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 dot-matrix pattern is used to project a commercially-available low power continuous laser onto the weld pool surface and the reflection of the laser is intercepted by an image plane which is placed with a distance from the arc. While the reflection of the laser travels without reducing much of the intensity, the intensity of the arc radiation decays with the distance rapidly. To utilize the reflection to reconstruct the weld pool surface, the correspondence of the reflection points with their projection points must be found. This paper addresses the algorithms to extract the reflection points from the image and then match the reflection points with their projection points. The establishment of the correspondence provides the data needed to reconstruct the weld pool surface based on the reflection law.