1. A three-dimensional measurement apparatus comprising: an outputting unit configured to project a pattern which includes a plurality of lines and in which at least a part of features on the plurality of lines are arranged at unequal intervals from a projection unit to an object; an acquiring unit configured to acquire an image including an object to which the pattern is projected; a detecting unit configured to detect lines and features of the projected pattern from the image acquired by the acquiring unit; an identifying unit configured to identify to which line of the plurality of lines of the pattern each of the features detected by the detecting unit belongs based on positions of the features detected by the detecting unit; and a measuring unit configured to measure a three-dimensional shape of the object to which the pattern is projected based on an identification result of the identifying unit.