A new pixel matching method using the modulation of shadow areas in online 3D measurement

• The modulation information of the measured object is calculated for matching pixels.
• The shadow areas having low modulation degree are used in this method.
• The Otsu method and the binarization are used to deal with the modulation patterns.
• This method can improve the speed of matching pixels with the accuracy guaranteed.

A new pixel matching method based on phase measuring profilometry (PMP) using the modulation of shadow areas in online 3D measurement is proposed and verified by experiments. The modulation of the shadow areas representing low reliability of the phase of the object which is usually avoided as much as possible is now used to match pixels of the measured object on pipe-line as the reason for its distinguished feature in this paper. In this method based on the modulation of shadow areas, we use the Otsu method to find out a threshold value and then use it to realize the binarization for the modulation image of the object extracted from the deformed fringes. As there are only 0 and 1 in the binarization image so that the calculation is fast as the product of 0 and anther nonzero number is 0, the speed of pixel matching can be promoted with the precision guaranteed. With more complex objects, the saved time will be more. The experiments prove it.