CN112082571B - A large-format surveying and mapping camera system and calibration method - Google Patents

Abstract

The invention discloses a large-breadth mapping camera system, which comprises: the system comprises a lens unit, a digital back focal plane unit, an electronics management and control unit and a data storage unit; the lens unit comprises a first multispectral lens, a second multispectral lens, a third multispectral lens, a fourth multispectral lens, a first panchromatic lens, a second panchromatic lens, a third panchromatic lens and a fourth panchromatic lens; the digital back focal plane unit comprises a first multi-spectral digital back, a second multi-spectral digital back, a third multi-spectral digital back, a fourth multi-spectral digital back, a first full-color digital back group, a second full-color digital back group, a third full-color digital back group and a fourth full-color digital back group; the electronics control unit comprises a signal conversion unit and a main control computer. The aerial surveying camera has a large width, and the operation efficiency and the accuracy of the aerial surveying camera are improved.

Description

A large-format surveying and mapping camera system and calibration method

technical field

The invention belongs to the technical field of photoelectric imaging, and in particular relates to a large-format surveying and mapping camera system and a calibration method.

Background technique

Aerial optical mapping is an important technical means to efficiently obtain regional remote sensing information. The large-format surveying and mapping camera can obtain high resolution and wide field of view, improve operation efficiency and save operating costs. At the same time, it is supplemented by slightly lower resolution multispectral images to obtain multispectral information of different spectral bands, which can better serve surveying and mapping applications.

It is an inevitable trend for area array mapping cameras to develop towards ultra-large format. The pixels of 4μm-6μm and the total number of pixels of 800 million to 1.6 billion scale area array mapping can meet the high operation efficiency requirements of wide field of view and high resolution mapping. Restricted by the technological level, it is difficult to realize single-chip CCD or CMOS area array devices with a scale of 30k×30k and 40k×40k. In order to achieve ultra-large-format imaging, area array mapping cameras are generally realized by splicing.

The UtralCamD camera launched by Vexcel in 2003 adopts the mixed splicing method of 4 sets of lenses to achieve large format, requiring 4 sets of lenses to be arranged in a "one" in the flight direction, and each lens corresponds to the back time delay exposure method to obtain a single center projection image . This method must require the lenses to be arranged in a "one" character, and there is a problem of strict constraints on the use of the camera's internal space, and it is difficult to achieve larger-scale splicing when the same device is selected.

The invention patents CN 102883095A and CN 102905061A all use dual lenses and beam splitting prisms to achieve splicing, and there is a 50% energy loss for each image plane, and the beam splitting prism increases the volume weight of the optical system and there is a halo at the image stitching.

SUMMARY OF THE INVENTION

The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, a large-format surveying and mapping camera system and a calibration method are provided, so that the aerial surveying camera can have a large format, and the operation efficiency and accuracy of the aerial surveying and mapping camera are improved.

The object of the present invention is achieved through the following technical solutions: a large-format surveying and mapping camera system, comprising: a lens unit, a digital back focal plane unit, an electronic control unit and a data storage unit; wherein, the lens unit includes a first multispectral lens, second multispectral lens, third multispectral lens, fourth multispectral lens, first panchromatic lens, second panchromatic lens, third panchromatic lens and fourth panchromatic lens; the digital back focus The face unit includes a first multi-spectral digital back, a second multi-spectral digital back, a third multi-spectral digital back, a fourth multi-spectral digital back, a first full-color digital back group, and a second full-color digital back the back group, the third full-color digital back group and the fourth full-color digital back group; the electronic control unit includes a signal conversion unit and a main control computer; wherein, the signal conversion unit and the main control computer are connected; the first The multispectral lens transmits the first optical signal obtained after the object-side scene light is split to the first multispectral digital back; the first multispectral digital back converts the first optical signal into a first electrical signal, and converts the first electrical signal into a first electrical signal. The signal is output to the signal conversion unit, and the signal conversion unit converts the first electrical signal into a first converted optical signal, and transmits the first converted optical signal to the data storage unit; wherein, the first multispectral digital back is behind the first multispectral digital signal. At the position of the focal plane of the lens; the second multispectral lens transmits the second optical signal obtained after the object-side scene light is split to the second multispectral digital back; the second multispectral digital back converts the second optical signal into the second optical signal. two electrical signals, and output the second electrical signal to the signal converting unit, the signal converting unit converts the second electrical signal into a second converted optical signal, and transmits the second converted optical signal to the data storage unit; The spectral digital back is at the focal plane position of the second multi-spectral lens; the third multi-spectral lens transmits the third optical signal obtained after the object-side scene light is split to the third multi-spectral digital back; the third multi-spectral digital back The back converts the third optical signal into a third electrical signal, and outputs the third electrical signal to the signal converting unit, which converts the third electrical signal into a third converted optical signal, and transmits the third converted optical signal to Data storage unit; wherein, the third multi-spectral digital back is at the focal plane position of the third multi-spectral lens; the fourth multi-spectral lens transmits the fourth optical signal obtained after the object-side scene light is split to the fourth multi-spectral digital the back; the fourth multi-spectral digital back converts the fourth optical signal into a fourth electrical signal, and outputs the fourth electrical signal to a signal conversion unit, and the signal conversion unit converts the fourth electrical signal into a fourth converted optical signal, and transmit the fourth converted optical signal to the data storage unit; wherein, the fourth multispectral digital back is at the focal plane position of the fourth multispectral lens; the object-side scene light is transmitted through the first panchromatic lens to obtain the fifth light signal, the fifth optical signal is transmitted to the first full-color digital back group, the first full-color digital back group converts the fifth optical signal into a fifth electrical signal, and outputs the fifth electrical signal to the signal conversion unit, the signal The conversion unit converts the fifth electrical signal into a fifth converted optical signal, and transmits the fifth converted optical signal to the data storage unit; wherein, the first full-color digital back group is located in the area of the first full-color lens. At the position of the focal plane; the object-side scene light is transmitted through the second panchromatic lens to obtain the sixth light signal, and the sixth light signal is transmitted to the second panchromatic digital back group, and the second panchromatic digital back group transmits the sixth light signal. The signal is converted into a sixth electrical signal, and the sixth electrical signal is output to the signal converting unit, the signal converting unit converts the sixth electrical signal into a sixth converted optical signal, and transmits the sixth converted optical signal to the data storage unit; wherein , the second panchromatic digital back group is at the focal plane position of the second panchromatic lens; the object-side scene light is transmitted through the third panchromatic lens to obtain a seventh light signal, and the seventh light signal is transmitted to the third panchromatic digital The back group, the third full-color digital back group converts the seventh optical signal into the seventh electrical signal, and outputs the seventh electrical signal to the signal conversion unit, which converts the seventh electrical signal into the seventh converted light signal, and transmits the seventh converted optical signal to the data storage unit; wherein, the third panchromatic digital back group is located at the focal plane position of the third panchromatic lens; the object-side scene light is transmitted through the fourth panchromatic lens to obtain The eighth optical signal, the eighth optical signal is transmitted to the fourth full-color digital back group, the fourth full-color digital back group converts the eighth optical signal into an eighth electrical signal, and outputs the eighth electrical signal to the signal conversion unit, the signal conversion unit converts the eighth electrical signal into the eighth converted optical signal, and transmits the eighth converted optical signal to the data storage unit; wherein, the fourth full-color digital back group is on the focal plane of the fourth full-color lens location.

