Abstract
Digital speckle correlation method is widely used in the areas of three-dimensional deformation and morphology measurement. It has the advantages of non-contact, high precision, and strong stability. However, it is very complex to be carried out with low speed software implementation. Here, an improved full pixel search algorithm based on the normalized cross correlation (NCC) method considering hardware implementation is proposed. According to the field programmable gate array (FPGA) simulation results, the speed of hardware design proposed in this paper is 2000 faster than that of software in single point matching, and 600 times faster than software in multi-point matching. The speed of the presented algorithm shows an increasing trend with the increase of the template size when performing multipoint matching.
Highlights
With the rapid development of advanced manufacturing technology, the research of three-dimensional measurement technology is widely used in the fields of material testing, strength testing, and quality control
The digital speckle correlation method breaks the limitations of traditional measurement methods and creates a wide range of applications, such as the measurement of deformation of composite materials [5], the detection of cancer cells by measuring the skin strain [6], and measurement in a complex and severe environment [7,8,9,10], et al The basic idea of digital speckle correlation method is to divide the search process into two parts, the full-pixel search and the sub-pixel search [11]
The size of the reference sub-area is an important factor affecting the accuracy of the entire pixel search
Summary
With the rapid development of advanced manufacturing technology, the research of three-dimensional measurement technology is widely used in the fields of material testing, strength testing, and quality control. Compared with other optical measurement methods, the most significant advantage lies in its simple experimental equipment and convenient measurement It has the characteristics of full field non-contact, no damage, high accuracy, and high automation by using binocular image acquisition equipment [2,3,4]. Because of these characteristics, the digital speckle correlation method breaks the limitations of traditional measurement methods and creates a wide range of applications, such as the measurement of deformation of composite materials [5], the detection of cancer cells by measuring the skin strain [6], and measurement in a complex and severe environment [7,8,9,10], et al. The basic idea of digital speckle correlation method is to divide the search process into two parts, the full-pixel search and the sub-pixel search [11]. The low speed during the Electronics 2018, 7, 428; doi:10.3390/electronics7120428 www.mdpi.com/journal/electronics
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