In-process surface profile assessment of rotary machined timber using a dynamic photometric stereo technique

Abstract

Machining operations have advanced in speed and there is an increasing demand for higher quality surface finish. It is therefore necessary to develop real-time surface inspection techniques which will provide sensory information for controlling the machining processes. This paper describes a practical method for real-time analysis of planed wood using the photometric stereo technique. Earlier research has shown that the technique is very effective in assessing surface waviness on static wood samples. In this paper, the photometric stereo method is extended to real industrial applications where samples are subjected to rapid movements. Surface profiles extracted from the dynamic photometric stereo method are compared with those from the static measurements and the results show that there is a high correlation between the two methods.

Metal forming beyond shaping: Predicting and setting product properties

“…As a result of using laser light in combination with fast data processing, this method is useable for an in-situ measurement. The same applies to the photometric technique [157]. In contrast, near field scanning optical microscopy, with a lateral resolution better than 80 nm [191] is, based on its elaborated test setup, only useable offline [112].…”

“…Table 2 summarizes [157] X X X Laser triangulation [198] X X X Electronic speckle pattern interferometry [94,165] X X X Near field scanning optical microscopy [94,191] X X [34,111] X X Hardness measuring [214] X X X X Creep rupture test [135] X X Shear test [32] X X Plane torsion test [170,230] X X X Impact test [39,204] X X X-ray diffraction [77,99] X X X X Magneto-inductive testing [42] X X X Defects (cracks) and damage voids)…”

Real-Time 3D Shape of Micro-Details

“…As it is shown by Woodham [67], the orientation of a Lambertian surface can be uniquely determined when at least three input images are given. During last decades, PS has attracted wide attention in different practical domains such as industrial quality control [11,74,42,25], face recognition [72,75,14,73], Figure 1. A successful 3D reconstruction from very fine details of micro-prints on a 50 euro banknote shown in gray color rectangular parts of (A) and (B).…”

An active three-dimensional vision system for automated detection and measurement of surface defects

“…The PS technique is not new in the field of computer vision, 4 but advancements in machine vision technology have extended its application domain to include industrial inspection tasks. Typical existing applications of the PS method reported in the literature include inspection of ceramic tiles, 5 wood 6,7 and planar steel. 8 However, the existing applications are all are focused on 3D shape reconstruction only.…”