In the above large-format surveying and mapping camera system, the optical axis of the first multispectral lens, the optical axis of the second multispectral lens, the optical axis of the third multispectral lens, and the optical axis of the fourth multispectral lens are parallel; The lines connecting the centers of the optical axes form a first square.

In the above large-format surveying and mapping camera system, the optical axis of the first panchromatic lens, the optical axis of the second panchromatic lens, the optical axis of the third panchromatic lens, and the optical axis of the fourth panchromatic lens are parallel; The line connecting the center of the optical axis of , forms a second square; the second square differs from the first square by an angle of 45 degrees.

In the above large-format surveying and mapping camera system, the first full-color digital back group, the second full-color digital back group, the third full-color digital back group, and the fourth full-color digital back group have M rows and N columns in total. back, wherein the number (i, j) of the first full-color digital back group satisfies

mod represents the remainder operation, where i=1, 2..., M; j=1, 2..., N.

In the above large-format surveying and mapping camera system, the first full-color digital back group, the second full-color digital back group, the third full-color digital back group, and the fourth full-color digital back group have M rows and N columns in total. back, wherein the number (i, j) of the second full-color digital back group satisfies

mod represents the remainder operation, where i=1, 2..., M; j=1, 2..., N.

In the above large-format surveying and mapping camera system, the first full-color digital back group, the second full-color digital back group, the third full-color digital back group, and the fourth full-color digital back group have M rows and N columns in total. back, wherein the digital back number (i, j) of the third full-color digital back group satisfies

mod represents the remainder operation, where i=1, 2..., M; j=1, 2..., N.

In the above large-format surveying and mapping camera system, the first full-color digital back group, the second full-color digital back group, the third full-color digital back group, and the fourth full-color digital back group have M rows and N columns in total. back, wherein the number (i, j) of the fourth full-color digital back group satisfies

mod represents the remainder operation, where i=1, 2..., M; j=1, 2..., N.

A panchromatic camera calibration method, comprising the following steps: Step 1: respectively establishing the focal planes of four panchromatic lenses of a first panchromatic lens, a second panchromatic lens, a third panchromatic lens and a fourth panchromatic lens Virtual imaging grid, the virtual imaging grid is M rows and N columns, and the corresponding grid pixel number is [M(m-Δm)+Δm]×[N(n-Δn)+Δn]; among them, M is participating in splicing The number of rows of full-color digital backs, N is the number of columns participating in the splicing of full-color digital backs, m is the row number of full-color digital back pixels, and n is the number of columns of full-color digital back pixels , Δm is the number of overlapping pixels in the horizontal direction in splicing, Δn is the number of overlapping pixels in the vertical direction in splicing; Step 2: Rename the pixels of the panchromatic digital back group at the focal plane positions of the four panchromatic lenses; step 3: Perform the calibration of the internal orientation elements of the single camera on the panchromatic camera corresponding to each panchromatic lens to obtain the principal point and principal distance of the panchromatic single camera; among them, the first panchromatic lens corresponding to the first panchromatic lens Camera principal point (x ₁₀ , y ₁₀ ), principal distance f ₁ ; the second panchromatic camera principal point (x ₂₀ , y ₂₀ ) corresponding to the second panchromatic lens, principal distance f ₂ ; the third panchromatic lens corresponds to the principal point of the third panchromatic camera (x ₃₀ , y ₃₀ ) and the principal distance f ₃ ; the principal point of the fourth panchromatic camera corresponding to the fourth panchromatic lens (x ₄₀ , y ₄₀ ) and the principal distance f ₄ ; Step 4: Establish image space coordinate system S _i -x _i y _i z for the first panchromatic camera, the second panchromatic camera, the third panchromatic camera and the fourth panchromatic camera and the four panchromatic cameras respectively _i , where i=1, 2, 3, 4 represents the i-th panchromatic camera; in the coordinate system S _i -x _i y _{i zi} , the coordinate origin is the camera site S _i of each panchromatic camera, which is the same as the i-th panchromatic camera. The axis parallel to the horizontal direction of the full color digital back pixel of the color camera is the x _i axis, and the axis parallel to the vertical direction of the full color digital back pixel of the ith panchromatic camera is the y _i axis. The axis parallel to the axis is the z _i axis; Step 5: Establish a virtual ground auxiliary coordinate system O-XYZ, where O is the vertical projection of the first panchromatic camera camera station S1 _on the ground, and the first panchromatic camera image The axis parallel to the x ₁ axis of the space coordinate system S ₁ -x ₁ y ₁ z ₁ is the X axis, and the axis parallel to the y ₁ axis of the first panchromatic camera image space coordinate system S ₁ -x ₁ y ₁ z ₁ is the Y axis, and the axis parallel to the z ₁ axis of the first panchromatic camera image space coordinate system S ₁ -x ₁ y ₁ z ₁ is the Z axis; Step 6: Obtain the second panchromatic camera and the third panchromatic camera. The rotation matrix of the color camera and the fourth panchromatic camera relative to the first panchromatic camera is R _i , i=2, 3, 4; Step 7: Take the first panchromatic camera image space coordinate system S ₁ -x ₁ y ₁ z ₁ is the virtual phase space coordinate system, and the pixels of the panchromatic digital back group at the focal plane positions of the second panchromatic camera, the third panchromatic camera and the fourth panchromatic camera are directed to S ₁ -x ₁ y ₁ z ₁ for virtual image ordering Center projection transformation.

