Earticle

In order to realize the high precision real-time measurement for the static objects, three coding-pitches triangular patterns phase-shifting profilometry based on modified Sunzi Theorem (ST) was proposed in this paper. First, according to Sunzi Theorem, the triangular pattern is designed. This Sunzi Theorem was adopted to unwrap three wrapped coordinate acquired from triangular patterns fringe images. The greatest common divisor of coding-pitches is obtained by the used projector. In unwrapping processing, the wrapped coordinate is considered as remainder of the absolute coordinate modulo of the coding-pitch. Generally there are two kinds of rounding policies for the remainder in real number set. If the rounding policy selection is wrong, the rounding result of remainder containing decimal fraction error which can lead the unwrapping result to quite away from the correct one. In order to solve the high sensitivity of the decimal fraction error, the decimal fraction difference is recognized as the criterion of the rounding policy selection for real number erroneous remainder. To verify the presented method in this paper, a 3D shape measurement experimental system is constructed using projector and camera. The experiment results shown that, a maximum standard deviation of measurement error to the rule 3D objects is 0.62mm, and the complex surface reconstruction with different surface reflectivity can be realized very well.

Triangular patterns phase shifting profilometry is a method of structured light whose three-dimensional reconstructions are susceptible to error from gamma distortion. In practice, the luminance nonlinearity caused by the gamma distortion effect of a digital projector and a digital camera yields undesired fringe intensity changes, which substantially reduce the measurement accuracy, and while the effects of the gamma distortion diminish with an increasing number of employed phase-shifted patterns. A gamma correction method based on the pre-coding of projected grating is proposed to reduce the measurement error caused by the gamma distortion. By applying an appropriate pre-coding value to the projected patterns, the gamma distortion effect is attenuated and the accuracy is enhanced. The linear least square is compensated the absolute coordinate residuals still existing after gamma correction. To verify the presented method in this paper, a 3D shape measurement experimental system is constructed using digital video projector and CCD camera. The experiment results shown that, the gamma pre-coding correction reduce the maximum residuals error of absolute coordinate by 72.2%. After the linear least square compensation, the maximum absolute coordinate residual is only 6.1% of without any correction or compensation. The reconstruction surface of a complex curve surface is hardly any waviness, which is clearly noted in the reconstruction of the same tested object without any correction or compensation.

무선 센서 네트워크에서 관심지역이 각 센서에 의하여 얼마나 잘 센싱되는지의 정도에 대한 커버리지(coverage)와 센서에 의하여 센싱된 데이터를 싱크노드까지 얼마나 잘 전달될 수 있는지의 정도에 관한 연결성(connectivity)은 중요한 연구 분야이다. 이와 관련하여 본 논문에서는 센서 네트워크에서 p-coverage와 q-connectivity ($q{\leq}6$)를 만족하는 최적의 센서 배치패턴 문제에 관한 연구 결과를 기술한다. 특히, 1-coverage의 경우 최적이라 알려진 삼각 격자 패턴에 대하여 p-coverage와 6-connectivity을 만족하도록 하는 배치 방법을 제시한다.

무선 센서 네트워크에서 관심지역이 각 센서에 의하여 얼마나 잘 센싱되는지의 정도에 대한 커버리지(coverage)와 센서에 의하여 센싱된 데이터를 싱크노드까지 얼마나 잘 전달될 수 있는지의 정도에 관한 연결성(connectivity)은 중요한 연구 분야이다. 이와 관련하여 본 논문에서는 센서 네트워크에서 p-coverage와 q-connectivity ($q{\leq}6$)를 만족하는 최적의 센서 배치패턴 문제에 관한 연구 결과를 기술한다. 특히, 1-coverage의 경우 최적이라 알려진 삼각 격자 패턴에 대하여 p-coverage와 6-connectivity을 만족하도록 하는 배치 방법을 제시한다.