Improved Three-step Phase Shifting Profilometry Using Digital Fringe Pattern Projection

In this paper, an improved method for three-step phase shifting profilometry (PSP) is presented to eliminate the errors introduced by the second order harmonic when digital projection are used to generate fringe patterns. Firstly, the error caused by the second order harmonic is theoretically analyzed. Then based on the error analysis and principle of PSP, we propose a novel approach, called improved threestep phase shifting profilometry (I3PSP), to eliminate the influence of the second order harmonic. Finally, simulations are performed to verify the effectiveness of the proposed I3PSP, which demonstrate that the reconstruction accuracy of using three-step PSP has been significantly improved by the proposed I3PSP

Classificação de laranjas através da técnica de moiré por phase-shifing / Classification of oranges by way through the moiré technique per phase-shifting

A seleção de frutos por forma, emprega equipamentos mecânicos que, por muitas as vezes, danifica o produto, sendo necessário buscar alternativas de classificação que evitem injúrias nos seus tecidos, dos quais ocasionam a diminuição no seu tempo de prateleira. Diante disso, torna-se necessário buscar alternativas que classifiquem o fruto pela forma sem danificá-lo, e que possibilite a seleção para o mercado consumidor. Neste sentido, objetivou-se com este estudo, desenvolver uma técnica de classificação de laranjas por forma, através do uso de métodos ópticos e sem contato. Utilizou-se a técnica óptica de Moiré por Phase-Shifting, em laranjas da cultivar tipo Pêra. Os equipamentos utilizados foram: câmera fotográfica digital, projetor multimídia, tinta spray branco fosco, plano de fundo liso e branco, além dos softwares ImageJ, Rising-Sun Moiré e Finge Projection. No primeiro momento, foram extraídas cinco imagens de cada corpo de prova, quatro com aplicação de grades sinusoidais defasadas em 90 graus, e uma com o plano de fundo. As imagens foram convertidas em RGB para escala de cinza (8 bits) para obtenção de mascaras vetoriais e aplicação de filtros na eliminação de ruídos, em seguida foi realizada a junção de cada imagem com o plano de fundo, com as grades defasadas em 90 graus, gerando quatro novas imagens. O terceiro passo, compreendeu a junção das imagens, gerando uma única imagem do modelo digital topográfico, em seguida o modelo foi processado no software ImageJ, para a obtenção da escala de pixels, para corelacionar uma relação direta, pixel/cm. Os resultados mostraram-se ser bastante satisfatórios na implementação dessa técnica para classificação de laranjas por forma, do qual permitil obter a curvatura do fruto e sua classificação. No entanto, necessita-se de mais repetições, para que se determine um fator de correção adequado, no processamento das imagens, de forma a se obter dados dimensionais mais exatos.

Real-time 3-D Reconstruction by Means of Structured Light Illumination

Structured light illumination (SLI) is the process of projecting a series of light striped patterns such that, when viewed at an angle, a digital camera can reconstruct a 3-D model of a target object\u27s surface. But by relying on a series of time multiplexed patterns, SLI is not typically associated with video applications. For this purpose of acquiring 3-D video, a common SLI technique is to drive the projector/camera pair at very high frame rates such that any object\u27s motion is small over the pattern set. But at these high frame rates, the speed at which the incoming video can be processed becomes an issue. So much so that many video-based SLI systems record camera frames to memory and then apply off-line processing. In order to overcome this processing bottleneck and produce 3-D point clouds in real-time, we present a lookup-table (LUT) based solution that in our experiments, using a 640 by 480 video stream, can generate intermediate phase data at 1063.8 frames per second and full 3-D coordinate point clouds at 228.3 frames per second. These achievements are 25 and 10 times faster than previously reported studies. At the same time, a novel dual-frequency pattern is developed which combines a high-frequency sinusoid component with a unit-frequency sinusoid component, where the high-frequency component is used to generate robust phase information and the unit-frequency component is used to reduce phase unwrapping ambiguities. Finally, we developed a gamma model for SLI, which can correct the non-linear distortion caused by the optical devices. For three-step phase measuring profilometry (PMP), analysis of the root mean squared error of the corrected phase showed a 60х reduction in phase error when the gamma calibration is performed versus 33х reduction without calibration

Development Of A New Method For Volume Measurement Based On Moiré Techniques [desenvolvimento De Um Novo Método Para Medida De Volume Baseado Em Técnicas De Moiré]

