1. A non-contact method of inspecting the topography of an area of an object via analysis of the phase of a pattern projected on the object, comprising: i) taking a first image of the object, obtained from a first perspective, on which an optical pattern is projected; ii) taking a second image of the object, obtained from a second perspective, on which an optical pattern is projected but in which the optical pattern, as it falls on the object, in the second image differs to that in the first image; and iii) determining data describing the topography of at least a region of the object based on phase data relating to the phase of at least a region of the optical pattern as imaged in the first image in which phase data obtained from a corresponding region of the object as imaged in the second image is used to resolve any ambiguity in the phase or topography data obtained from the first image.