CN110276792B - Model obtaining method and device based on digital filter - Google Patents
Model obtaining method and device based on digital filter Download PDFInfo
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- CN110276792B CN110276792B CN201910443724.6A CN201910443724A CN110276792B CN 110276792 B CN110276792 B CN 110276792B CN 201910443724 A CN201910443724 A CN 201910443724A CN 110276792 B CN110276792 B CN 110276792B
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T17/00—Three dimensional [3D] modelling, e.g. data description of 3D objects
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/50—Depth or shape recovery
- G06T7/521—Depth or shape recovery from laser ranging, e.g. using interferometry; from the projection of structured light
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2207/00—Indexing scheme for image analysis or image enhancement
- G06T2207/10—Image acquisition modality
- G06T2207/10004—Still image; Photographic image
- G06T2207/10012—Stereo images
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Abstract
The invention discloses a model obtaining method and a device based on a digital filter, wherein the model obtaining method is realized by a model obtaining device, the model obtaining device comprises a camera, the digital filter, a projector and a processor, and the model obtaining method comprises the following steps: calibrating the camera and the projector by the processor; the projector projects sine wave structured light; a camera shoots a sine wave structural light to generate a structural light image; the digital filter acquires a filtering image; the processor acquires the wrapping phase shift of the sine wave structured light according to the filtering image and acquires the absolute phase shift according to the wrapping phase shift; the projector projects the sine wave structured light on the target object; shooting an object image of a target object projected by sine wave structured light by a camera; and the processor acquires a three-dimensional model of the target object according to the absolute phase shift of the sine wave structured light and the object image. The method has the advantages of high operation speed, short time for obtaining the model of the object and high model precision.
Description
Technical Field
The invention relates to a model obtaining method and device based on a digital filter.
Background
Three-dimensional reconstruction refers to the establishment of a mathematical model suitable for computer representation and processing of a three-dimensional object, is the basis for processing, operating and analyzing the properties of the three-dimensional object in a computer environment, and is also a key technology for establishing virtual reality expressing an objective world in a computer.
The three-dimensional reconstruction of the grating projection is a three-dimensional reconstruction mode, the grating is respectively projected to a reference plane and the surface of a measured object, and the reference grating projected to the reference plane is not deformed because the reference plane is a horizontal plane; when the grating is projected on the surface of the measured object, the grating can generate deformation of different degrees because the projected grating is modulated by the height of the surface of the measured object. The heights of the placed measured objects are different, the phase change degrees of the gratings are different, and the phase change of the two-dimensional plane deformation stripes carries three-dimensional shape information of the surfaces of the objects. Therefore, by obtaining the phase change value, the height of the object at the corresponding point can be obtained, and the contour shape of the three-dimensional object can be obtained.
The existing grating projection has the defects of low modeling speed and low precision in three-dimensional reconstruction.
Disclosure of Invention
The invention aims to overcome the defects of low modeling speed and low precision in the three-dimensional reconstruction of the existing grating projection, and provides a model acquisition method and a model acquisition device based on a digital filter, which have the advantages of high operation speed, short time for acquiring a model of an object and higher model precision.
The invention solves the technical problems through the following technical scheme:
a model acquisition method based on a digital filter, wherein the model acquisition method is implemented by a model acquisition apparatus, the model acquisition apparatus includes a camera, a digital filter, a projector and a processor, and the model acquisition method includes:
the processor calibrates the camera and the projector;
the projector projects sine wave structured light;
a camera shoots a sine wave structure light to generate a structured light image;
the digital filter filters the low-frequency signal and the negative-frequency signal of the structured light image to obtain a filtered image;
the processor acquires the wrapping phase shift of the sine wave structured light according to the filtering image and acquires the absolute phase shift according to the wrapping phase shift;
the projector projects the sine wave structured light on the target object;
the camera shoots an object image of a target object projected by sine wave structured light;
and the processor acquires a three-dimensional model of the target object according to the absolute phase shift of the sine wave structured light and the object image.
Preferably, the processor is configured to determine the horizontal coordinate of the image point on the filtered image according to the formula f (x) = a 0 +a 0 cos(2πf 0 x) obtaining the wrapped phase shift of the image point.
