Measurement of concrete crack feature with android smartphone APP based on digital image processing techniques. (January 2020) - Ni, Tongyuan
Highlights: An new non-contact measurement of concrete cracks was introduced in this paper. An new test method for concrete crack based on smartphone APP was studied. The single pixel point size of smartphone camera's CMOS was investigated. The accuracy of APP measurement method can be meted to the requirements of detection. Abstract: Detection and analysis of concrete cracks feature are important aspects of concrete crack research, and non-contact measurement of concrete cracks is an important research direction. In this paper, measurement and analysis of concrete crack feature based on smartphone APP of digital image processing techniques (SADIPT) in android system was investigated. The results showed that the size of single pixel point (SSPP, η ) has a good linear relationship with the shooting distance in basic lens under no amplification. The relations between all kinds zoom lens of smartphone and the shooting distance followed the exponential function law. The SSPP of zoom lens ( η ' ) can be calculated with an exponential function, and it was determined by smartphone's camera's CMOS (complementary metal oxide semiconductor) performance, and the magnification of zoom lens can effectively improve the measurement accuracy. The η ' function curves of the same maximum magnification ratio with same basic pixel were slightly different for different smartphone camera's CMOS while the influence of basic pixel of smartphone zoom lens on η ' was significant. The SSPP η ' under non-amplification mode decreased as the base pixel increased, but it's not linear. The results showed that the relations between SSPP η ' of all zoom lens and amplification ratio followed the exponential function law at same shooting distance. The accuracy of measuring concrete cracks with smartphone zoom lens or shortening the shooting distance can meet the requirements of engineering detection.