Research On 3D Photography System Using Grating Projection

Today noncontact 3D measurement and reconstruction technique is mainly applied to industry by way of"CCD camera and laser scan". Usually 3D measurement in industry can adopt laser with different power to scan the object within a longer time. From another point of view, it is enough for industry that the result of 3D measurement includes the 3D data and little vision effect. However, if 3D surface measurement system for human face takes the way of"CCD camera and laser scan", there is always possibility that the laser with a little more power does harm to people's eyes. Therefore 3D measurement for human face cannot adopt the laser. In addition, the result of human face 3D measurement should have not only 3D data with more precision, but also have art value. When 3D data cloud of human face, which reconstructed from 3D data measured, is engraved in the crystal glass, it is required that the shape and the expression are both alive. With the guidelines, the author researched on the 3D surface measurement and reconstruction technique for human face.Firstly, based on the light-section method, through repeating study and experiments, the thesis proposes a method of vision 3D measurement for human face using grating projection. Then taking human face measurement system developed in the thesis as the example, the author introduces the 3D measurement technique using grating projection.Secondly, considering the 3D measuring system described in the thesis, the author designed the control circuit for taking images. When the system takes images, the control circuit does sequential control to the outer photographing light and the light in the projector, according to the digital camera's controlling signals.Thirdly, as the basic part of the measuring process, the thesis introduced the system calibration of the 3D photography system using grating projection. It describes explicitly the calibration for the parameters of the grating projector (structured light plane) and does meaningful improvement based on the calibration of the digital camera and the grating projector. Also, it builds a precise model for the calibration of the 3D photography system and designs the complete experiment project for system calibrating.Lastly, the author develops the human face 3D measuring software of the 3D photography systems using grating projection. It uses the successfully calibrated system parameters to do the 3D reversing and gets the regular human facial 3D point group. The human face 3D measuring software uses its powerful 3D data processing ability to do optimization for the 3D points obtained by reversion, by doing this, it gets the 3D point group images which can be used directly by the outputting laser graving system. The laser graving system can express the human face's 3D images realistically within the crystal glass.