In the above panchromatic camera calibration method, in step 6, the rotation matrix R _i is:

Among them, a _i1 , a _i2 , a _i3 , b _i1 , b _i2 , b _i3 , c _i1 , c _i2 , and c _i3 are rotation matrix parameters.

In the above-mentioned full-color camera calibration method, in step 7, the conversion formula is as follows:

Among them, i=2, 3, 4, the coordinates of the point to be converted (x _i , y _i ) in the S _i -x _i y _i z _i coordinate system of the i-th panchromatic camera, and x _i is S _i -x _i y The abscissa and y _i of the pixel in the _{i zi} coordinate system are the ordinate of the pixel in the S _i -x _i y _i z _i coordinate system; (x _i , y _i ) is converted to S ₁ -x ₁ of the first panchromatic camera Coordinate (x ₀ , y ₀ ) in the y ₁ z ₁ coordinate system, x ₀ is the abscissa of the pixel in the S ₁ -x ₁ y ₁ z ₁ coordinate system, and y ₀ is in the S ₁ -x ₁ y ₁ z ₁ coordinate system Pixel ordinate; X _i is the abscissa of the _i -th panchromatic camera’s camera station Si in the virtual ground auxiliary coordinate system O-XYZ, and Y _i is the _i -th panchromatic camera’s camera station Si in the virtual ground auxiliary coordinate system The ordinate in the coordinate system O-XYZ, Z _i is the vertical coordinate of the camera site Si of the _ith panchromatic camera in the virtual ground auxiliary coordinate system O-XYZ; Z ₁ is the camera site of the first panchromatic camera The vertical coordinate of S ₁ in the virtual ground auxiliary coordinate system O-XYZ; f _i is the principal distance of the ith panchromatic camera, and f ₁ is the principal distance of the first panchromatic camera.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The present invention adopts a multi-lens and multi-imaging device with parallel main optical axes, which is a hybrid splicing imaging system of internal and external fields of view, which can realize an ultra-large-format aerial survey camera system and improve the operation efficiency and accuracy of the aerial survey and mapping camera;

(2) The center of the optical axis of the lens of the present invention is arranged in a square, the structural layout of panchromatic and multi-hyperspectral is optimized, the size of the outer envelope of the structure is reduced to the greatest extent, and the utilization rate of the structure space is improved;

(3) The present invention adopts parallel-serial signal conversion, electro-optical, photoelectric signal conversion, etc., to reduce the number of cables in the camera system, optimize the structural layout and facilitate engineering implementation;

(4) The present invention determines the calibration process of the panchromatic camera and provides the conversion method of the virtual single-center image, realizes the output of the approximate single-center image, and is compatible with the existing aerial survey data processing software interface.

Description of drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are for the purpose of illustrating preferred embodiments only and are not to be considered limiting of the invention. Also, the same components are denoted by the same reference numerals throughout the drawings. In the attached image:

1 is an overall block diagram of a large-format surveying and mapping camera system provided by an embodiment of the present invention;

2 is a schematic diagram of a positional placement relationship of a panchromatic lens provided by an embodiment of the present invention;

3 is a bottom view of a panchromatic lens and a multispectral lens provided by an embodiment of the present invention;

4 is a schematic diagram of a digital back group corresponding to a panchromatic lens provided by an embodiment of the present invention;

5 is a schematic diagram of parallel-serial conversion of 4-channel signals provided by an embodiment of the present invention into 1-channel signal;

6 is a flowchart of a camera calibration method provided by an embodiment of the present invention;

7 is a schematic diagram of the definition of a pixel sequence number at a camera focal plane provided by an embodiment of the present invention;

FIG. 8 is a schematic diagram of a space coordinate system provided by an embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be more thoroughly understood, and will fully convey the scope of the present disclosure to those skilled in the art. It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

