CN112712585B - Three-dimensional imaging system and method based on arc binary coding phase shift fringe projection - Google Patents
Three-dimensional imaging system and method based on arc binary coding phase shift fringe projection Download PDFInfo
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- G—PHYSICS
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- 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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- G06T2207/00—Indexing scheme for image analysis or image enhancement
- G06T2207/30—Subject of image; Context of image processing
- G06T2207/30196—Human being; Person
- G06T2207/30201—Face
Abstract
The invention relates to the field of optical three-dimensional measurement, in particular to a three-dimensional imaging system and method based on arc binary code phase shift fringe projection. The system comprises: the device comprises an illumination unit, an optical mask, an optical projection lens, an imaging unit, a control unit and a three-dimensional reconstruction algorithm module, wherein the optical mask is provided with an arc phase-shift stripe pattern and rotates at a constant speed, emergent light emitted by the illumination unit is modulated through rotation of the optical mask, a phase-shift stripe structure light pattern is obtained, and the phase-shift stripe structure light pattern is projected onto a target to be detected through the optical projection lens. And the three-dimensional reconstruction algorithm module is used for realizing the three-dimensional reconstruction of the target to be detected according to the projection image sequence containing the geometric information of the target to be detected. Compared with the traditional digital projection, the system can provide higher contrast, higher resolution and faster projection speed, and has low complexity and small installation space requirement, thereby realizing the system design with compact structure and low cost.
Description
Technical Field
The invention relates to the field of optical three-dimensional measurement, in particular to a three-dimensional imaging system and method based on arc binary code phase shift fringe projection.
Background
The three-dimensional face recognition technology combines the facial texture characteristics and three-dimensional structure information, so that the limitation of factors such as environment, gesture, expression and the like on the face recognition rate can be greatly reduced. The premise of the rapid development and application of the three-dimensional face recognition technology is that three-dimensional face data are acquired, and the most widely adopted optical three-dimensional measurement technology based on the triangulation principle is used at present to acquire the three-dimensional face data. The three-dimensional surface shape data is obtained by projecting the structured light field to the surface of the target to be detected, a monocular or binocular camera is adopted to collect the deformed image modulated by the surface of the target to be detected, and information such as gray level, phase and the like is analyzed to recover the three-dimensional information. The optical mask coding can be used for enriching or increasing the surface texture of the detected face object, so that the accuracy and reliability of the three-dimensional reconstruction result are improved. In addition, the number of the structured light patterns projected to the surface of the object to be measured can be increased to improve the three-dimensional measurement accuracy.
At present, three-dimensional modeling products on the market mostly adopt sinusoidal stripe or speckle projection technology, and compared with a three-dimensional measurement system based on speckle patterns, a three-dimensional measurement system based on sinusoidal stripe phase shift projection can obtain more excellent three-dimensional reconstruction effect. However, the three-dimensional reconstruction system of sinusoidal fringe projection requires precise phase shift, and commercial digital projection devices such as DLP (Digital Light Processing) and LCOS (Liquid Crystal on Silicon) are generally adopted, so that the system has the defects of large volume, high cost and the like, and is limited in three-dimensional face recognition application requiring balance of cost, precision and integration level. Compared with a commercial digital projector, the projection device based on the structured photo-optical mask has the advantages of compact structure, low power consumption and high integration level, and a plurality of commercial products which adopt low-cost speckle template projection, including Orbbec, realSense and Kinect V1.0, are presented at present, but three-dimensional data imaging of novel and compact-structure phase-shift fringe pattern projection is not reported through the low-cost structured photo-optical mask.