Preferably, the processor is connected to the camera and the projector respectively, and the processor sends trigger signals to the camera and the projector respectively;
the camera comprises a camera lens, the projector comprises a projection lens, and the shooting direction of the camera lens and the projection direction of the projection lens are both aligned to the plane area;
the model acquisition method comprises the following steps:
the plane area is provided with a removable calibration pattern;
the camera shoots a plane area with only the calibration pattern as a calibration image;
the processor utilizes the calibration image to calibrate the camera and acquires camera calibration data;
the projector projects at least 2 calibration pictures with brightness to the plane area;
the camera shoots a calibration picture of each brightness on the plane area as a picture image;
and the processor utilizes the camera calibration data and the picture image to calibrate the projector and the camera.
Preferably, the projector projects at least 2 calibration pictures with brightness to the plane area, including:
the projector projects at least 2 gray scale calibration pictures to the plane area; or the like, or, alternatively,
the projector projects a calibration picture to the plane area, and projects gray level images with at least 2 gray levels on the calibration picture.
Preferably, the removable calibration pattern disposed on the planar area comprises:
displaying a calibration pattern on the plane area, wherein the color of the calibration pattern is variable;
the camera transmits a calibration image of a calibration pattern of at least 2 colors to the processor;
the processor calibrates the camera through all calibration images.
Preferably, the planar area includes a power supply module and a display panel, the display panel is provided with an electrochromic dye, and the power supply module is connected with the electrochromic dye.
Preferably, the plane area is a translucent white board, the calibration pattern is printed on the front surface of the translucent white board, a plurality of LED lamps are arranged on the back surface of the translucent white board, and the illumination direction of the LED lamps is aligned with the translucent white board;
the model acquisition method comprises the following steps:
the processor controls the brightness of the LED lamp;
the processor also sends a trigger signal to the camera after sending a brightness adjusting signal to the control chip.
Preferably, the planar area is a liquid crystal planar area, the liquid crystal planar area displays a preset pattern, the shape of the preset pattern is the same as that of the calibration pattern, and the color of the preset pattern is variable.
The invention also provides a model acquisition device based on the digital filter, which is characterized by comprising a camera, a projector and a processor, wherein the model acquisition device is used for realizing the model acquisition method.
Preferably, the processor includes a development board of DLP lightcraft 4500, model acquiring device includes a housing, the camera and the projector are both disposed in the housing, the camera includes a camera lens, and the projector includes a projection lens, and the camera lens and the projection lens are photographed on a front surface of the housing.
On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.
The positive progress effects of the invention are as follows:
the model acquisition device based on the digital filter has the advantages of high operation speed, short time for acquiring the model of the object and high model precision. .
Drawings
Fig. 1 is a flowchart of a model acquisition method according to embodiment 1 of the present invention.
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.
Example 1
The present embodiment provides a model obtaining apparatus based on a digital filter, which includes a camera, a projector, a digital filter and a processor.
The processor includes a development board model DLP lightcraft 4500, available from texas instruments, usa.
The processor is used for calibrating the camera and the projector;
the projector is used for projecting sine wave structured light;
the camera is used for shooting the sine wave structure light to generate a structured light image;
the digital filter is used for filtering the low-frequency signal and the negative-frequency signal of the structured light image to obtain a filtered image;
the processor is used for acquiring the wrapping phase shift of the sine wave structured light according to the filtering image and acquiring the absolute phase shift according to the wrapping phase shift; the absolute phase shift is obtained by wrapped phase shift of multi-frame sine wave structured light, and can also be obtained by means of space coding alignment projection.
The projector is used for projecting the sine wave structured light on a target object;
the camera is used for shooting an object image of a target object projected by sine wave structured light;
the processor is used for acquiring a three-dimensional model of the target object according to the wrapping phase shift of the sine wave structured light and the object image.
Specifically, the processor may be configured to determine a horizontal coordinate such as a pixel on the filtered image according to the formula f (x) = a 0 +a 0 cos(2πf 0 x) obtaining the wrapped phase shift of the image point.
The digital filter filters the low-frequency signal and the negative-frequency signal of the structured light image to obtain a filtered image, and the digital filter can obtain expressions of a real part and an imaginary part of an image point, wherein the imaginary part contains the information of the wrapping phase shift.
The model acquisition device of the present embodiment includes functions of a specific calibration camera and a projector.
The processor is respectively connected with the camera and the projector, and respectively sends trigger signals to the camera and the projector;
the camera comprises a camera lens, the projector comprises a projection lens, and the shooting direction of the camera lens and the projection direction of the projection lens are both aligned to the plane area;
the plane area is provided with a removable calibration pattern;
the camera is used for shooting a plane area only with the calibration pattern as a calibration image;
the processor is used for calibrating the camera by utilizing the calibration image and acquiring camera calibration data;
the projector is used for projecting at least 2 calibration pictures with brightness to the plane area;
the camera is used for shooting a calibration picture of each brightness on the plane area as a picture image;
the processor is used for calibrating the projector and the camera by using the camera calibration data and the picture image.