FIG. 1 is an overall block diagram of a large-format surveying and mapping camera system provided by an embodiment of the present invention. As shown in Figure 1, the large-format surveying and mapping camera system includes: a lens unit, a digital back focal plane unit, an electronic control unit and a data storage unit; wherein,

The lens unit includes a first multispectral lens, a second multispectral lens, a third multispectral lens, a fourth multispectral lens, a first panchromatic lens, a second panchromatic lens, a third panchromatic lens, and a fourth panchromatic lens ;

The digital back focal plane unit includes a first multi-spectral digital back, a second multi-spectral digital back, a third multi-spectral digital back, a fourth multi-spectral digital back, a first full-color digital back group, a second multi-spectral digital back Full color digital back group, third full color digital back group and fourth full color digital back group;

The first multispectral lens transmits the first optical signal obtained after the object-side scene light is split to the first multispectral digital back; the first multispectral digital back converts the first optical signal into a first electrical signal, and converts the first optical signal into a first electrical signal. An electrical signal is output to the signal conversion unit, the signal conversion unit converts the first electrical signal into a first converted optical signal, and transmits the first converted optical signal to the data storage unit; wherein the first multispectral digital back at the focal plane position of the multispectral lens;

The second multi-spectral lens transmits the second optical signal obtained after the object-side scene light is split to the second multi-spectral digital back; the second multi-spectral digital back converts the second optical signal into a second electrical signal, and converts the The two electrical signals are output to the signal conversion unit, and the signal conversion unit converts the second electrical signal into a second converted optical signal, and transmits the second converted optical signal to the data storage unit; wherein the second multispectral digital back is located in the second at the focal plane position of the multispectral lens;

The third multi-spectral lens transmits the third optical signal obtained after the object-side scene light is split to the third multi-spectral digital back; the third multi-spectral digital back converts the third optical signal into a third electrical signal, and converts the third The three electrical signals are output to the signal conversion unit, and the signal conversion unit converts the third electrical signal into a third converted optical signal, and transmits the third converted optical signal to the data storage unit; wherein, the third multispectral digital back is in the third at the focal plane position of the multispectral lens;

The fourth multi-spectral lens transmits the fourth optical signal obtained after the object-side scene light is split to the fourth multi-spectral digital back; the fourth multi-spectral digital back converts the fourth optical signal into a fourth electrical signal, and converts the fourth The four electrical signals are output to the signal conversion unit, and the signal conversion unit converts the fourth electrical signal into a fourth converted optical signal, and transmits the fourth converted optical signal to the data storage unit; wherein, the fourth multispectral digital back is in the fourth at the focal plane position of the multispectral lens;

The four multispectral lenses use the same optical design parameters and the same lens structure design parameters; the optical axes of the four multispectral lenses are parallel, and the center of the optical axis is a fixed point to form a square.

The 4 multispectral digital backs are the same, and the number of pixels in each back is m'×n'.

The object-side scene light is transmitted through the first panchromatic lens to obtain a fifth light signal, and the fifth light signal is transmitted to the first panchromatic digital back group, and the first panchromatic digital back group converts the fifth light signal into a fifth light signal. electrical signal, and output the fifth electrical signal to the signal conversion unit, the signal conversion unit converts the fifth electrical signal into a fifth converted optical signal, and transmits the fifth converted optical signal to the data storage unit; wherein the first full-color The digital back group is at the focal plane position of the first panchromatic lens; the first panchromatic digital back group, the second panchromatic digital back group, the third panchromatic digital back group and the fourth panchromatic digital back group The group has a total of M rows and N columns of backs, wherein, the digital back number (i, j) of the first full-color digital back group satisfies

mod represents the remainder operation, where i=1, 2..., M; j=1, 2..., N.

The object-side scene light is transmitted through the second panchromatic lens to obtain a sixth light signal, the sixth light signal is transmitted to the second panchromatic digital back group, and the second panchromatic digital back group converts the sixth light signal into a sixth light signal. electrical signal, and output the sixth electrical signal to the signal conversion unit, the signal conversion unit converts the sixth electrical signal into a sixth converted optical signal, and transmits the sixth converted optical signal to the data storage unit; wherein, the second full-color The digital back group is at the focal plane position of the second panchromatic lens; the first panchromatic digital back group, the second panchromatic digital back group, the third panchromatic digital back group and the fourth panchromatic digital back group The group has a total of M rows and N columns of backs, wherein the number (i, j) of the second full-color digital back group satisfies

mod represents the remainder operation, where i=1, 2..., M; j=1, 2..., N.

The object-side scene light is transmitted through the third panchromatic lens to obtain the seventh light signal, the seventh light signal is transmitted to the third panchromatic digital back group, and the third panchromatic digital back group converts the seventh light signal into the seventh light signal electrical signal, and output the seventh electrical signal to the signal conversion unit, the signal conversion unit converts the seventh electrical signal into the seventh converted optical signal, and transmits the seventh converted optical signal to the data storage unit; wherein, the third full-color The digital back group is at the focal plane position of the third panchromatic lens; the first panchromatic digital back group, the second panchromatic digital back group, the third panchromatic digital back group and the fourth panchromatic digital back group The group has a total of M rows and N columns of backs, among which, the digital back number (i, j) of the third full-color digital back group satisfies

mod represents the remainder operation, where i=1, 2..., M; j=1, 2..., N.

