Patent ID: 7274802

Claim:
An automatic tracking apparatus for a reflector comprising: a surveying machine body; an illumination portion disposed in said surveying machine body for illuminating a measurement light toward a reflector; a light receiving portion which is disposed in said surveying machine body and which has an image sensor for receiving a reflection light image of the measurement light illuminated toward said reflector; an arithmetic portion for calculating a position of the reflection light image from said reflector in an area of said image sensor based on a received light of said image sensor; a rotation mechanism for rotating said surveying machine body in horizontal and vertical directions so as to position said reflector on a light receiving optical axis of said light receiving portion based on the position obtained by said arithmetic portion; a storing portion for storing a quantity of light at each pixel in said image sensor; and an edge position detecting portion for detecting a beginning edge position and an end edge position of said reflection light image at each scanning line in said image sensor, wherein said automatic tracking apparatus reads out the quantity of light at each pixel from said storing portion, and obtains a width between said beginning edge position and said end edge position at each scanning line after calling out the positions from said edge position detecting portion, and decides the scanning line corresponding to the widest line as the position of the weighted average in the horizontal direction, and calculates the position of the weighted average in the vertical direction of the reflection light image based on the quantity of light of the pixel which exists between said beginning edge position and said end edge position in the scanning line corresponding to the widest line.