Disclosure of Invention
The invention constructs a novel phase shift fringe light field pattern projection device with compact structure, fixes an optical mask with an arc phase shift fringe pattern on a central axis perpendicular to a motor, drives the optical mask plate to rotate through the motor, and simultaneously adopts a light source to illuminate the optical mask to generate a space-time modulated phase shift fringe light field. Furthermore, the device is introduced into a three-dimensional face imaging system based on phase-shift stripe structured light, so that three-dimensional data of a static or dynamic face target can be acquired. The phase-shift fringe light field pattern projection device can provide higher contrast, higher resolution and faster projection speed, has small installation space requirement and low complexity of the electronic control unit, and can realize system design with low cost and compact structure.
In order to achieve the above object, the present invention provides the following technical solutions:
a three-dimensional imaging system based on arc binary coded phase-shift fringe projection, comprising: an illumination unit (102), an optical mask (103), an optical projection lens (104), an imaging unit (105), a control unit (106) and a three-dimensional reconstruction algorithm module,
the optical mask (103) rotates at a constant speed, and the optical mask (103) is provided with an arc phase shift stripe pattern;
the emergent light emitted by the illumination unit (102) is modulated by rotation of the optical mask (103) to obtain a phase-shift stripe structure light pattern, and the phase-shift stripe structure light pattern is projected onto a target to be detected by the optical projection lens (104);
the control unit (106) is respectively connected with the optical mask (103) and the imaging unit (105) and is used for controlling the rotation speed of the optical mask (103) to be synchronous with the acquisition speed of the imaging unit (105); the control unit (106) is also used for transmitting the projection image sequence which is acquired by the imaging unit (105) and contains the geometric information of the measured object to the three-dimensional reconstruction algorithm module;
the three-dimensional reconstruction algorithm module receives a projection image sequence which is transmitted by the control unit (106) and contains geometric information of the measured target, and realizes three-dimensional reconstruction of the measured target.
As a preferred aspect of the invention, the light source of the lighting unit (102) comprises one or several of the following light sources: LEDs, arc lamps or incandescent lamps.
As a preferred embodiment of the present invention, the photomask (103) is a structured photomask disk, and there is a constant phase shift interval between adjacent arcuate phase shift fringe patterns on the photomask (103).
As a preferable mode of the invention, the optical mask (103) is made of a glass plate, a metal plate or a plastic plate, and the arc phase shift stripe pattern on the optical mask (103) is made on the optical mask (103) by a coating, printing, etching or pasting mode.
As a preferred embodiment of the present invention, the size of the arc-shaped phase-shift stripe pattern on the photomask (103) is determined according to the structural photomask disk r and the number N of the arc-shaped phase-shift stripe patterns, and the arc-directional length of the arc-shaped phase-shift stripe pattern is less than or equal to 2pi r/N.
As a preferable mode of the present invention, the rotation speed f of the photomask (103) m Image acquisition frame rate f depending on imaging unit (105) i And the number N of arc-shaped phase-shift stripe patterns of the photomask (103), and f m ≤f i /N。
As a preferable mode of the present invention, the rotation speed f of the photomask (103) m The value range of (2) is 7.5Hz less than or equal to f m ≤50Hz。
As a preferable scheme of the invention, the photomask (103) performs time modulation integration on the emergent light emitted by the illuminating unit (102) in the rotating motion process, and different light intensities are generated by modulation.
Based on the same conception, a three-dimensional imaging method based on arc binary code phase shift fringe projection is also provided, which is characterized by comprising the following steps:
s1, acquiring a projection image sequence containing geometric information of a measured object by adopting any imaging system;
s2, carrying out polar line correction on a projection image sequence containing geometric information of a measured object to obtain a corrected stripe image;
s3, analyzing texture image information and truncated phase information from the corrected stripe image;
s4, spreading the truncated phase information, and calculating continuous phase information;
s5, utilizing stripe structure light circular arrangement characteristics generated by optical mask modulation to establish a corresponding relation between an absolute phase value and a three-dimensional space cone, combining triangulation principle back projection iteration to solve intersection point coordinates of camera light and the corresponding cone, and calculating three-dimensional geometric data of a measured target.
