Line-encoded structured light measurement method in measuring shiny and transparent objects

Structured light measurement (SLM) has been widely used in acquiring the three-dimensional (3D) shape of objects because of its high precision and high speed. However, the intensity based structured light coding strategies like sinusoidal patterns is difficult to measure transparent and shiny objects with high dynamic range surface reflectance due to inaccurate light intensity information. Divergent multi-line structured light projection and traditional gray-code method avoids this problem by extracting lines. However, traditional gray-code method requires additional many patterns to distinguish the order of lines, which reduces the measurement efficiency. To overcome defects, this paper proposes a line-encoded few-pattern SLM method in measuring shiny and transparent objects. In this method, we simultaneously extract the edge line, the center line and obtain their orders by projecting only five patterns. Many experiments were implemented to prove its accuracy and robustness. Because only five patterns are required, the proposed method greatly accelerate the process of reconstruction, which is indispensable for 3D real-time reconstruction. We conducted a dental model dynamic scanning experiment to prove it.