KEYWORDS: Virtual reality, Optical testing, 3D metrology, Digital Light Processing, 3D visualizations, Multimedia, Photonics, Data processing, Clouds, Visualization
The biggest challenges in multimedia technologies are connecting with createing fully interactive virtual reality (VR) systems. This requires generating numerically or even better gathering real data about static or dynamic 3D objects and scenes and delivering them to virtual reality environment.
Application of the structure light measurement system based on digital light projection supported by special data coding and processing technology allow to record 3D data with significantly higher accuracy of reconstructed shape and simplified data manipulation process.
In the paper the general concept of virtual reality system supported by data gathered by means of structure light projection is presented. The methodology of conversion of cloud of measurement points (x,y,z,R,G,B) into virtual reality environment is described. The methodology of real time visualization of variable in time 3D object based on its coding by means of specially formed contours and their B-spline approximation is presented. The applicability of the methodology has been shown at the case of real object monitoring. The total processing path was successfully tested.
Fulfilling the recent needs of visualization of variable in time 3D objects in virtual reality environment requires development of new approach towards combining rapid 3D shape measurement with data filtering, coding and streaming. These operations have to enable performing real-time transmission and visualization of 3D data in virtual reality. In the paper the novel system based on digital structure light projection applied to gather 3D data representing variable in time objects and extended numerical procedures coupled with virtual camera concept for interactive object visualization is presented. The proposed measurement and data processing methodology has been verified successfully at computer generated models of moving and morphing 3D objects. Both types of data have been visualized with the average frequency of 10 frames per second in virtual reality environment.
The recent needs of visualization of variable in time 3D objects require development of new approach towards rapid 3D shape measurements. One of them applies colour structure light projection which utilizes combined multicolour phase-shifted and colour Gray codes. The usage of colour multiplexing enables to reduce the number of images required for shape measurement to one (slow gradients of shape) or three (high gradients) images and provides quasi real-time analysis. However the usage of projection and detection of colour patterns may produce significant errors due to noncorrect analysis and interpretation of images. These phenomena are shown at exemplary results of analyzing of real colour coded fringe patterns projected onto monocolour 3D objects. The main sources of errors connected with the use of a digital colour light projector and colour CCD camera (with single and 3 CCD matrixes) are discussed. The analysis of RGB and HSI color models are shown in reference to the system calibration procedure. Additionally the basic concept of system calibration and modification of images processing for the case of color 3D object analysis is put forward.
KEYWORDS: 3D metrology, Calibration, Virtual reality, Cameras, Visualization, Clouds, 3D modeling, 3D acquisition, Imaging systems, 3D image processing
The general concept of 3D data acquisition and processing system, which enables gathering information about shape, morphing and movement of 3D object for virtual environment, is presented. The methodology based on combined structured light, spatio-temporal phase analysis and photogrametry is described. For VR the concept of a virtual camera, as the mean for interactive object visualization is introduced. The exemplary, initial results of implementation of such system are presented.
The methodologies and tools used recently in animation are presented and their most significant problems connected with combining real and virtual world are recognized. It includes creating of computer graphics libraries of realistic 3D objects and describing the models of animation in 3D space. The presented measurement methodology simplifies the process of generation of virtual objects and gives as the result: shape and movement description of the monitored object. Optical structured light methods are proposed for gathering the information about a shape, deformations of the shape and shifts of 3D objects. Authors apply the spatio-temporal approach, in which the spatial analysis of fringe pattern delivers information about initial shape of the object, while the temporal analysis of intensity variation I(t) in the given pixel provides information about out-of-plane displacement. I(t) is analyzed alternatively by adaptive sinusoidal fitting algorithm or by Fourier transform based methods. The comparison between these methods is given and exemplary measurements are presented.
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