To some extent, 3D inspection implementation is complex because of a uniform scanning: typically, 3D inspection sensors cannot apply different scanning parameters to different regions inside the field-of-view. For example, most existing scanning profilometers and some structure light implementations scan in only a single direction. Single-direction scanning results in non-optimal angles of illumination – particularly when an edge feature is parallel to the illumination – and has the potential for 3D ‚drop out‘ when the angle of the illumination source is obscured from the camera(s). Another constraint is that virtually all existing 3D solutions produce an image with a fixed scan density. This can result in over-sampling of parts of the image to achieve resolution necessary for local features, or under-sampling of features that require higher density.
