基于N元正弦码元的时间相位展开  

Temporal Phase Unwrapping Based on N-Ary Sinusoidal Codewords

作　　者：安海华 曹益平[1] 王丽丹[1] 杨钠 An Haihua;Cao Yiping;Wang Lidan;Yang Na(College of Electronics and Information Engineering,Sichuan University,Chengdu 610065,Sichuan,China)

机构地区：[1]四川大学电子信息学院,四川成都610065

出　　处：《光学学报》2023年第2期80-89,共10页Acta Optica Sinica

基　　金：国家科技重大专项(2009ZX02204-008)。

摘　　要：提出了一种N元编码时间相位展开方法来实现彩色复杂物体的三维测量。传统的阶梯状条纹在测量整个表面反射率范围较大的物体时,条纹数量过多会导致量化困难。利用从相移条纹中提取的N元正弦码元替换传统的量化灰度码元,通过进制转换将N元正弦码元嵌入到所要投影的条纹中来实现条纹级次的编码。在解码时,先通过编码条纹与N步正弦相移条纹的差异逐点计算N元量化条纹,再根据对应的逆进制转换获取唯一的条纹级次,最后利用截断相位消除条纹级次边缘处的错位误差。实验结果表明,相比传统的时间相位展开方法,所提方法有效提高了编码效率,并在测量彩色复杂场景时表现出了较高的鲁棒性。Objective Phase-shifting profilometry(PSP)has been widely used in various three-dimensional(3D)scenes due to its high accuracy and robustness.In fringe projection profilometry(FPP),unwrapping the phase map in(-π,π]is an inevitable consideration.Phase unwrapping algorithms are commonly divided into two types:spatial phase unwrapping algorithms(SPUAs)and temporal phase unwrapping algorithms(TPUAs).Conventionally,TPUAs are more suitable for measuring discontinuous objects as they can identify fringe orders pixel by pixel.TPUAs are also employed in real-time3D measurement because of the development of hardware and defocusing systems.Numerous TPUAs have developed at a fast pace in the past few decades,mainly including multi-frequency,intensity-code,and phase-code ones.Multi-frequency methods suffer the low accuracy of the low-frequency patterns and the complicated selection among different frequencies.Intensity-code methods,mainly N-ary Gray codes with concision and high efficiency,directly use intensity information to generate the fringe order map,but they can barely measure colorful objects.In phase-code methods,massive codewords are coded into the phase domain with a depth of only 2π,and the difference between adjacent quantized phases may be too small to ensure the correct decoded codewords for a large number of fringe orders.Essentially,the proposed sinusoidal codewords are directly extracted from N-step phase-shifting patterns to replace additional stair-shaped codewords in intensity-code and phase-code methods.By contrast,the proposed fringe-order encoding method based on N-ary sinusoidal codewords performs outstanding coding flexibility and efficiency while breaking through the limitations of the number of fringe orders in phase-code methods and overcoming the sensitivity to reflectivity in Gray-code methods.Methods A temporal phase unwrapping method based on N-ary coding is proposed to realize the 3D measurement of colorfully complex objects.When measuring an object with a large range of overall surface re

关 键 词：测量 条纹投影 时间相位展开 条纹级次 N元编码 

分 类 号：TN247[电子电信—物理电子学]