Specifically, the projector projects at least 2 calibration pictures with brightness to the plane area.
The calibration pictures of the two luminances can be obtained in one of two ways.
The projector projects at least 2 gray scale calibration pictures to the plane area; or the like, or, alternatively,
the projector projects a calibration picture to the plane area, and projects gray level images with at least 2 gray levels on the calibration picture.
The removable calibration pattern on the planar area comprises:
displaying a calibration pattern on the plane area, wherein the color of the calibration pattern is variable;
the camera is used for transmitting a calibration image of a calibration pattern of at least 2 colors to the processor;
the processor is used for calibrating the camera through all calibration images.
The function of calibrating the variable color of the pattern can be realized by the following 3 ways:
the display panel is provided with electrochromic dye, and the power supply module is connected with the electrochromic dye.
In a second mode, the plane area is a semitransparent white board, the calibration pattern is printed on the front surface of the semitransparent white board, a plurality of LED lamps are arranged on the back surface of the semitransparent white board, and the illumination directions of the LED lamps are aligned to the semitransparent white board;
the model acquisition method comprises the following steps:
the processor controls the brightness of the LED lamp;
the processor also sends a trigger signal to the camera after sending a brightness adjusting signal to the control chip.
In a third mode, the planar area is a liquid crystal planar area, the liquid crystal planar area displays a preset pattern, the shape of the preset pattern is the same as that of the calibration pattern, and the color of the preset pattern is changeable.
Fig. 1 shows that, with the above model obtaining apparatus, the present embodiment further provides a model obtaining method, including:
102, shooting a sine wave structure light by a camera to generate a structured light image;
104, the processor acquires the wrapping phase shift of the sine wave structured light according to the filtering image and acquires the absolute phase shift according to the wrapping phase shift;
105, projecting the sine wave structured light on a target object by the projector;
and step 107, the processor acquires a three-dimensional model of the target object according to the absolute phase shift of the sine wave structured light and the object image.
In step 103, for the horizontal coordinates such as the image point on the filtered image, the processor is configured to calculate the horizontal coordinate according to the formula f (x) = a 0 +a 0 cos(2πf 0 x) obtaining the wrapped phase shift of the image point.
The calibration method of the camera and the projector in the step 100 comprises the following steps:
a removable calibration pattern is arranged on the plane area;
the camera shoots a plane area with only the calibration pattern as a calibration image;
the processor utilizes the calibration image to calibrate the camera and acquires camera calibration data;
the projector projects at least 2 calibration pictures with brightness to the plane area;
the camera shoots a calibration picture of each brightness on the plane area as a picture image;
and the processor utilizes the camera calibration data and the picture image to calibrate the projector and the camera.
The projector projects at least 2 calibration pictures with brightness to the plane area, and the calibration pictures comprise:
the projector projects at least 2 gray scale calibration pictures to the plane area;
in addition, a calibration picture can be projected to the plane area through the projector, and a gray image with at least 2 gray levels can be projected on the calibration picture. Namely, the calibration pictures with two brightness are obtained by the way of lighting on the calibration pictures.
The removable calibration pattern on the planar area comprises:
displaying a calibration pattern on the plane area, wherein the color of the calibration pattern is variable;
the camera transmits a calibration image of a calibration pattern of at least 2 colors to the processor;
the processor calibrates the camera through all calibration images.
The color of the calibration pattern can be changed by the following 3 implementation methods:
the planar area comprises a power supply module and a display panel, wherein the display panel is provided with electrochromic dye, and the power supply module is connected with the electrochromic dye.
The plane area is a semitransparent white board, the calibration pattern is printed on the front surface of the semitransparent white board, a plurality of LED lamps are arranged on the back surface of the semitransparent white board, and the illumination directions of the LED lamps are aligned to the semitransparent white board;
the model acquisition method comprises the following steps:
the processor controls the brightness of the LED lamp;
the processor also sends a trigger signal to the camera after sending a brightness adjusting signal to the control chip.
The planar area is a liquid crystal planar area, the liquid crystal planar area displays a preset pattern, the shape of the preset pattern is the same as that of the calibration pattern, and the color of the preset pattern is changeable.
While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that these are by way of example only, and that the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and scope of the invention, and these changes and modifications are within the scope of the invention.
