17 巻 (1999) 2 号 p. 227-233
The planar positioning of an object using a camera is an important technique for minute manufacturing. And detecting a feature in an image is an essential subject for it, thus research has been actively pursued in this area. Template matching is a useful method of detecting a feature in an image. It doesn't require any complicated settings, and we can use it more easily than other methods (centroid determination in binary image processing, etc.), by an equipment on the market. However, template matching is poor at detecting the rotation of a feature, and the amount of calculation is large. In order to solve these problems, we propose a new method of detecting the translation and rotation of a feature by the use of coarse optical flow. The coarse optical flow is acquired by the differences of the intensity between an objective template and the observed template, and the gradient of the intensity at each pixel in the template. This method is as simple as conventional template matching. Furthermore, it provides sub-pixel accuracy. Then changing the image resolution from coarse to fine makes it possible to reduce the amount of calculation. We show some experimental results of a precise planar positioning.