Deformation speckle generation method based on reverse mapping method

A reverse mapping and speckle technology, which is applied in image generation, image data processing, filling planes with attributes, etc., can solve problems such as large system errors, complex generation methods, and difficult programming implementations

Inactive Publication Date: 2016-04-06
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the existing methods for preparing simulated speckle patterns have some shortcomings, such as large systematic er

Method used

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  • Deformation speckle generation method based on reverse mapping method
  • Deformation speckle generation method based on reverse mapping method
  • Deformation speckle generation method based on reverse mapping method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0097] Example 1: Rigid Body Translation

[0098]The reference image is a randomly generated speckle image with a resolution of 256×256pixels, a number of speckle particles of 2000, and a radius of 4 speckle particles. Using the original method and the reverse mapping method, a total of 20 translation images with an interval of 0.05 pixel are generated along the x direction, that is, the displacement of the image sequence is 0-1 pixel. Select the parameter variables in the DIC calculation to be consistent, analyze the two sets of speckle images, and calculate the error and standard deviation of the displacement field, expressed as follows:

[0099] e v = v ‾ - v t r u e

[0100] (10)

[0101] σ v = 1 ...

Embodiment 2

[0104] Example 2: Uniform deformation

[0105] The reference speckle pattern remains unchanged, and the original method and the reverse mapping method are used to generate a uniform stretching map along the y direction, the microstrain is from 1000-20000, and the Poisson's ratio takes the maximum value of 0.5. The parameter variables in the DIC calculation are selected to be the same, Analyze the two sets of speckle patterns, regard v in formula (10) as strain, and calculate the error and standard deviation of the strain field. The results are as follows Figure 7 , Figure 8 , Figure 9 and Figure 10 shown.

[0106] For the deformation in the x direction, when the microstrain is less than 10000, the calculation errors of the speckle patterns generated by the two methods are similar, and when the microstrain is greater than 10000, the error based on the original method increases almost linearly, while the calculation based on the reverse mapping method There is no obvious...

Embodiment 3

[0108] Example 3: Non-uniform deformation

[0109] The reference image is a randomly generated speckle image with a resolution of 500×500pixels, a number of speckle particles of 4000, and a radius of speckle particles of 4. Using the original method and the reverse mapping method, a non-uniform deformation map is generated along the y direction, respectively. The displacement field in the y direction conforms to the sin distribution, that is, v=Asin(2πy / T), A=1, T=200.

[0110] From Figure 11 It can be seen that the calculation error of the speckle pattern generated based on the original method is relatively large on the whole, and the maximum deviation can reach 2000 microstrain. And the latter error distribution law is more realistic, that is, the error is the largest at the strain peak. Compared Figure 12 It can be seen that the standard deviations calculated based on the two speckles are not much different, and the maximum is less than 300 microstrain. In general, th...

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Abstract

The invention discloses a deformation speckle generation method based on a reverse mapping method. The method is characterized in that speckle particles which are generated randomly are used to superpose and generate a reference image and each pixel point position gray level in a speckle picture is known; a shape function describes corresponding pixel point positions before and after deformation, and inverse transformation is performed on the shape function, which satisfies the following equation: (x, y)=F(x', y'), the position (x', y') after the deformation is known so that the position (x, y) before the deformation can be obtained. A gray level value of the position point before the deformation of a whole pixel position is generated through speckle particle gray level superposition. A gray level of the position before the deformation is extracted and fills into a corresponding position after the deformation so that a speckle picture after the deformation can be generated. A speckle picture generation process is simple and accords with a deformation requirement of an actual experiment.

Description

Technical field: [0001] The invention relates to a method for generating deformed speckles based on a reverse mapping method, which belongs to the related field of digital images. Background technique: [0002] Digital Image Correlation (DIC), characterized by natural texture or artificial speckle on the surface of the specimen, transforms the problem of material deformation into a matching search problem of feature points in images before and after material surface deformation. This method has the characteristics of high measurement accuracy, non-contact, full-field deformation measurement, and easy construction of the experimental bench, so it is widely used in experimental mechanics to analyze the deformation characteristics of materials. [0003] In order to improve the measurement accuracy of the digital image correlation method, it is necessary to analyze the factors that affect the algorithm, such as the size of the sub-region, the order of the shape function, the sub...

Claims

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Application Information

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IPC IPC(8): G06T7/00G06T11/40
CPCG06T7/0006G06T11/40G06T2210/44
Inventor 沈峘张佩泽沈翔
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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