The object-side scene light is transmitted through the fourth panchromatic lens to obtain the eighth light signal, and the eighth light signal is transmitted to the fourth panchromatic digital back group, which converts the eighth light signal into the eighth light signal. electrical signal, and output the eighth electrical signal to the signal conversion unit, the signal conversion unit converts the eighth electrical signal into the eighth converted optical signal, and transmits the eighth converted optical signal to the data storage unit; wherein, the fourth full color The digital back group is at the focal plane position of the fourth panchromatic lens; the first panchromatic digital back group, the second panchromatic digital back group, the third panchromatic digital back group and the fourth panchromatic digital back group The group has a total of M rows and N columns of backs, where the number (i, j) of the fourth full-color digital back group satisfies

mod represents the remainder operation, where i=1, 2..., M; j=1, 2..., N.

As shown in Figure 2, the four panchromatic lenses use the same optical design parameters and the same lens structure design parameters; the optical axes of the four panchromatic lenses are parallel, and the center of the optical axis is a fixed point to form a square.

The optical axis center of the four multispectral lenses is a square formed by a fixed point, and the optical axis center of the four panchromatic lenses is a square formed by a fixed point, and the two squares differ by an angle of 45 degrees (as shown in Figure 3).

The full-color digital backs in M rows and N columns are the same, and the number of pixels in each back is m×n.

The positions of the 4 full-color digital back groups corresponding to the 4 full-color lenses are interchangeable.

信号转换器和；其中[]表示向上取整数。The signal conversion unit includes a first signal converter, a second signal converter, a third signal converter, a fourth signal converter, ...

Signal converter sum; where [] represents an integer rounded up.

The first signal converter receives the electrical signals of the 4 digital backs, the electrical signals of the 4-way synchronous exposure digital backs are input to the signal converter in parallel, and the signal converter outputs the optical signal serially;

The second signal converter receives the electrical signals of the 4 digital backs, the electrical signals of the 4-way synchronous exposure digital backs are input to the signal converter in parallel, and the signal converter outputs the optical signal serially;

…….

信号转换器接收4个数字后背的电信号，4路同步曝光数字后背的电信号并行输入到信号转换器，信号转换器串行输出光信号。其中[]表示向上取整数；the first

The signal converter receives the electrical signals of the 4 digital backs, and the electrical signals of the 4-way synchronous exposure digital backs are input to the signal converter in parallel, and the signal converter outputs the optical signal serially. Where [] means rounding up an integer;

信号转换器接收剩余数字后背的电信号，剩余路同步曝光数字后背的电信号并行输入到信号转换器，信号转换器串行输出光信号。其中[]表示向上取整数；the first

The signal converter receives the electrical signals of the remaining digital backs, the electrical signals of the remaining synchronous exposure digital backs are input to the signal converter in parallel, and the signal converters output optical signals serially. Where [] means rounding up an integer;

The signal converter includes a control chip, a memory chip and an electro-optical signal conversion chip. The control chip is a common chip such as FPGA or DSP; the memory chip is a common chip such as SDRAM; the function of the electro-optical signal conversion chip is to convert the electrical signal into an optical fiber signal output;

The electrical signal of the digital back is a common signal format such as Camera Link format or USB3.0 format.

The main control computer sends control instructions to the signal converter control chip, and receives feedback information from the signal converter control chip;

The data storage unit receives the optical fiber signal output by the signal converter, converts the optical signal into an electrical signal through the photoelectric signal conversion chip in the data storage unit, and stores it in the data storage disk array.

Further, the characteristic relationship between the number of digital backs corresponding to the panchromatic lens is: as shown in Figure 4, after the panchromatic lens corresponds to the digital back imaging, there are M×N (M rows and N columns) digital backs corresponding to a specific stitching position relationship. , divide the M×N digital backs into four groups: group 1 digital back number (i, j), where i mod 4=1 or 3 (i mod 4=1 means that i is divided by 4 and the remainder is 1), j mod 4 = 1 or 3; group 2 digit back number (i, j), where i mod 4 = 1 or 3, j mod 4 = 0 or 2; group 3 digit back number (i, j), where i mod 4 = 0 or 2, j mod 4 = 1 or 3; group 4 numeric back numbers (i, j), where i mod 4 = 0 or 2, j mod 4 = 0 or 2. 4 groups of numeric backs It is installed correspondingly with the four groups of panchromatic lenses, and the positions are interchangeable.

The electronic control unit and the data storage unit realize the camera system control and data storage functions. Among them, the electronic control unit mainly includes a main control computer and a signal converter. The main control computer receives and processes information instructions. Every 4 digital backs corresponds to a signal converter. The signal converter realizes 4-channel electronics for synchronous and parallel reception. The image data signal is converted into a serial output optical fiber image data signal, and the optical fiber image data signal is output to the data storage unit to complete the data storage.

As shown in Figure 5, 4 channels of synchronous exposure electronic image data signals are simultaneously input to the signal converter, and the electronic image data signals are in common signal formats such as Camera Link format or USB3.0 format. The control chip in the signal converter controls and simultaneously receives four signals, and stores them in the memory chip. The control chip is a common chip such as FPGA or DSP. The control chip receives the instructions of the main control computer, and serially outputs the 4-channel signals to the electro-optical signal conversion device. Signal conversion device, the function of photoelectric signal conversion device is to convert optical signals into electrical signals and store them in the data storage disk array.

Aiming at the calibration of the camera system, a calibration method of the large-format surveying and mapping camera system is proposed, which includes multi-spectral camera calibration and panchromatic camera calibration. The camera calibration process is shown in Figure 6. Multi-spectral camera calibration is a routine calibration method, and precision goniometric methods can be used.

