Digital 4D measuringMapvision systems are stand-alone measuring stations using solid state video cameras for image acquisition. Digital images provide reliable three-dimensional data on the size and shape of the target objects. Recent advances in videogrammetry have made real-time image capture and data analysis possible. Development of photogrammetric stations has now entered a new stage with the use of high-resolution digital video cameras in real-time three-dimensional measurement applications. These cameras provide both good image quality and a high degree of accuracy. Mapvision 4D Introduced in 1986, Mapvision represents one of the first real-time photogrammetric systems. These systems can be used for almost any optical non-contact measuring and object positioning task. Today, Mapvision is used in a variety of applications, including car body orientation and inspection, three-dimensional measuring of automotive glass, and robot guidance. The basic structure of the system is the same in all these applications. The main concept behind Mapvision is that by using a number of solid state cameras simultaneously the system can work with various types of targets. The system consists of CCD video cameras, a main control unit, a power source for the cameras, a scanner, and light sources. The three-dimensional co-ordinates of the object can be calculated by using two or more overlapping two-dimensional images. The measurement process does not require contact with the object, which means that it can be used with hostile objects and in difficult environments.
The new Mapvision 4D measurement system now offers a fourth dimension in measuring - the Quality Index. This is a unique solution developed to indicate how accurately each measured point lies on the object. The Quality Index – which has been patented - overcomes a number of problems associated with conventional methods, including the need for tedious manual cleaning of the 3D output data, and it provides ideal data for reverse engineering.
 Figure 1 On-line application for mobile phone component inspection. Digital Mapvision4D
Mapvision has previously used solid state analog video cameras for image acquisition. Now, a new version of the Mapvision 4D system uses solid state, high-resolution digital video cameras. These provide high quality images and high measuring accuracy. The increase in resolution means that more detailed images can be captured. The new Mapvision 4D unit using digital images has an accuracy of 2 mm (1s). The unit’s enhanced design features a chassis made of temperature and moisture stable carbon fibre for a light and compact but rigid structure. Sophisticated software, lightweight equipment and high-resolution digital video cameras ensure the accuracy of the Mapvision 4D measurement unit.
 Figure 2 The new Mapvision4D. The carbon fibre chassis makes for a lightweight and compact unit. GlassVision4D
GlassVision4D is a special version of the Mapvision4D system developed for working with glass. GlassVision4D differs from the basic measuring system for other materials in its use of a UV light source. This generates a UV spot which is reflected on to the glass surface by mirrors in the scanner. The UV light produces a visible fluorescent spot on the surface, which can be seen by the camera and measured three-dimensionally. The accuracy of the GlassVision4D system is increased by the integration feature of the solid state video cameras, as this prolongs the normal illumination time of the camera’s CCD sensor and thus increases the visibility of the spots projected on to the glass surface. Any number of spots can be projected on to the surface, which provides increased flexibility in the measuring process. Measuring is performed at a rate of 5 points per second.
 Figure 3 GlassVision4D is used in the automotive glass industry. The visible spots on the glass surface are generated by a UV laser. Advantages of real-time measurement
Real-time measurement provides many advantages. It is a non-contact process which is suitable for hostile objects. Many points can be measured simultaneously, and the results stored for post?processing and analysis. Statistical data can be collected for long-term tracking and analysis of the production process in on-line applications. Real-time measurement provides fast feedback and therefore helps to minimise production losses. Mapvision4D systems provide accurate measurement and feedback on the reliability of the measurement process. The resulting three-dimensional data can be used in off-line applications to make complete surface models and perform comparisons with existing CAD models.
Figure 4 One application of Mapvision systems is on-line positioning of car bodies for robotised operations. The sophisticated software can be easily customised for each application.
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