As a preferred embodiment of the invention, the radius r c The following relation is satisfied with the continuous phase information:
r c ＝r min +φ(r max -r min )
wherein the photomask (103) is circular, r min And r max Is the inner and outer radii, r, of the arcuate phase-shifted fringe pattern on a circular photomask (103) c Is the radius of the circle of the circular photomask (103), and phi is normalized continuous phase information.
Compared with the prior art, the invention has the beneficial effects that:
the invention uses the rotating photomask to generate the space-time modulated arc phase shift fringe light field, and projects the light field to the surface of the object to be detected for coding. Compared with the speckle structure light projection technology, the optical three-dimensional measurement technology based on fringe projection can obtain a three-dimensional reconstruction effect with more excellent performance. Compared with the traditional digital projection, the method can provide higher contrast, higher resolution and faster projection speed, and can realize the system design with compact structure and low cost due to the low complexity of the electronic control unit and small installation space requirement. In addition, the measurement pattern section on the optical mask can be subjected to personalized design according to actual measurement requirements, and the system has strong flexibility; meanwhile, the method has a wide application range, and can meet the high-speed high-precision three-dimensional measurement of dynamic or static face targets.
Description of the drawings:
FIG. 1 is a block diagram of an embodiment of a three-dimensional imaging system based on arc binary coded phase-shift fringe projection in accordance with the present invention;
FIG. 2 is a schematic diagram of a three-dimensional face data acquisition system in which a rotating structured photomask disk is used, according to a block diagram design of an embodiment of the present invention;
FIG. 3 is a schematic diagram of a sequence of error diffusion binary measurement patterns for a photomask according to the present invention;
FIG. 4 is a schematic diagram of a binary measurement pattern sequence for an photomask according to the present invention;
FIG. 5 is a schematic diagram of a progressive binary measurement pattern sequence for an photomask according to the present invention;
FIG. 6 is a schematic diagram of a photomask designed using error diffusion binary measurement patterns according to the present invention;
FIG. 7 is a flow chart of a three-dimensional data acquisition method based on an arc phase-shifted fringe sequence pattern in accordance with an embodiment of the invention;
fig. 8 is a schematic diagram of three-dimensional coordinate point imaging in the case of a monocular system configuration according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to test examples and specific embodiments. It should not be construed that the scope of the above subject matter of the present invention is limited to the following embodiments, and all techniques realized based on the present invention are within the scope of the present invention.
Example 1
Fig. 1 shows a block diagram of an embodiment of a three-dimensional imaging system based on arc binary code phase-shift fringe projection, which uses a face object 100 as a measurement target, and illustrates the structure and working principle of a three-dimensional data acquisition system 101.
As shown in fig. 1, the three-dimensional face data acquisition system 101 mainly includes: an illumination unit 102, an optical mask 103, an optical projection lens 104, an imaging unit 105 of a monocular or binocular camera, and a control unit 106. The illumination unit 102 is used for illuminating the optical mask 103, generating N arc phase shift fringe patterns modulated in time and space, and projecting the N arc phase shift fringe patterns to the surface of the detected face target 100 through the optical projection lens 104, wherein the optical projection lens 104 amplifies and projects the phase fringe structure light patterns to the face surface, so that the face occupies an area of about 1/3 of the whole projection field of view; the imaging unit 105 acquires an image sequence containing geometric information of the measured object 100 after being projected; the control unit 106 is connected to the optical mask 103 and the imaging unit 105, and is configured to control the rotational movement of the optical mask 103 and the synchronous acquisition control between the imaging units 105, and transfer the camera acquired image data to a three-dimensional reconstruction algorithm module (not identified in the figure).
Preferably, the imaging unit 105 is constituted by a monocular or binocular camera, recording a sequence of measurement patterns projected onto the measurement face target (100). Wherein the spatial layout of the camera of the imaging unit and the arc-shaped phase-shift fringe projection unit (102, 103) meets the principle constraint of triangulation.