The full-color camera calibration method includes the following steps:

Step 1: Create virtual imaging grids at the focal planes of the first panchromatic lens, the second panchromatic lens, the third panchromatic lens, and the fourth panchromatic lens, respectively, as shown in Figure 7. The virtual imaging grid is M rows and N columns, and the corresponding grid pixel number is [M(m-Δm)+Δm]×[N(n-Δn)+Δn].

Among them, M is the number of rows involved in splicing the number of full-color digital backs, N is the number of columns involved in splicing the number of full-color digital backs, m is the number of rows of pixels in the full-color digital back, and n is the full-color digital back. The number of back pixel number columns, Δm is the number of overlapping pixels in the horizontal direction in the mosaic, and Δn is the number of overlapping pixels in the vertical direction in the mosaic.

The focal plane of each panchromatic camera is a "real" pixel, and the number of "real" digital back pixels needs to be renamed, such as the (A, B)th digital back, that is, at row A, column B Digital back, whose first pixel at the focal plane of the panchromatic camera is named ((A-1)m-(A-2)Δm+1,(B-1)n-(B-2)Δm+1 ).

Step 2: Rename the pixels of the panchromatic digital back at the focal plane of the 4 panchromatic lenses. As shown in Figure 7, the number of panchromatic digital back pixels at row A, column B at the focal plane of the panchromatic lens is renamed as follows, and its pixel (i, j) is renamed as ((A-1)m- (A-2)Δm+i, (B-1)n-(B-2)Δn+j). where i is the number of original pixel rows, and j is the number of original pixel columns;

Step 3: Perform a single-camera orientation element calibration on the four panchromatic cameras respectively, and obtain the distortion, principal point, and principal distance parameters of the panchromatic single-camera. The first panchromatic camera principal point (x ₁₀ , y ₁₀ ), the principal distance f ₁ ; the second panchromatic camera principal point (x ₂₀ , y ₂₀ ), the principal distance f ₂ ; the third panchromatic camera principal point (x ₃₀ , y ₃₀ ), principal distance f ₃ ; fourth panchromatic camera principal point (x ₄₀ , y ₄₀ ), principal distance f ₄ .

Step 4: Establish image space coordinate system S _i -x _i y _i z for the first panchromatic camera, the second panchromatic camera, the third panchromatic camera and the fourth panchromatic camera and the four panchromatic cameras respectively _i , where i=1, 2, 3, 4 represents the i-th panchromatic camera; in the coordinate system S _i -x _i y _{i zi} , the coordinate origin is the camera site S _i of each panchromatic camera, which is the same as the i-th panchromatic camera. The axis parallel to the horizontal direction of the full color digital back pixel of the color camera is the x _i axis, and the axis parallel to the vertical direction of the full color digital back pixel of the ith panchromatic camera is the y _i axis. The axis parallel to the axis is the _zi axis, as shown in Figure 8.

Step 5: Establish a virtual ground auxiliary coordinate system O-XYZ, where O is the vertical projection of the first panchromatic camera camera station S ₁ on the ground, and the first panchromatic camera image space coordinate system S ₁ -x ₁ y The axis parallel to the x ₁ axis of ₁ z ₁ is the X axis, and the axis parallel to the y ₁ axis of the first panchromatic camera image space coordinate system S ₁ -x ₁ y ₁ z ₁ is the Y axis, which is the same as the first panchromatic camera. The axis parallel to the z ₁ axis of the color camera image space coordinate system S ₁ -x ₁ y ₁ z ₁ is the Z axis.

Step 6: Obtain the relative outer azimuth elements of the second panchromatic camera, the third panchromatic camera, and the fourth panchromatic camera relative to the first panchromatic camera respectively. The rotation matrices of the second panchromatic camera, the third panchromatic camera, and the fourth panchromatic camera relative to the first panchromatic camera are obtained as Ri, _i =2,3,4. R _i is expressed as:

where a _i1 , a _i2 , a _i3 , b _i1 , b _i2 , b _i3 , c _i1 , c _i2 , and c _i3 are rotation matrix parameters.

Step 7: Take the first panchromatic camera image space coordinate system S ₁ -x ₁ y ₁ z ₁ as the virtual phase space coordinate system, the second panchromatic camera, the third panchromatic camera and the fourth panchromatic camera The pixels of the panchromatic digital back group at the position of the focal plane are converted to S ₁ -x ₁ y ₁ z ₁ by the single-center projection of the virtual image. The conversion formula is as follows:

Among them, i=2, 3, 4, the coordinates of the point to be converted (x _i , y _i ) in the S _i -x _i y _i z _i coordinate system of the i-th panchromatic camera, and x _i is S _i -x _i y The abscissa and y _i of the pixel in the _{i zi} coordinate system are the ordinate of the pixel in the S _i -x _i y _i z _i coordinate system; (x _i , y _i ) is converted to S ₁ -x ₁ of the first panchromatic camera Coordinate (x ₀ , y ₀ ) in the y ₁ z ₁ coordinate system, x ₀ is the abscissa of the pixel in the S ₁ -x ₁ y ₁ z ₁ coordinate system, and y ₀ is in the S ₁ -x ₁ y ₁ z ₁ coordinate system pixel ordinate;

X _i is the abscissa of the _i -th panchromatic camera's camera station Si in the virtual ground auxiliary coordinate system O-XYZ, and Y _i is the _ith panchromatic camera's camera station Si in the virtual ground auxiliary coordinate system O-XYZ The vertical coordinate in XYZ, Z _i is the vertical coordinate of the imaging station S _i of the i-th panchromatic camera in the virtual ground auxiliary coordinate system O-XYZ;

Z ₁ is the vertical coordinate of the photographing point S ₁ of the first panchromatic camera in the virtual ground auxiliary coordinate system O-XYZ;

f _i is the principal distance of the i-th panchromatic camera, and f ₁ is the principal distance of the first panchromatic camera.

