The present general inventive concept is directed to moving spatial sensors and associated image and signal processing for inspection of materials and/or structure in a region of interest. The general inventive concept finds applicability in, among other things, imaging of hidden structures and objects in and behind obscuring surfaces, such as, for example, walls. The present general inventive concept achieves benefits over other devices, such as so-called “stud-finders” and other related construction and building inspection tools, by providing a spatial image of the area hidden by an obscuring barrier, such as wall covering material.
Conventional stud finders provide users with information relating to hidden structure in walls, such as the positions of wooden and metal studs, and in some cases, electrical wires or pipes. This is achieved by an assortment of data acquisition techniques, including measurements of material density or material transitions via, among others, RF, ultrasonic, magnetic, electrical and dielectric capacitance measurements. Stud finders are typically divided into those that detect the center of the stud, or other object of density, and those that detect edges at a sharp density transitions. One limitation in the prevailing art is that only a single stud, or other object of interest, can be visually located at one time, using the hand-held devices' built-in indicators. Typical designs allow only a small region to be examined at a time; it is up to the user to mark the wall in such a way as to make sense of the overall structure behind it. If exploring the wall to seek out specific structures, as opposed to just the nearest stud, extensive marks with tape, pen, pencil or the like must be made before the hidden structure can be visualized. An additional limitation is that the sensors are generally preferentially biased to detect transitions in only one dimension. While this is adequate for the primary task of stud finding, it requires the user to rotate the device and start over to look for other structure, such as horizontal blocking between studs. In the case of ceilings, floors, or other arrangements in which structural members are concealed, a user may be required to possess and apply learned experience in determining the expected orientation of studs, beams, joists, etc. A further limitation of present devices is in dynamic range; conventional devices are generally self-calibrating and require learned finesse on the part of the user and often multiple attempts in order to successfully identify internal wall structure. Moreover, devices of present art generally reduce sensitivity to accommodate the strongest sensor return, thus making it very difficult to detect multiple hidden objects of differing densities and/or depths without many small iterative passes across the wall surface.