In an exemplary block diagram, the lighting unit 102 may be a surface light source (e.g., an LED, an arc lamp, an incandescent lamp). The optical mask 103 is placed between the illumination unit 102 and the optical projection lens 104, and is driven by a motor and is rotationally movable around a central rotation axis continuously with an adjustable rotation speed, and the rotation speed of the motor is controlled by a control unit 106. Preferably, the rotating photomask (103) is a structural photomask disc rotating at a constant speed, for example, the rotating speed is 5000rpm, and a constant phase shift interval, namely 2 pi/N, exists between adjacent arc phase shift stripe patterns on the photomask (103), and is fixed on a gear perpendicular to an optical axis, the rotating motion is realized through driving of a gear mechanism, the uniform rotating motion can be continuously carried out around a central rotating shaft at a constant adjustable rotating speed, and the rotating speed of the gear mechanism is controlled by a control unit.
The rotary photomask (103) is made of a glass plate, a metal plate or a plastic plate, and the manufacturing process comprises coating, printing, etching, pasting and the like. The measured pattern segments on the rotating optical mask (103) correspond to the number of projected measured image sequences. The measurement pattern of the rotating photomask (103) is light field modulated by a binary pattern, including but not limited to an error diffusion binary pattern. The measured pattern section of the rotating optical mask (103) has different optical feature surfaces for modulating light, which may be transmittance, reflectance, absorbance or area.
Rotation frequency f of photomask 103 m Image acquisition frame rate f depending on imaging unit 105 i And the number N of arc-shaped phase-shifted fringe patterns of the photomask 103, i.e., according to f m ≤f i and/N. Based on the present embodiment for three-dimensional face dynamic imaging, the rotation frequency f of the photomask 103 m Preferably 30Hz (f i N=120 Hz/4). Image acquisition frame rate f of commonly used imaging unit i The value range is [30Hz,200Hz]Rotation frequency f of the photomask 103 m The value range is [7.5Hz,50Hz]. The imaging unit with higher frame rate can also be selected to match with a motor with high rotating speed for driving the optical mask, so that high-speed three-dimensional imaging is realized. When the motor is set to be at a higher rotating speed, the whole three-dimensional imaging system is a three-dimensional measurement high-speed high-precision three-dimensional imaging system of a dynamic face target.
In another possible embodiment of the present invention, the three-dimensional imaging system 101 may be moved relative to the face object 100 to be measured, so as to acquire three-dimensional data of the object to be measured (e.g., a handheld three-dimensional scanning device) in different views. In addition, the extension of the multi-view three-dimensional imaging system based on the present embodiment should fall within the protection scope of the present invention.
Fig. 2 shows a schematic diagram of a three-dimensional imaging system designed according to an embodiment of the present invention (as shown in fig. 1), in which a rotating photomask disk 203 (patterned on chromed glass) is used to modulate the incident light of an illumination unit 202, in such a way that a spatially and temporally modulated phase-shifted stripe-structured light pattern is generated and projected onto a face object 200 to be measured via an optical projection lens 204, a monocular camera imaging unit 205 acquires a sequence of deformed images modulated by the face shape, and a control unit 206 controls the rotational movement of the photomask disk 203 between the illumination unit 202 and the optical projection lens 204 and the synchronous acquisition of the monocular camera imaging unit 205.
In the embodiment shown in fig. 2, a projection of the rotating photomask disk in the radial direction is used, and the number of etched measurement patterns on the photomask is equal to the number used for three-dimensional imaging patterns. As a result of the rotational movement of the optical mask, the projected measurement pattern has a time-integrating effect in the rotational direction, which can be modulated to generate different intensities during the exposure time of the camera. The arc phase-shifted fringe pattern of the rotating optical mask (103) is located at a radial position on the mask disk and the maximum modulated light intensity is proportional to the arc path of the measured arc phase-shifted fringe pattern, which is equal to the ratio of the light-transmitting arc path to the total arc path.