The present invention adopts the multi-lens and multi-imaging device with parallel main optical axis and the internal and external field of view mixed splicing imaging system, which can realize the ultra-large-scale aerial survey camera system and improve the operation efficiency and accuracy of the aerial survey and mapping camera; the optical axis center of the present invention is arranged squarely, The structure layout of panchromatic and multi-hyperspectral is optimized, the size of the outer envelope of the structure is minimized, and the utilization rate of the structure space is improved; the present invention adopts parallel-serial signal conversion, electro-optical, electro-optical signal conversion, etc., to reduce the number of camera system cables, optimize The structure layout is convenient for engineering realization; the invention determines the calibration flow of the panchromatic camera and provides the conversion method of the virtual single-center image, realizes the output of the approximate single-center image, and is compatible with the existing aerial survey data processing software interface.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can use the methods and technical contents disclosed above to improve the present invention without departing from the spirit and scope of the present invention. The technical solutions are subject to possible changes and modifications. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention belong to the technical solutions of the present invention. protected range.

Claims (3)

1. a full-color camera calibration method, is characterized in that comprising the steps: Step 1: Establish virtual imaging grids at the focal planes of the first panchromatic lens, the second panchromatic lens, the third panchromatic lens and the fourth panchromatic lens, respectively, and the virtual imaging grid is M rows and N column, the corresponding grid pixel number is [M(m-Δm)+Δm]×[N(n-Δn)+Δn]; Among them, M is the number of rows involved in splicing the number of full-color digital backs, N is the number of columns involved in splicing the number of full-color digital backs, m is the number of rows of pixels in the full-color digital back, and n is the full-color number The number of pixels in the back, Δm is the number of overlapping pixels in the horizontal direction in splicing, and Δn is the number of overlapping pixels in the vertical direction in splicing; Step 2: Rename the pixels of the panchromatic digital back group at the focal plane positions of the 4 panchromatic lenses; Step 3: Perform a single-camera orientation element calibration on the panchromatic camera corresponding to each panchromatic lens to obtain the principal point and principal distance of the panchromatic single camera; wherein, the first panchromatic lens corresponding to the first panchromatic lens Principal point (x ₁₀ , y ₁₀ ), principal distance f ₁ of the color camera; principal point of the second panchromatic camera corresponding to the second panchromatic lens (x ₂₀ , y ₂₀ ), principal distance f ₂ ; the third panchromatic lens The corresponding principal point of the third panchromatic camera (x ₃₀ , y ₃₀ ), the principal distance f ₃ ; the principal point of the fourth panchromatic camera corresponding to the fourth panchromatic lens (x ₄₀ , y ₄₀ ), the principal distance f ₄ ; Step 4: Establish image space coordinate system S _i -x _i y _i z for the first panchromatic camera, the second panchromatic camera, the third panchromatic camera and the fourth panchromatic camera and the four panchromatic cameras respectively _i , where i=1, 2, 3, 4 represents the i-th panchromatic camera; in the coordinate system S _i -x _i y _{i zi} , the coordinate origin is the camera site S _i of each panchromatic camera, which is the same as the i-th panchromatic camera. The axis parallel to the horizontal direction of the full color digital back pixel of the color camera is the x _i axis, and the axis parallel to the vertical direction of the full color digital back pixel of the ith panchromatic camera is the y _i axis. The axis parallel to the axis is the _zi axis; Step 5: Establish a virtual ground auxiliary coordinate system O-XYZ, where O is the vertical projection of the first panchromatic camera camera station S ₁ on the ground, and the first panchromatic camera image space coordinate system S ₁ -x ₁ y The axis parallel to the x ₁ axis of ₁ z ₁ is the X axis, and the axis parallel to the y ₁ axis of the first panchromatic camera image space coordinate system S ₁ -x ₁ y ₁ z ₁ is the Y axis, which is the same as the first panchromatic camera. The axis parallel to the z ₁ axis of the color camera image space coordinate system S ₁ -x ₁ y ₁ z ₁ is the Z axis; Step 6: Obtain the rotation matrix of the second panchromatic camera, the third panchromatic camera, and the fourth panchromatic camera relative to the first panchromatic camera as R _i , i=2,3,4; Step 7: Take the first panchromatic camera image space coordinate system S ₁ -x ₁ y ₁ z ₁ as the virtual phase space coordinate system, the second panchromatic camera, the third panchromatic camera and the fourth panchromatic camera The pixels of the full-color digital back group at the position of the focal plane are converted to S ₁ -x ₁ y ₁ z ₁ by the single-center projection of the virtual image; wherein, The large-format surveying and mapping camera system includes: a lens unit, a digital back focal plane unit, an electronic control unit and a data storage unit; wherein, The lens unit includes a first multispectral lens, a second multispectral lens, a third multispectral lens, a fourth multispectral lens, a first panchromatic lens, a second panchromatic lens, a third panchromatic lens, and a fourth panchromatic lens. color lens; The digital back focal plane unit includes a first multi-spectral digital back, a second multi-spectral digital back, a third multi-spectral digital back, a fourth multi-spectral digital back, a first full-color digital back group, The second full-color digital back group, the third full-color digital back group and the fourth full-color digital back group; The electronic control unit includes a signal conversion unit and a main control computer; wherein, the signal conversion unit is connected with the main control computer; The first multispectral lens transmits the first optical signal obtained after the object-side scene light is split to the first multispectral digital back; the first multispectral digital back converts the first optical signal into a first electrical signal, and converts the first optical signal into a first electrical signal. An electrical signal is output to the signal conversion unit, the signal conversion unit converts the first electrical signal into a first converted optical signal, and transmits the first converted optical signal to the data storage unit; wherein the first multispectral digital back at the focal plane position of the multispectral lens; The second multi-spectral lens transmits the second optical signal obtained after the object-side scene light is split to the second multi-spectral digital back; the second multi-spectral digital back converts the second optical signal into a second electrical signal, and converts the The two electrical signals are output to the signal conversion unit, and the signal conversion unit converts the second electrical signal into a second converted optical signal, and transmits the second converted optical signal to the data storage unit; wherein the second multispectral digital back is located in the second at the focal plane position of the multispectral lens; The third multi-spectral lens transmits the third optical signal obtained after the object-side scene light is split to the third multi-spectral digital back; the third multi-spectral digital back converts the third optical signal into a third electrical signal, and converts the third The three electrical signals are output to the signal conversion unit, and the signal conversion unit converts the third electrical signal into a third converted optical signal, and transmits the third converted optical signal to the data storage unit; wherein, the third multispectral digital back is in the third at the focal plane position of the multispectral lens; The fourth multi-spectral lens transmits the fourth optical signal obtained after the object-side scene light is split to the fourth multi-spectral digital back; the fourth multi-spectral digital back converts the fourth optical signal into a fourth electrical signal, and converts the fourth The four electrical signals are output to the signal conversion unit, and the signal conversion unit converts the fourth electrical signal into a fourth converted optical signal, and transmits the fourth converted optical signal to the data storage unit; wherein, the fourth multispectral digital back is in the fourth at the focal plane position of the multispectral lens; The object-side scene light is transmitted through the first panchromatic lens to obtain a fifth light signal, and the fifth light signal is transmitted to the first panchromatic digital back group, and the first panchromatic digital back group converts the fifth light signal into a fifth light signal. electrical signal, and output the fifth electrical signal to the signal conversion unit, the signal conversion unit converts the fifth electrical signal into a fifth converted optical signal, and transmits the fifth converted optical signal to the data storage unit; wherein the first full-color The digital back group is at the focal plane position of the first panchromatic lens; The object-side scene light is transmitted through the second panchromatic lens to obtain a sixth light signal, the sixth light signal is transmitted to the second panchromatic digital back group, and the second panchromatic digital back group converts the sixth light signal into a sixth light signal. electrical signal, and output the sixth electrical signal to the signal conversion unit, the signal conversion unit converts the sixth electrical signal into a sixth converted optical signal, and transmits the sixth converted optical signal to the data storage unit; wherein, the second full-color The digital back group is at the focal plane position of the second panchromatic lens; The object-side scene light is transmitted through the third panchromatic lens to obtain the seventh light signal, the seventh light signal is transmitted to the third panchromatic digital back group, and the third panchromatic digital back group converts the seventh light signal into the seventh light signal electrical signal, and output the seventh electrical signal to the signal conversion unit, the signal conversion unit converts the seventh electrical signal into the seventh converted optical signal, and transmits the seventh converted optical signal to the data storage unit; wherein, the third full-color The digital back group is at the focal plane position of the third panchromatic lens; The object-side scene light is transmitted through the fourth panchromatic lens to obtain the eighth light signal, and the eighth light signal is transmitted to the fourth panchromatic digital back group, which converts the eighth light signal into the eighth light signal. electrical signal, and output the eighth electrical signal to the signal conversion unit, the signal conversion unit converts the eighth electrical signal into the eighth converted optical signal, and transmits the eighth converted optical signal to the data storage unit; wherein, the fourth full color The digital back group is at the focal plane position of the fourth panchromatic lens. 2. panchromatic camera calibration method according to claim 1, is characterized in that: in step 6, the rotation matrix is that R _i is:

