Shape measuring device, shape measuring method, and glass plate manufacturing method

A shape measuring method comprising the steps of:

• by using an image pick-up section arranged such that an optical axis becomes perpendicular to a direction of extending of a linear pattern arranged above a transparent flat plate serving as a measurement object, capturing an image of two reflection spot groups of the pattern generated by a first surface and a second surface of the transparent flat plate and thereby generates an image containing two reflection images separated in a direction perpendicular to the direction of extending;
• estimating from the image a first surface reflection spot group of the pattern in the first surface of the transparent flat plate by using a positional relation of the transparent flat plate, the pattern, and the image pick-up section;
• calculating an inclination angle of the first surface of the transparent flat plate at a position of the estimated first surface reflection spot group by using the positional relation of the transparent flat plate, the pattern, and the image pick-up section;
• and
• determining a shape of the first surface of the transparent flat plate based on the calculated inclination angle.