Locating and identifying splits and holes on sugi by the laser displacement sensor

Abstract

The split and the hole are two common defects on sugi (Cryptomeria japonica D.Don). They have a common feature in that they are associated with surface irregularities. We have developed a laser scanning system to detect the splits and the holes based on their thickness, which correlates spatially with the profile information. The displacements measured by the laser sensor were converted to pixel values to generate the displacement profile image. Both the splits and the holes manifested well in the image. A dedicated image-processing program written in Visual Basic has been developed. The defects regions were accurately located by the image processing. To identify the defects, eight recognition rules based on four features have been utilized. Furthermore, a method based on the pixel model was proposed to compute the area of the defect. The results indicated that the defects could be identified correctly, and the areas could be computed accurately using the pixels model.

Locating and identifying sound knots and dead knots on sugi by the rule-based color vision system

“…4) by the frame-based method of Otsu. 3,10 To form the complete potential defect areas from the discrete points after segmenting, the 4adjacent connectedness component labeling operation was applied. 11 Rule-based identification of a potential defect region…”

“…To automatically detect wood defects, optical, ultrasonic, microwave, nuclear magnetic resonance, X-ray, and temperature gradient methods have been used. [1][2][3] The optical method has been recognized as a promising technique and some optical systems have been developed to detect wood surface features. Quite recently, the color line scan camera was used to automatically optimize crosscut and to sort red oak edge panel parts.…”

“…In our previous report, we discussed the possibility of using a laser scanning system to detect splits and holes in sugi from thickness information. 3 In this article, we report on a rule-based color vision system that has been developed to detect sound knots and dead knots using color information.…”

Experimental study on quantitative surface defect depth detection based on laser scanning technology in continuous casting

“…It brings some significant advantages: saving energy consumption, improving productivity, reducing product cost, etc. 8,9 Therefore, reliable hot billet surface defect inspection in real time is a significant technology for realising HCR or DCR. In the meantime, if the operation can employ inspection information to feed back to the preceding process, it can be beneficial to find out the original causes generating the billet surface defects; this is essential to control the production process and reduce the defect rate.…”

Experimental study of surface defects in continuous casting using developed laser scanning system

“…The reflected light intensity is measured with a fast response E 3 -CMOS detector, which allows sensor vertical displacement characteristic curves to be recorded. 5 2 Laser CCD displacement measurement schematic representation Laser scan imaging theory and optical structure Geometry of laser CCD displacement measurement system Conventional CCD imaging technology is widespread and well known in many fields: a camera takes colour or grey level images of surface being inspected, which are digitalised and fed to an algorithm that processes the data to highlight the desired parts of the scene (the defects in this case). For this application, conventional imaging by itself is not a reliable solution.…”