Image processing for measurement of three-dimensional GTA weld pool surface

Observing and measuring the weld pool surface is a key to developing next-generation intelligent welding machines and to understanding the welding process better. In this paper, a dotmatrix pattern is used to project a commercially available low-power continuous laser onto the weld pool surface. The reflected laser beam is intercepted by an image plane, which is placed at a distance from the arc. While the reflection of the laser travels without reducing much of the intensity, the intensity of the arc radiation rapidly decays with the distance. To utilize the reflection to reconstruct the weld pool surface, the correspondence of the reflection points with their projected points must be found. This paper addresses the algorithms used to extract the reflected points from the image and then match the reflected points with their projected points. The establishment of the correspondence provides the data needed to reconstruct the weld pool surface based on the reflection law.