In addition, the size of the etched measuring pattern (such as a one-dimensional sinusoidal pattern) on the photomask can be adjusted according to the radius r of the mask disc and the number N of the arc phase-shifting stripe patterns, the arc length of the measuring pattern is less than or equal to 2 pi r/N, and the radial length of the measuring pattern is generally recommended to be within the value range of [ r/3,2r/3 ]. The single point resolution of the measurement pattern is finer than existing digital projections, e.g. 2um. In addition, a period of binary coded measuring patterns, such as sine stripe structured light, can be represented by 250 points (pixels), and the number of stripes projected to a target (human face) can be higher than 120 periods and is far higher than 64 periods of the conventional general digital projection, so that high-resolution three-dimensional measurement is realized.
Fig. 3, 4 and 5 show an error diffusion pattern sequence, a binary pattern sequence and a progressive binary pattern sequence, respectively, consisting of four measurement patterns P1, P2, P3, P4. Each measurement pattern has the same dimensions in the radial and axial directions, e.g. 9.6mm, and the measurement patterns are separated by a transition region that is completely opaque, ensuring a smooth transition between the two measurement patterns.
In the embodiment shown in fig. 3, 4 and 5, the photomask has four measurement patterns P i In alternative embodiments, there may be a greater number of measurement patterns, such as 6, 8, or 12.
Fig. 6 shows a photomask designed using error diffusion binary measurement 1 pattern (as shown in fig. 3), with other binary pattern photomask disk designs being similar. Although the binary pattern itself does not have gray scale, in the photomaskDuring the rotation movement of (a) the light (incident light intensity I o ) The time integration is performed to modulate and generate different light intensities I (r). As shown in FIG. 6, the light intensity at each radial position along the circumference of the disk is the light transmission arc length L corresponding to the measurement pattern t And the total length of the inner arc of the exposure time (light-transmitting arc length L) t And an opaque arc length L o ) The ratio of
The modulation direction of the measurement pattern in a cartesian coordinate system is called the main direction H, and the other direction is called the auxiliary direction N (with constant light intensity). FIG. 3 shows different measurement patterns P i A primary direction H and a secondary direction N. FIG. 6 is a diagram of a binary measurement pattern segment P for error diffusion on a rotating photomask disk i A main direction H is given, which in this embodiment extends in a radial direction, and a secondary direction N, which extends in a circumferential direction.
Fig. 7 shows a flow chart of a three-dimensional reconstruction method based on arc phase shift fringe sequence pattern projection, and the specific implementation steps include:
and 700, acquiring three-dimensional face modeling data. The projection device projects a series of stripe structure lights to a human face of a target to be detected, and the monocular or binocular camera acquires stripe sequence images modulated by the three-dimensional geometrical morphology of the human face in real time (taking N=4 as an example): obtaining 8 fringe patterns under the configuration of a binocular camera, wherein 4 cameras are respectively arranged on the left and right; 4 fringe patterns were obtained in a monocular configuration.
Step 701: and carrying out polar correction on the fringe pattern shot by the camera by using a polar geometry technology in combination with system calibration parameters.
Step 702: and analyzing corresponding texture image information and cut-off phase information from the corrected stripe image.
Further, the photographed deformed stripe is expressed as:
wherein (x, y) is the pixel coordinates; r (x, y) is the distribution of the reflectivity of the face surface; a (x, y) is background light intensity, and B (x, y)/A (x, y) represents contrast of stripes; phi (x, y) is the phase information contained in the fringe-structured light field; n is the number of fringe patterns selected for encoding phi (x, y), and the table phase shift times; m (x, y) is embedded modulation information, and the adjacent images are inversely numbered; n is the sequence number of the fringe pattern, and the N-th phase shift is shown in the table, and the value range is 1 to N.