Claims (9)
1. A model acquisition method based on a digital filter, the model acquisition method being implemented by a model acquisition apparatus, the model acquisition apparatus comprising a camera, a digital filter, a projector, and a processor, the model acquisition method comprising:
the processor calibrates the camera and the projector;
the projector projects sine wave structured light;
a camera shoots a sine wave structure light to generate a structured light image;
the digital filter filters the low-frequency signal and the negative-frequency signal of the structured light image to obtain a filtered image;
the processor acquires the wrapping phase shift of the sine wave structured light according to the filtering image and acquires the absolute phase shift according to the wrapping phase shift;
the projector projects the sine wave structured light on the target object;
the camera shoots an object image of a target object projected by sine wave structured light;
the processor acquires a three-dimensional model of the target object according to the absolute phase shift of the sine wave structured light and the object image;
the processor is respectively connected with the camera and the projector, and respectively sends trigger signals to the camera and the projector;
the camera also comprises a camera lens, the projector comprises a projection lens, and the shooting direction of the camera lens and the projection direction of the projection lens are both aligned to the plane area;
the processor calibrating the camera and projector includes:
the plane area is provided with a removable calibration pattern;
the camera shoots a plane area with only the calibration pattern as a calibration image;
the processor utilizes the calibration image to calibrate the camera and acquires camera calibration data;
the projector projects at least 2 calibration pictures with brightness to the plane area;
the camera shoots a calibration picture of each brightness on the plane area as a picture image;
and the processor utilizes the camera calibration data and the picture image to calibrate the projector and the camera.
2. The model acquisition method as claimed in claim 1, characterized in that said processor is adapted to formulate the equation for the lateral coordinates of the image points on said filtered image
And acquiring the wrapped phase shift of the image point.
3. The model acquisition method as claimed in claim 1, wherein said projector projects at least 2 calibration pictures of brightness to said planar area, comprising:
the projector projects at least 2 gray scale calibration pictures to the plane area; or the like, or, alternatively,
the projector projects a calibration picture to the plane area, and projects gray level images with at least 2 gray levels on the calibration picture.
4. The method of model acquisition as claimed in claim 1, wherein providing a removable calibration pattern on said planar area comprises:
displaying a calibration pattern on the plane area, wherein the color of the calibration pattern is variable;
the camera transmits a calibration image of a calibration pattern of at least 2 colors to the processor;
the processor calibrates the camera through all calibration images.
5. The model obtaining method of claim 4, wherein the planar area comprises a power supply module and a display panel, the display panel is provided with electrochromic dye, and the power supply module is connected with the electrochromic dye.
6. The model acquisition method of claim 4, wherein the planar area is a translucent white board, the calibration pattern is printed on the front surface of the translucent white board, and a plurality of LED lamps are arranged on the back surface of the translucent white board, and the illumination directions of the LED lamps are aligned with the translucent white board;
the model acquisition method comprises the following steps:
the processor controls the brightness of the LED lamp;
and the processor also sends a trigger signal to the camera after sending a brightness adjusting signal to the control chip.
7. The model obtaining method of claim 4, wherein the planar area is a liquid crystal planar area, the liquid crystal planar area displays a preset pattern, the preset pattern has the same shape as the calibration pattern, and the color of the preset pattern is changeable.
8. A model acquisition apparatus based on digital filters, characterized in that the model acquisition apparatus comprises a camera, a projector and a processor, and the model acquisition apparatus is used for implementing the model acquisition method as claimed in any one of claims 1 to 7.
9. The model acquisition device as claimed in claim 8 wherein the processor comprises a DLP lightcraft 4500 development board available from texas instruments, usa, the model acquisition device comprising a housing, the camera and the projector both disposed within the housing, the camera comprising a camera lens, and the projector comprising a projection lens, the camera lens and the projection lens captured on a front face of the housing.
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| US9322643B2 (en) * | 2011-10-18 | 2016-04-26 | Nanyang Technological University | Apparatus and method for 3D surface measurement |
| US10928190B2 (en) * | 2017-09-27 | 2021-02-23 | Brown University | Techniques for shape measurement using high frequency patterns and related systems and methods |
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| US6049384A (en) * | 1996-02-27 | 2000-04-11 | Cyberoptics Corporation | Method and apparatus for three dimensional imaging using multi-phased structured light |
| CN104457615A (en) * | 2014-11-14 | 2015-03-25 | 深圳大学 | Three-dimensional digital imaging method based on generalized S transformation |
| CN106840036A (en) * | 2016-12-30 | 2017-06-13 | 江苏四点灵机器人有限公司 | A kind of diadactic structure light optimization method suitable for fast three-dimensional appearance measuring |
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