JPH05203490A - Imaging type radiation meter with interband resistoration function - Google Patents

Abstract

PURPOSE:To obtain an imaging type radiation meter having an optical means for measuring the relative position shift between a plurality of band detectors built in the radiation meter body and a function means for calibrating the inter-band resistoration with the use of the output of the optical means. CONSTITUTION:The title meter includes a movable mirror 186 capable of selectively inserting in light path of the optical system 121 for a camera part 71 and a calibration part 180 which includes an optical system 185 to form on CCDs 174/175, a projection image 183A of the stripe calibration pattern 183 for testing whether each CCD element in CCD174/175 are on the corresponding positions each other on the focus plane. Also, a deformatter 16 to control the insertion of the movable mirror 186 into the light path.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging radiometer, and more particularly to a multi-band imaging radiometer mounted on a moving body such as an artificial satellite or an aircraft for band-shaped imaging of a target area on the ground surface or the like.

[0002]

2. Description of the Related Art An imaging radiometer of this kind is used for remote sensing of a target area along the orbit of a moving body. For example, the National Aeronautics and Space Administration (NAS)
A multispectral scanner (MSS) and a thematic mapper (TM), which are typical imaging radiometers mounted on Landsat, which is one of the artificial satellites for remote sensing of A), are well known. Also, as recent ones, for example, the Proceedings of the Fourteenth International Symposium on Space Technology and Science (PROCEEDINGSOF) published in Tokyo in 1984.
THE FOURTEENTH INTERNATI
ONAL SYNPOSIUM ON SPACE A
ND SCIENCE, pages 1313 to 1319, "The Development of Multispectral Self-scanning Radiometer For MOS-1" (THE DEVELOPMENT)
OF MULTI-SPECTREL ELECTRO
NICSELF-SCANNING RADIOMET
ER FOR MOS-1) multi-spectral electronic self-scanning radiometer (MESSR), and the 34th Congress of the International Astonochical Federation held in Budapest in 1983 ( 34th CONGRESS OF THE INT
ERNATIONAL FEDERATION) IAF-83-109 "The SPOT-HRV.
Instruments: Anne Overview of Design and Puff Performance "(The SPOT-H
RVInstrument: AnOverview o
f Design and Performance)
HRV (High Resoluti described in
on Visible camera). The MESSR and HRV are linear array type CCDs in which a plurality of photoelectric elements are linearly arranged as photoelectric detection elements.
This is an imaging radiometer of this type using.

These imaging radiometers observe the intensity of visible light or infrared light radiated or reflected from the imaged target area on the surface of the earth, that is, the target area, that is, the radiance, and the brightness corresponding to the radiance. Generate an image composed of pixels. Also, in general, these imaging radiometers
A so-called multi-spectral band (hereinafter abbreviated as multi-band) type configuration is used in which the visible light or infrared light is divided into a plurality of wavelength bands, that is, spectral bands, and an image is generated in each band. The camera section of the imaging radiometer that performs the imaging includes an optical system that focuses radiation / reflection from the target area into a radiant flux corresponding to the radiance, and a photoelectric tube or a linear array CCD that converts the radiant flux into an electric signal. And a detector including a photoelectric element. The radiant flux is divided into the plurality of bands by a split optical system composed of a band separation mirror or prism arranged in the optical path, and each band is divided by a detector dedicated to that band arranged at the focal position of each band. It is converted into an electrical signal. Linear array CC
The MESSR using D as a detector has three bands of visible light,
It has a total of 4 spectral bands of 1 band of infrared light. Therefore, the number of divisions of the radiant flux is 4, and four detectors corresponding to the respective bands are provided. If the positional relationship between the detectors of these multiple bands or the optical paths of the optical systems corresponding to the detectors do not exactly match the design values, there will be a positional shift between the pixels of the received image of each band. Occurs. The registration between the pixels of this image is called registration. The registration between the multi-band images as described above is called inter-band registration.