For an N-step phase shift algorithm, the face surface texture image may be generated from the corresponding N stripes. Taking n=4 frame stripe structure light field projection as an example, the formula for calculating the texture image through the stripe map is as follows:
the calculation formula of the truncated phase is as follows:
wherein I is n Represents the stripe diagram of the nth frame, and the value range of n is 1 to 4. As can be seen from equations (3) and (4), embedding the modulation information does not affect the calculation of the texture image and the truncated phase.
The normalized embedded modulation image may be obtained by:
step 703: the embedded modulation image is used to assist in the spreading of the truncated phases, the order k of each truncated phase is obtained, and then the continuous phase information is calculated according to equation (6).
Next, three-dimensional information is acquired under a monocular or binocular camera configuration using the following steps, respectively:
1. in the system configuration of the monocular camera, continuous phase information can be obtained through steps 700-703, and the following steps are used to calculate facial three-dimensional geometry data. Comprising the following steps:
step 704: and establishing a corresponding relation between the absolute phase value and the 3D space cone.
The embodiment of the invention uses a circular photomask disc, and the stripe structure light generated by modulation is arranged in a circular form, namely, the same phase corresponds to a group of concentric circles in a coordinate system of the photomask disc in a continuous phase diagram. If the distortion of the projection lens is ignored, the concentric circles have a one-to-one correspondence with the three-dimensional space cone. The vertex of the cone is positioned at the optical center position O of the projection lens p And the central axis of the cone coincides with the projection lens optical axis (as shown in fig. 8). Given the phase value, combined with the projection lens optical center O p Radius r of optical axis and cone on projection image plane c The cone corresponding to the phase can be determined. Optical center O p The optical axis position can be obtained through system calibration parameters. Radius r c The following relation is satisfied with the normalized continuous phase phi:
r c ＝r min +φ(r max -r min ) (7)
wherein r is min And r max Is the inner and outer radius of the measured pattern on the circular photomask disk.
Step 705: and solving the three-dimensional coordinates through back projection iteration.
For a point of view (x c ,y c ) With a continuous phase phi (x c ,y c ) The intersection point coordinates P (X w ,Y w ,Z w ) (see FIG. 8). Back-projecting the point P into the projection device coordinate system and obtaining the coordinates (phi) in the polar coordinate system p ,r p ) Or coordinates in a Cartesian coordinate system (x p ,y p ). Combining the coordinates obtained by back projection calculation with the optical center O of the projection lens p To the optical axisRadius r of cone on projection image plane p Determining a new cone, and repeating the above process to obtain the intersection point coordinate P' (X) of the camera light and the new cone w ',Y w ',Z w ') until the change in coordinates of the three-dimensional point P between the two iterations (typically measured in terms of euclidean distance) is less than a given threshold. The calculation of the coordinates from the continuous phase to the space three-dimensional point can be completed.
2. In a system configuration of a binocular camera, successive phases in both views of the left and right cameras can be obtained by steps 700-703.
Step 706, unifying the mutually independent relative phase information acquired by the binocular camera by taking the spatial phase unfolding result of the left camera as a reference according to the feature point coordinates acquired by the face feature detection as anchor points according to the texture image, so that the relative phase information acquired by the right camera and the relative phase information acquired by the left camera have the same reference.
Further, the relative phase value of the face feature point is compared with the relative phase value of the face feature point in the right camera space phase expansion result, the difference value of the relative phase values of the face feature points of the left camera and the right camera is obtained, the difference value is divided by 2 pi and is rounded to obtain an integer k, after the k is obtained, the right camera phase diagram is added with 2k pi, the fact that the face feature point is used as an anchor point is achieved, and mutually independent relative phase information obtained by the binocular camera is unified.
Step 707, performing phase matching on the relative phase information of the left and right cameras with unified reference to obtain a parallax map, and calculating a three-dimensional model of the face to be detected according to the parallax map and the system calibration information.
