Real-time Coaxial 3D measurement using depth from projection defocus

我们开发了基于深度相关调制传递函数的运动条纹投影单帧三维测量系统。当具有一定空间频率分量的条纹图案在物体上运动时，其上的亮度具有时间变化，这是由其速度和空间频率决定的。由于投影透镜的低通滤波特性，该时间变化的幅度随着距焦点的距离的增加而逐渐减小。相关图像传感器可以在单帧图像中捕捉物体的时间变化，从而重建物体的三维形状。我们已经通过一些实验证实了这些原理。

We have developed single frame 3D measurement system using moving stripe pattern projection based on depth dependant modulation transfer function. When the stripe pattern with a certain spatial frequency component moves on the object, the brightness on it has temporal variation which is determined by its velocity and spatial frequency. The amplitude of that temporal variation decreases gradually with an increase in distance from focal point because of low-pass filter characteristics of the projection lens. The correlation image sensor can captures temporal variation in single frame, so that the 3D shape was reconstructed. We have confirmed those principles by some experiments.