In the mechanical scanning type imaging radiometer such as MSS or TM using a vibration or rotating mirror, the number of photoelectric elements of the detector may be several or at most several for each band. Band-to-band registration can be easily established. The above MSS has 6 photoelectric elements for each band, and the above TM has 16 photoelectric elements for each band (4 for one band), and the photoelectric element pitch corresponding to the pixel pitch is 100 μm. It is relatively large. Therefore, the alignment error of the photoelectric element allowed at the time of assembly of the detector reaches about 1/10 of the pixel pitch, which is considerably large. Further, fluctuations in band-to-band registration due to external factors such as impact at launch and temperature fluctuations are very small.

On the other hand, in a multi-band imaging radiometer including a linear array CCD as a radiation detector like the above MESSR and HRV, a plurality of CCs of CCD detectors corresponding to each band are required to establish inter-band registration.
The above alignment needs to be performed for each of the D elements.
More specifically, the linear array CCD which is the detector of the MESSR has a C for each of the four bands.
Since the number of CD elements is 2048, the element pitch is 14 μm, and the focal plane length is 28.67 mm, if the allowable error of band-to-band registration is within 0.1 pixel as in the case of the above MSS, the element positions of the bands are mutually different. The maximum permissible error in the lengthwise deviation is 1.4 μm. CCD currently under development
In an electronic scanning multi-band imaging radiometer with about 5000 elements, the element pitch is about 7 μm, so the maximum allowable error of the band-to-band registration is 0.7 μm.
m. It is very difficult to keep the error within this range at the current state of the art. That is, the above MESSR and H
RV is an essential advantage of electronic scanning, that is, the dwell time, which is the time to gaze at a target when the same resolution and the same scanning width are used, is large. Although it has the advantage of being simple, it involves the problem that the band-to-band registration is difficult.

Remote sensing by a multiband imaging radiometer not only processes images of a plurality of bands individually, but also performs feature extraction by comparing the features of the images of the observation target ground surface for each spectral band. Often, a multi-band image in which images of these plural bands are superimposed is used. On the other hand, the conventional imaging radiometer described above does not have the function of detecting an abnormality in the adjustment state of the band-to-band registration. Therefore, the adjustment and calibration of the band-to-band registration have to be performed at the time of manufacturing and mounting on the moving body. Further, after the moving body is launched, it is impossible to detect the deviation of the registration between the bands due to the deformation of the structure or the deformation of the detector mounting portion due to the impact or temperature change at the time of launch. .. For this reason, the band-to-band registration after the launch has been nothing but the so-called geometric correction based on the position of the specific target on the actual image in the image processing on the ground. This geometric correction method selects several specific targets on the image of a certain band, for example, several targets with a large output level difference on the ground such as the tip of a peninsula, and determines the pixel position and time of the output image. As a reference, the image processing parameter is corrected by measuring the displacement of the position of the specific target on the image of another band in pixel units. According to this method, it is impossible to cope with the increase in the number of pixels and the increase in the image processing amount accompanying the increase in resolution and the increase in scanning width. That is, as the resolution is increased and the scanning width is increased, the amount of information to be processed for the geometric correction is increased, and the downsizing of the image processing apparatus and the speeding up of the image processing are restricted. Further, there is a problem that the selection of the specific target is restricted by the weather condition of the target area, and the accuracy of the geometric correction is lowered. Referring to FIG. 7 showing a remote sensing system using a conventional imaging radiometer, a conventional imaging radiometer 11 mounted on an artificial satellite 10 is shown.
Scans the ground surface in a strip shape, for example, in the direction of arrow F with a scanning width of 100 km, and sets the data of the target area 30 to the ground surface resolution 50.
Collect in m. The collected data is the imaging radiometer 11
And is transmitted to the ground station 21 by the wireless data link transmitter. In addition, from the ground station 21, satellites according to a preset schedule
The position information on the orbit of 10 and the control information for setting the sensitivity of the imaging radiometer 11 by distinguishing the land area and the sea area of the target area 30 at the orbit position as a command through a wireless data link as an artificial satellite. Supply to 10. The artificial satellite 10 receives these position information and control information and uses them as control signals for the imaging radiometer 11. As described above, the artificial satellite 10 takes the sun-synchronous quasi-return orbit, and has an orbital altitude of 900 Km, an orbital inclination angle of 99 °, and an orbital period of 103 minutes, that is, a ground surface scanning speed of about 6.7 Km / S. The data transmission of the wireless data link is limited to the time when the artificial satellite 10 can be seen from the ground station 21, and is about 1 per revolution.
5 minutes. Referring to FIG. 8, the imaging radiometer 11 is
Camera unit 12 including optical system 121 and detection unit 122
A signal processing unit 13 for transmitting the data of the camera unit 12 to the ground station 21, a wireless data link transmitter 14 for transmitting the data to the ground station 21, and a data link for receiving a command from the ground station 21. The receiver 15 and the de-fou-matter 16 for separating the above command into a control command for the signal processing unit 13 and a command for the other artificial satellite 10 are provided. The detection unit 122 of the camera unit 12 is a linear array CCD 4 having 2000 CCD elements.
It is provided with a configuration in which the individual pieces are arranged corresponding to the four observation target bands 1 to 4 to give a ground surface resolution of 50 m, but here, for convenience of explanation, regarding the two CCD arrays corresponding to the two bands. Let me just explain.

