Michal Emanuel Pawlowski

Shape and motion measurement of time-varying three-dimensional objects based on spatiotemporal fringe-pattern analysis

A method and tools recently applied in animation are presented, and the associated problems connected with combining the real and the virtual world are described. Approaches include creating computer graphics libraries of realistic 3-D objects and describing their animation in 3-D space. The presented method simplifies the process of virtual-object generation and provides the shape and movement of the monitored object. Optical structured-light methods supported by photo- grammetry are proposed for gathering the information about a shape, deformations of shape, and shifts of 3-D objects. The authors apply the spatiotemporal approach, in which the spatial analysis of fringe pattern delivers information about the shape of the object, while the temporal analysis of the intensity variation l(t) at a given pixel provides information about shape variations and out-of-plane displacement. The function I(t) is analyzed by the Fourier-transform method. Rigid-body motion of the object is determined by a photogrammetry-based marker tracking method. The methodology of measurement is presented, together with experimental results.

Studies of the properties of the temporal phase-shifting method applied to silicone microelement vibration investigations using the time-average method

Numerical simulations of the influence the phase step miscalibration and average intensity differentiation between the frames on the calculated interferogram contrast using the temporal phase shifting method (TPS) are presented. The fringe function includes in its argument the amplitude of vibration studied by the time-average method. Some features of the TPS method known from the interferogram phase calculations are confirmed and properties characteristic to contrast determination are established. Experimental studies of vibration resonant mode patterns of silicone microelements provide corroboration of theoretical and numerical findings.

Shape and Position Determination Based on Combination of Photogrammetry with Phase Analysis of Fringe Patterns

The basic methodologies used in animation are presented and their most significant problems connected with combining real and virtual worlds are recognised. It includes the creation of virtual object and description of its realistic movement. To perform these tasks an optical method based on fringe projection and marker tracking is applied. The spatial analysis of a projected fringe pattern delivers an information about shape of an object and its out-of-plane displacement. Additionally the analysis of positions of fiducial points at the object observed by two CCDs provides an on-line information about (x,y,z) co-ordinates of these points. Combining the information about object shape and 3D co-ordinates of fiducial points during the measurement enables to generate a virtual model of the object together with the description of its movement. The concept described above is experimentally tested and the exemplary results are presented. The further works to implement this technique are discussed.

Simplified time-averaged digital interferometry for vibration studies of microelements

Among interferometric techniques for analyzing mechanical properties and behaviors of microelements and microsystems time-averaged interferometry deserves particular attention because of its relative simplicity and data video display for arbitrary vibration frequency. This communication presents an implementation of the approach of Petitgrand et al. to quantitative analysis of vibration mode shapes based on the calibration of the fringe contrast variation as a function of the vibration amplitude. Fringe contrast maps for static and resonant frequency states are determined using the four-frame method with the phase shift of π/2 between the frames. Then the dynamic map is divided by the static one to obtain the square of the modulus of the characteristic fringe function. For sinusoidal vibrations it is the zero-order Bessel function J0 squared with the vibration amplitude encoded in its argument. The simplicity of our approach and speed of calculations are to be emphasized. The fringe processing method proposed is suitable for conventional two-beam and digital speckle interferometry. The results of experiments carried with silicone cantilever beams used in AFM resonant sensors are presented.

Application of shape-measuring optical methods in animation

The methodologies and tools used recently in animation are presented and their most significant problems are recognized. It includes creating of libraries of realistic 3D objects and describing the models of animation in 3D space. As a solution optical methods using structured light are proposed for gathering information about shape of 3D objects. The fringe projection system is applied for determination of absolute co- ordinate of 3D objects in respect to their global shape and local texture. Additionally the measurements at sequential stages of the object movements are performed. This information is the base to calculate the trajectories of points movement, and latter to predict the model of animation. The concept described above is experimentally tested on simple 3D objects. The further works required to apply the methodology presented for description of complex, realistic objects are discussed.

Monitoring and measurement of movement of objects by fringe projection method

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.

Spatio-temporal approach to shape and motion measurements of 3D objects

ABSTRACT The methodologies and tools used recently in animation are presented and their most significant problems connected withcombining real and virtual world are recognised. It includes creating of computer graphics libraries of realistic 3D objectsand describing the models of animation in 3D space. The presented measurement methodology simplifies the process ofgeneration ofvirtual objects and gives as the result: shape and movement description ofthe monitored object.Optical structured light methods are proposed for gathering the information about a shape, deformations of 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 1(t) in the given pixelprovides information about shape variations and out-of plane displacement. 1(t) is analysed by Fourier transform basedmethod. Determination of rigid body motion of the objects is performed by photogrametry based marker tracking method.The methodology of measurement is presented together with exemplary experimental results.

Environment model for unmanned flying vehicles based on simulated radar data

The main goal of AURA (Autonomous collision avoidance system for unmanned flying vehicles based on active teledetection method) project is to create an collision avoidance system (comparable to see-and-avoid requirements for manned aircraft) that can be used in unmanned aerial vehicles. For testing purposes there was necessity to develop simulation environment, which could be used to generate the data required for testing of collision avoidance algorithms. The program allows adjusting of the operating parameters of the simulated device to ensure optimal efficiency. It gives us the possibility of preparing such test cases which would be very difficult or even impossible to prepare when using real aircraft. This paper includes description of developed simulator and its graphical user interface.

New method for testing the objectives for miniature CCD cameras

In the paper we present a new method for testing objectives for CCD camera. The method is based on determination of the modulation transfer function. The results were verified by experiments performed at the specially designed automated testing. The method, accompanying program software and hardware are applied in the teaching process of photonics at Institute of Micromechanics and Photonics, Warsaw University of Technology.

Monitoring of shape and position of objects varying in time based on spatio-temporal analysis of fringe patterns and measurement of 3D coordinates of fiducial points for multimedia applications

The basic methodologies used in animation are presented and their most significant problems connected with combining real and virtual worlds are recognised. Measured objects are classified into groups based on their mechanical properties and behaviour. The optical methods of shape and movement parameters determination adequate for fast virtual object generation are presented. Combination of various fringe projection techniques with photogrammetry is proposed to calculate the temporal shape and position of the object points. The spatio-temporal analysis of a projected fringe pattern delivers information about object shape and its out-of-plane deformation. The shape of measured object is calculated based on algorithm spatial carrier phase shifting technique. The analysis of marker dislocations during the measurement provides information about object shifts within the measurement volume. Combined information about object shape and its dislocation during the measurement enable to generate a virtual model that can be used to generate e.g.: realistic animation. The short comparison between proposed method and currently available systems is given and exemplary results of measurements are presented. The further directions of development of proposed techniques are presented.