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Cyclic code 3D measurement method with the combination of trapezoid grayscale and binary grayscale

A measurement method and combined technology, applied in measurement devices, instruments, optical devices, etc., can solve problems such as large amount of calculation, limited measurement speed, large error, etc., to increase the measurement range, improve accuracy and precision. high degree of effect

Inactive Publication Date: 2010-06-09
HARBIN UNIV OF SCI & TECH
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Problems solved by technology

However, although the combination of Gray code and ordinary phase shift solves the problem of continuous projection angle, it does not substantially improve the accuracy of spatial point measurement and sampling density, and it is necessary to project a full-bright and full-dark pattern for normalization. This method will have a huge calculation of arctangent, and the amount of calculation is very large, which limits the speed of measurement
And the combination of these two methods has a large error of the gray code cycle, and the accuracy cannot be guaranteed

Method used

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  • Cyclic code 3D measurement method with the combination of trapezoid grayscale and binary grayscale
  • Cyclic code 3D measurement method with the combination of trapezoid grayscale and binary grayscale
  • Cyclic code 3D measurement method with the combination of trapezoid grayscale and binary grayscale

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Embodiment 1

[0027] combined with figure 1 and specific embodiments to further describe the present invention.

[0028] A cyclic code 3D measurement method combining trapezoidal grayscale and binary grayscale, comprising the following steps:

[0029] (1) Firstly, the binary gray-scale Gray code coded light is projected to the measured object, as shown in the attached figure 2 , to obtain the Gray code period with the fewest encoding steps;

[0030] (2) Then project three pieces of trapezoidal phase-shift gray-scale intensity code light in turn, and give a higher-precision measurement space division on the basis of its Gray code;

[0031] (3) The combination of the two obtains continuous single-valued measurement space division, thereby obtaining three-dimensional coordinate values.

[0032] In step (1), first we project n different binary gray-scale Gray code patterns onto the object, then collect n gray-scale images into the computer, and binarize the n images, according to the binari...

Embodiment 2

[0050]The traditional Gray code structured light measurement method needs to project two fully bright and fully dark images on the basis of projecting the Gray code pattern, and then perform normalization, otherwise the measurement cannot be performed. Compared with the Gray code, the present invention has a maximum value and a minimum value for each pixel in the three trapezoidal phase-shifted Gray codes, and has the feature of self-normalization, without the need for all-bright and all-dark images. While ensuring the measurement accuracy, the number of projections is reduced to simplify the measurement.

Embodiment 3

[0052] A trapezoidal phase-shift gray intensity code method is proposed corresponding to the jump point of the gray code from the center of the trapezoidal slope.

[0053] When the previous Gray code combined with phase shift method (such as a phase combined with Gray (Gray) code proposed by the National Mold CAD Engineering Research Center of Shanghai Jiaotong University) is used to divide the projection angle space of the structured light measurement system, the Gray code period and the phase shift period The edges are completely corresponding. When the absolute phase is actually calculated, the initial period distribution obtained after decoding is not the same as the theoretical value, but there is a fringe period error at the period boundary of the projected pattern, which we call period misalignment.

[0054] In response to this problem, the present invention proposes the trapezoidal phase shift intensity ratio method corresponding to the gray code jump point method of th...

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Abstract

The invention relates to a cyclic code 3D measurement method with the combination of a trapezoid grayscale and a binary grayscale. An optical 3D measurement technology belongs to non-contact measurement and has the main advantages of no contact with the surface of a measured object and high sampling density. In the optical 3D measurement technology, a structured light coding method has wide application prospect in the fields of 3D reconstruction, industrial measurement, and the like by the advantages of high accuracy, high measurement speed, low cost, and the like. The method comprises the following steps of: (1) firstly, obtaining a gray code period by projecting a binary grayscale gray code to an object to be measured in least coding steps; (2) then sequentially projecting three trapezoid phase shift grayscale strength codes and providing measurement space division with higher precision on the basis of the gray code; and (3) obtaining the measurement space division of a continuous single-value by the combination of the gray code period and the measurement space division so as to obtain a 3D coordinate value. The invention is applied to the 3D measurement technology.

Description

Technical field: [0001] The invention relates to a cyclic code 3D measurement method combining trapezoidal gray scale and binary gray scale. Background technique: [0002] The existing time coding methods all divide the projection angles based on binary codes and Gray codes, or further subdivide the projection angles by combining four-step phase shift method or vertical layering method on this basis. [0003] When gray codes are used to divide the projection angle, only a limited division of the measurement space can be carried out, and each of the thinnest stripes in the division corresponds to a discrete value, and only limited spatial encoding values ​​can be obtained for the measurement space points. Therefore, adjacent measured points will have the same code value in one direction, that is, all the measured points in the thinnest stripe have the same Gray code value. For high-precision three-dimensional measurement, Gray code measurement accuracy is not high enough. W...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/25
Inventor 于晓洋单鹂娜
Owner HARBIN UNIV OF SCI & TECH
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