Among them, a _i1 , a _i2 , a _i3 , b _i1 , b _i2 , b _i3 , c _i1 , c _i2 , and c _i3 are rotation matrix parameters. 3. panchromatic camera calibration method according to claim 1, is characterized in that: in step 7, conversion formula is as follows:

Among them, i=2, 3, 4, the coordinates of the point to be converted (x _i , y _i ) in the S _i -x _i y _i z _i coordinate system of the i-th panchromatic camera, and x _i is S _i -x _i y The abscissa and y _i of the pixel in the _{i zi} coordinate system are the ordinate of the pixel in the S _i -x _i y _i z _i coordinate system; (x _i , y _i ) is converted to S ₁ -x ₁ of the first panchromatic camera Coordinate (x ₀ , y ₀ ) in the y ₁ z ₁ coordinate system, x ₀ is the abscissa of the pixel in the S ₁ -x ₁ y ₁ z ₁ coordinate system, and y ₀ is in the S ₁ -x ₁ y ₁ z ₁ coordinate system Pixel ordinate; X _i is the abscissa of the _i -th panchromatic camera’s camera station Si in the virtual ground auxiliary coordinate system O-XYZ, and Y _i is the _i -th panchromatic camera’s camera station Si in the virtual ground auxiliary coordinate system The ordinate in the coordinate system O-XYZ, Z _i is the vertical coordinate of the camera site Si of the _ith panchromatic camera in the virtual ground auxiliary coordinate system O-XYZ; Z ₁ is the camera site of the first panchromatic camera The vertical coordinate of S ₁ in the virtual ground auxiliary coordinate system O-XYZ; f _i is the principal distance of the ith panchromatic camera, and f ₁ is the principal distance of the first panchromatic camera.

Images