Claims (8)
1. A three-dimensional imaging system based on arc binary coded phase-shift fringe projection, comprising: an illumination unit (102), an optical mask (103), an optical projection lens (104), an imaging unit (105), a control unit (106) and a three-dimensional reconstruction algorithm module,
the optical mask (103) rotates at a constant speed, and the optical mask (103) is provided with an arc phase shift stripe pattern;
the emergent light emitted by the illumination unit (102) is modulated through rotation of the optical mask (103) to obtain a phase-shift stripe structure light pattern, and the phase-shift stripe structure light pattern is projected onto a target to be detected through an optical projection lens (104);
the control unit (106) is respectively connected with the optical mask (103) and the imaging unit (105) and is used for controlling the rotation speed of the optical mask (103) to be synchronous with the acquisition speed of the imaging unit (105); the control unit (106) is further used for transmitting the projection image sequence which is acquired by the imaging unit (105) and contains the geometric information of the measured object to the three-dimensional reconstruction algorithm module;
the three-dimensional reconstruction algorithm module receives the projection image sequence containing the geometric information of the measured object and transmitted by the control unit (106) and realizes the three-dimensional reconstruction of the measured object;
rotational speed f of the photomask (103) m Image acquisition frame rate f depending on imaging unit (105) i And the number N of arc-shaped phase-shift stripe patterns of the photomask (103), and f m ≤f i /N。
2. A three-dimensional imaging system based on arc binary coded phase-shift fringe projection as claimed in claim 1, characterized in that the light source of said illumination unit (102) comprises one or several of the following light sources: LEDs, arc lamps or incandescent lamps.
3. A three-dimensional imaging system based on arc binary coded phase-shift fringe projection as recited in claim 1, wherein said photomask (103) is a structured photomask disk and there is a constant phase-shift spacing between adjacent arc phase-shift fringe patterns on the photomask (103).
4. A three-dimensional imaging system based on arc binary coded phase-shift fringe projection as claimed in claim 3, characterized in that the optical mask (103) is made of a glass plate, a metal plate or a plastic plate, and the arc phase-shift fringe pattern on the optical mask (103) is made on the optical mask (103) by coating, printing, etching or pasting.
5. A three-dimensional imaging system based on arc binary coded phase-shift fringe projection as recited in claim 4, wherein the size of the arc phase-shift fringe pattern on said photomask (103) is determined based on said structured photomask disk r and the number N of arc phase-shift fringe patterns, and the arc directional length of said arc phase-shift fringe pattern is less than or equal to 2rr/N.
6. A three-dimensional imaging system based on arc binary coded phase-shift fringe projection as recited in claim 1, characterized in that the rotational speed f of said photomask (103) m The value range of (2) is 7.5Hz less than or equal to f m ≤50Hz。
7. A three-dimensional imaging system based on arc binary coded phase-shift fringe projection as claimed in any one of claims 1-6, characterized in that said optical mask (103) integrates the time modulation of the outgoing light emitted by said illumination unit (102) during the rotation movement, the modulation generating different light intensities.
8. The three-dimensional imaging method based on arc binary code phase shift fringe projection is characterized by comprising the following steps of:
s1, acquiring a projection image sequence containing geometric information of a measured object by adopting the imaging system as claimed in any one of claims 1 to 7;
s2, carrying out polar line correction on the projection image sequence containing the geometric information of the measured object to obtain a corrected stripe image;
s3, analyzing texture image information and truncated phase information from the corrected stripe image;
s4, expanding the truncated phase information to calculate continuous phase information;
s5, utilizing stripe structure light circular arrangement characteristics generated by optical mask modulation to establish a corresponding relation between an absolute phase value and a three-dimensional space cone, combining a triangulation principle back projection iteration to solve intersection point coordinates of camera light and the corresponding cone, and calculating three-dimensional geometric data of a measured target;
radius of radiusr c The following relation is satisfied with the continuous phase information:
wherein the photomask (103) is circular,r min andr max is the inner radius and outer radius of the arcuate phase-shifted fringe pattern on the circular photomask (103),r c is the radius of the circle of the circular photomask (103),is normalized continuous phase information.
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