This research work reports a shadow moiré method applied in generating spatial dimensions of solid figures. The focus of this work is to study as well as to turn feasible a new method of measuring object shape as plant organs. Selected experimental setup included four Ronchi optical grids out of phase by 1/4 of period, a conventional white light source and a digital camera. The samples were hold by a support, following by data acquisition process generating four elevation digital models (EDM). EDM were employed to create the tridimensional Model (TM) which, in turn, was also applied to generate the object volume. The method of water volume displacement has been used for data comparison in which the change of liquid volume is equal to the object volume. The results allowed to state that moiré techniques can be used for volumetric determination of irregular objects as fruits and others vegetable organs. The work includes error determination.4438792Abràmoff, M.D., Magalhães, P.J., Ram Sunanda, J., Image processing with Image J (2004), 11 (7). , Berkshire Common, Laurin Publishing, Biophotonics InternationalAlbiero, D., Maciel, A.J.S., Dal Fabbro, I.M., Rodrigues, S., Mazzeti Filho, V., Moiré assisted deformation distribution study on soil-tire system (2005) Proceedings of the International Congress on Information Technology in Agriculture, Food and Environment, ITAFE05., pp. 681-683. , (CD ROM) vol.II, Balcali Campus, çukurova University, Adana, Turkey, October 12-14, 2005Amidror, I., (2000) The theory of the moiré phenomenon, p. 474. , Kluwer Academics Publishers. DordrechtHu, Y., Xi, J., Chicharo, J., Yang, Z., Improved Three-step Phase Shifting Profilometry Using Digital Fringe Pattern Projection (2006) Proceedings of the International Conference on Computer Graphics, Imaging and Visualisation (CGIV'06)., , IEEE Computer Society. Sydney, Australia;Dal Fabbro, I.M., Albiero, D., Gazzola, J., Rodrigues, S., Rabelo, G.F., Fujii, A.K., Moiré assisted mechanical behavior of sugarcane stalks under axial compression (2005) Proceedings of the International Congress on Information Technology in Agriculture, Food and Environment, ITAFE05., 1, pp. 242-245. , (CD ROM) Balcali Campus, çukurova University, Adana, Turkey, October 12-14, 2005Degrieck, Joris., Van Paepegem, W., Boone, P., Application of Digital Phase-shift shadow moiré to micro deformation measurements of curved surfaces (2001) Optics and Lasers in Engineering, 36, pp. 29-40Demarzo, M.A., Affonso, E.A., Dal Fabbro, I.M., Application of a moiré interferometric technique in studying wooden structural elastic connections (2003) Proceedings of the International Congress - Information Technology in Agriculture, Food and Environment, ITAFE 2003, 1, pp. 689-692. , Ege University, Bornova, Izmir, Turkey, October, 07 -10 2003Lino, A.C.L., (2002) Moiré Optical Technique Applied to the Study of Irregular Surfaces, Maters Thesis., p. 86. , Faculty of Agricultural Engineering, State University of Campinas, SP, Brazil;Marotti, D., Dal Fabbro, I.M.D., Lino, A.C.L., (2008) Computational Implementation of Moiré Methods Applied to Three Dimensional Image Reproductions, , Umpublished Paper. State University of Campinas, SP, Brazil;Mazzeti Filho, V., (2004) Use of moiré interferometry to study the dynamic stresses on floppy disks, p. 136. , Dissertation (MSc in Agricultural Engineering), State University of Campinas, Campinas, SP, Brazil;Minamisawa, R.A., Gazolla, J., Albiero, D., Dal Fabbro, I.M., Beraldo, A.L., Shadow moiré technique applied in testing composite material (2005) Proceedings of the International Congress on Information Technology in Agriculture, Food and Environment, ITAFE05., pp. 237-241. , (CD ROM) vol.I. Balcali Campus, çukurova University, Adana, Turkey, October 12-14, 2005Oster, G., Nishijima, Y., Moiré patterns (1964) Scientific American Resource Library: Readings in the Physics Sciences and Technology. Washington, 3, pp. 54-63. , Offprints 291-326Oliveira, S.A.G., (1988) Development of materials for reflection photoelasticity, p. 93. , Dissertation in Mechanical Engineering - Faculty of Mechanical Engineering, Federal University of Uberlândia, MG, Brazil;Post, D., Han, B., Ifju, P., (1994) High sensivity moiré: Experimental analysis for mechanics and materials, , New York: Spring-Verlag;Quan, C., He, X.Y., Wang, C.F., Tay, C.J., Shang, H.M., Shape measurement of small objects using LCD fringe projection with phase shifiting (2001) Optics Communication, 189, pp. 21-29Sciammarella, C.A., The moiré method - A review (1982) Experimental Mechanics, 44 (8), pp. 418-433Vieira, M.A.P., Dal Fabbro, I.M., Laurenti, R., Application of a moiré interferometric technique in a simple structural member vibration analysis (2003) Proceedings of the International Congress - Information Technology in Agriculture, Food and Environment, ITAFE 2003, 1, pp. 599-603. , Ege University, Bornova, Izmir, Turkey, October, 07 -10, 200