Referring to FIG. 9 together, the detection unit 122 includes a beam splitter 12 including a spectroscopic element such as a prism for separating incident light into two spectral bands 1 and 2.
3 and the light receiving elements of bands 1 and 2, the number of elements is 2000, the element pitch is 14 μm, and the focal plane length is 28.7.
mm CCDs 124 and 125.

Referring again to FIG. 8, the signal processor 13
Are amplifiers 131A and 131B for amplifying the output signals of the CCDs 124 and 125 with a gain set by the gain control signal from the deformatter 16, and an A / D converter for converting the output signals of these amplifiers into 8-bit digital signals, respectively. 132A / 132B, and a formatter 133 for time-division-multiplexing the digitized data and a telemeter signal for monitoring the operating state of the artificial satellite 10.

Referring to FIG. 10, the ground station 21 shown in this figure has a console 211 for setting a control command including a sensitivity setting command, a transmission processor 212 for converting the control command into a signal for transmission, and transmission. Machine 213
A duplexer 214 that superimposes and separates the transmission and reception, an antenna 215 that tracks the artificial satellite 10, a receiver 216, and a high-density recording device (HDDT) 220 that temporarily records the data received by the receiver 216. ,
HDDT with reference to data from database 219
A data processing device 217 that processes the received data from 220 and outputs the image data, and an image output device 218 that images the image data and outputs the image data. The database 219 contains geometric correction data for band-to-band registration processing.

The operation of this conventional example will be described with reference to FIGS. 7 to 10. First, in the ground station 21, the console 21
1, according to the imaging schedule of the target area 30,
The position information of the artificial satellite 10 on the orbit and the information indicating the land / sea area or the plain / mountain area of the target area 30 at the orbit position are generated, and the imaging radiometer 11 is generated based on the information.
The sensitivity of is set to 0 dB. In the transmission processor 212, the sensitivity setting command CS is multiplexed with other control commands of the artificial satellite 10 and is transmitted as a control command to the transmitter 2
13 is supplied. The transmitter 213 transmits the control command to the artificial satellite 10 via the duplexer 214 and the antenna 215. The data link receiver 15 of the artificial satellite 10 receives this and inputs it as a control signal CSA to the de-foumatter 16. Def Omatter 16
Extracts a control command for the signal processing unit 13, decodes the sensitivity setting command CS among them, and supplies it to the amplifiers 131A / 131B as a sensitivity control signal SS.
The amplifiers 131A / 131B are set to the gain H corresponding to the sensitivity 0 dB by the sensitivity signal SS designating the sensitivity 0 dB as described above. Next, the CCD 124/12 of the camera unit 12
The analog data A1 / A2 from 5 is the signal processing unit 13
131A / 131 with gain set to 0 dB sensitivity
Each is amplified in B. The output of these amplifiers is A / D
The conversion units 132A / 132B respectively perform A / D conversion to obtain 8-bit digital data D1 / D2. Next, these digital data D1 / D2 are converted from parallel to serial in the formatter 133, and further,
It is formatted together with the above housekeeping data and the like. The output of the formatter 133 is transmitted to the ground station 21 by the data link transmitter 14.

