帧投影就实现运动中高质量点云的获取,同时实现纹理映射。

The advancement of intelligent,extendable surface measurement,exemplified by high-speed railway and track detection,necessitates improvements in on-line measurement,efficiency,and accuracy.This requirement presents a new challenge to dynamic performance.Multiframe measurement methods using stereoscopic line-scan camera systems facilitates high-resolution and high-speed data acquisition.Similarly,the three-dimensional shape measurement method,which employs fringe projection with line-scan cameras,facilitates high-resolution and rapid data collection.These methods are advantageous for achieving high-quality three-dimensional reconstruction of extendable surfaces in motion.However,a robust fringe projection measurement method requires multiple frames to obtain accurate phase information,leading to low encoding efficiency.Thus,reducing the measurement period and decreasing the number of required image frames remain critical issues for enhancing dynamic performance.To mitigate these challenges,we introduced a dynamic measurement method for extendable surfaces using stereoscopic line-scan cameras and color-encoded three-frequency-fringe projection.We employed composite stripe projection based on color-structured light to minimize the number of projected patterns and three solid color images for effective crosstalk compensation.We sequentially projected a color-encoded sine fringe and white patterns onto the object,incorporating one-dimensional background normalization to mitigate the influence of the object's surface optical properties.This enables the acquisition of unwrapped phases based on color encoding information.Pixels in the images obtained from both cameras that share identical unwrapped phases are identified as corresponding pixels.The proposed method effectively exploits the dynamic capabilities of line-scan technology,thus achieving high-quality contour mapping through two frames and facilitating texture mapping.