Three-dimensional measurement apparatus

A three-dimensional measurement apparatus comprising:

• an illumination device that irradiates a measurement object with a first and a second light pattern each having a fringe-like light intensity distribution;
• a camera that takes image data of the measurement object irradiated with the first and the second light pattern;
• a motor that displaces a position of the measurement object with respect to the camera;
• and
• a processor that:
• three-dimensionally measures the measurement object based on the image data,
• obtains a first measurement value of the measurement object per pixel based on a first predetermined number of image data taken with the first light pattern at a first predetermined number of phases at a first position,
• obtains at least one of a gain value and an offset value per pixel based on the first predetermined number of image data,
• obtains a second measurement value of the measurement object per pixel based on:
• the one of the gain value and the offset value, and
• a second predetermined number of image data taken with the second light pattern at a second predetermined number of phases at a second position shifted by a half of a pixel in a predetermined direction from the first position, wherein the second predetermined number is smaller than the first predetermined number,
• obtains height data of the measurement object per pixel based on the first and the second measurement value, and
• obtains the second measurement value per pixel by using an average of the one of the gain value and the offset value of pixels adjacent to each pixel of the image data.