Three dimensional measurement apparatus and three dimensional measurement method

A three dimensional measurement method by a three dimensional measurement apparatus, the apparatus comprising:

• a projection unit that projects, to a measurement target object, a first pattern light including alternately arranged bright parts and dark parts and a second pattern light in which a phase of the first pattern light is shifted;
• and
• an imaging unit that images the measurement target object on which the first or second pattern light is projected, the method comprising:
• a first acquisition step by a first acquisition unit acquiring first image data by causing said projection unit to project the first pattern light to cause said imaging unit to image the measurement target object;
• a second acquisition step by a second acquisition unit acquiring second image data by causing said projection unit to project the second pattern light to cause said imaging unit to image the measurement target object;
• and
• a calculation step by a calculation unit calculating a three dimensional position by calculating intersection positions of tone values of the first pattern light in the first image data and tone values of the second pattern light in the second image data, wherein
• in said first and second acquisition steps, when a period of repetitions of the bright parts and the dark parts of the first or second pattern light is one period, a range of imaging on the measurement target object by one pixel included in said imaging unit is an image distance, and the length of one period of the projected first pattern light or second pattern light on the measurement target object surface is M times the image distance, said projection unit and said imaging unit are arranged to satisfy
• 2×N−0.2≦M≦2×N+0.2,
• where N is an integer value equal to or greater than 2.