1. A measurement apparatus for measuring relative position or orientation of an image-capturing apparatus configured to capture images of one or more measurement objects with respect to a measurement object, wherein the measurement apparatus comprises: an image acquiring unit configured to acquire a captured image from the image-capturing apparatus; a projection unit configured to project geometric features of a 3D model of the measurement object onto the captured image based on a position and orientation of the image-capturing apparatus to obtain projection geometric features; a sort unit configured to sort the projection geometric features of the measurement object obtained by the projection unit into an order effectively of the projection geometric features for calculating the relative position or orientation of the image-capturing apparatus; a detection unit configured to detect image geometric features from the captured image, by searching image geometric features corresponding to the sorted projection geometric features detected in the captured image by the sorted order wherein the searching can be interrupt; and a calculating unit configured to calculate the relative position or orientation of the image-capturing apparatus with respect to the measurement object using the sorted projection geometric features and the detected image geometric features corresponding to the sorted projection geometric features.