Submillimeter 3D surface reconstruction of concrete floors

Sammanfattning: During the creation of any concrete floor the concrete needs to be grinded down from it's very rough newly poured form to a more usable floor surface. Concrete floor grinding is very special in that the work area is often immensely large while the height difference on the surface is incredibly small, in-fact the the largest local difference of the surface from a peek to a valley during the grinding process is submillimeter and goes down to micrometer scale. Today's methods for measuring concrete surfaces are very few and all output one dimensional profiles of the surface in very time consuming processes which makes them unsuitable for real-time analysis of the surfaces during the grinding process. Because of this, the effectiveness of the work is dependent on the experience and intuition of the operator of the grinding machine as they have to make the decision of when to move on to the next step in the grinding process. Therefore it is desirable to create a better method for concrete surface measurement that can measure big areas in a short period of time. In this project a structured light method using sinusoidal phase shifting is implemented and evaluated with an easily movable setup that can measure the height of a concrete surface over an area. The method works by encoding the surface with a phase using a projector and analysing how the phase encoding warps when imaging it from an angle. By triangulation this can be made into a height map of the measured area. The end results show that the method is promising for this application and can detect the submillimeter differences. However, more suitable hardware and a more reliable calibration procedure are required to move this prototype towards a more practical measuring device.