METHOD AND APPARATUS FOR FOLLOWING AND INSPECTING AN EDGE OR BORDER

To follow and inspect a common edge between two sheet metal blanks which are to be welded together, a line pattern is projected across the edge by a projector and is imaged by a camera. The image captured is analyzed in order to derive from the trace of the lines information on the gap between the blanks, or on the track of the edge. The pattern projected has several lines with different light intensities. When the photographed image is processed, it is then possible—even if there is variation in the reflection characteristics of the sheet metal blanks—to select a line which is neither too faint nor too bright in the image obtained and which can therefore be used for meaningful analysis.