Human face measurement by projecting bandlimited random patterns

Abstract

This article presents a fast and accurate method to measure human faces for medical applications. To encode an object point, several random patterns are projected. A correlation technique, which takes only the area of one pixel into account, is used to locate the homologous points. It could be shown that band limited random patterns are helpful for noise reduction. The comparison of the point cloud of a measured plane with an ideal one showed a standard deviation less then 50 mum. Furthermore a depth difference of 20 mum is detectable.

Accurate depth sensing by filtering IR cost on the guide of RGB information

“…To find the correspondences robustly, researchers have developed many active methods to encode the scene. Among them, random speckle pattern [9][10][11][12][13] has attracted more and more attentiveness by researches these years. Schaffer et al [9] projected a sequence of speckle pattern onto the the object, and computed depth by temporal correlation on this pattern sequence.…”

“…Schaffer et al [9] projected a sequence of speckle pattern onto the the object, and computed depth by temporal correlation on this pattern sequence. Other researchers have tried to do depth sensing with spatial correlation technique on a pair input image [10][11][12][13]. However, because of the loss of structure information in the IR image, there are always unreliable values, especially on the object boundaries.…”

Absolute three-dimensional shape measurement using coded fringe patterns without phase unwrapping or projector calibration

“…Over the years, different methods have been developed. In general, they use random dots [11,47], bandlimited random patterns [49], binary-coded patterns [48,50], color structured patterns [51,52], or phase-shifted sinusoidal fringe patterns [53][54][55]. The overviews can be found in the literature [56][57][58].…”

Fast data acquisition for three-dimensional shape measurement using fixed-pattern projection and temporal coding

“…3,4 The former methods exploit the known pattern structure and rely on a combined projectorcamera calibration. The latter methods only induce a desired illumination structure onto the object and use multi-camera calibration as well as image correlation algorithms.…”

“…Due to the coherent illumination subjective speckles appeared and reduced the measurement accuracy compared to bandlimited patterns proposed by Ref. 3. As the statistical nature of the applied patterns implies that a simple movement of the pattern will preserve the statistical temporal coding of an object point, it is our idea to create a temporal setup using only one pattern, which is shifted in time.…”