3d Spatial Scales Ranging Study Of Digital Cameras

With the development of national economy, our country has made great achievements in bridge construction. Bridge is an important part of road. Each year, many newly-built bridges and roads are been checked and accepted by quality and security system. So how to find a new and efficient way to check and evaluate the security of the bridge and reliability of the structure in a scientific way has became a significant topic today.This subject is based upon pefecting the application of digital speckle correlation method (DSCM) with double microscopes in strain measurement mechanism. The technology employs tele-photo in measuring flexibility and vibration of the bridge. The paper tries to solve the problem of tele-photo measurement coverd in the subject, which uses digital camera to study the distance between the object and camera.The paper first introduces the foundamental knowledge and optics of camera, and of the perspective imaging theory covered in research of distance measurement with digital camera (three different types of coordinate frames, photography image model, 3D cues in 2D images). The paper makes detailed research about the properties of imaging resolution, depth of a field, circle of confusion (COC) of digital camera and brought forward the corresponding theoretic grounds and algorithm of 3D-range of digital camera. We use computer to process the digital images taken on the spot by the digital camera in the same direction. After drawing a line on the object in the picture, input the related data of the object, then you may get the real distance between the object and the lens plane.The research reveals that if you get the geometrical size of the object, the measurement of the spatial distance is only related to the focus, resolution of the image sensor and the size of the object in the image, which can be described in very simple mathematical means. The result of the experiment suggests the relative error between the results of the spatial distance measurement of the objects and the real distance is almost less than 5%. This method is easy to operate, accurate and can be used in pratical measurement in positions of various distances. The technology can be applied in measuring spatial distance of flexibility of the armoured concrete bridges in the distance, and it has laid a foundation for the subject of measurement of flexibility.