In the ground station 21, the received data supplied to the data receiver 216 via the antenna 215 and the duplexer 214 is recorded in the HDDT 220 and further supplied to the data processing device 217 for processing. The data processing device 217 refers to the data in the database 219, corrects the scanning distortion of the received data and the sensitivity variation of the detector, and generates image data. These processes apply to the individual observation bands 1 and 2, namely CCDs 124 and 12
5 for each output data. The image thus obtained is a single band image of bands 1 and 2.
In the case of generating a multi-band image in which the single-band images of each of these bands 1 and 2 are generated, the CCD 124/125 stored in the database 219 is further added.
Geometric correction processing for band-to-band registration is executed using the alignment data of. The single band data output data of each of the bands 1 and 2 from the data processing device 217 is imaged as a single band image of each of the bands 1 and 2 by an image output device 218 by a high density film recorder. The brightness of the pixels of this image is proportional to the level of the image data, and the image becomes monochrome. Any color for identifying the imaging, usually in each band data of bands 1 and 2,
For example, red is assigned to band 1 and green is assigned to band 2 in advance. As a result, the output image becomes a multicolor image composed of red and green. A multi-color image obtained by this method is called a pseudo color image. It should be noted that the transmission of the above-mentioned command and the reception of the imaging data can be performed within the transmission possible time of about 15 minutes of the wireless data link.

Next, referring to FIGS. 11A and 11B,
A method of adjusting and calibrating band-to-band registration on the ground will be described. Referring to FIG. 11 (A), a collimator 80 including a slit 81 attached to a focus and a light source 82 is attached to an optical axis (Z
Arrange so that the (axis) matches. Further, the longitudinal direction (X axis) of the slit 81 is the CCD 124/125 of the radiometer 11.
It is set so as to be perpendicular to the arrangement direction (Y axis) of the photoelectric elements, that is, the width direction of the slit 81 is the Y axis. The collimator 80 collimates parallel rays L in the shape of the slit 81 to enter the radiometer 11, moves the slit 81 along the Y axis, and the CCDs 124 /,
The output of each of 125 photoelectric devices to be measured, for example, the device outputs of the center and both ends (5th, 1000th and 1995th) is individually measured. The above movement is performed by the CCD 124
It is performed in the moving step corresponding to the element pitch of the photoelectric element of / 125. The above measurement results, CCD124 / 12
By comparing the positions of the slits 81 at which the element outputs of No. 5 have the highest level, the deviation in the element pitch unit can be measured. Referring to FIG. 11B, in the measurement result performed on the 1995th element, the CCD 1
It is shown that the deviation between the elements of 24/125 is two element pitches. Therefore, CCD124 /
125 is adjusted so that the root mean square value of each of the above-mentioned deviations measured for the elements at the center and both end portions is adjusted to be the minimum, and incorporated in the detection unit 122. The final deviation data obtained as a result of this adjustment is the alignment data of the CCD 124/125.

The focal length of the collimator 80 is set to about 10 times the focal length of the radiometer 11 to be tested. Therefore, the moving step is about 10 times the element pitch.
Doubled. The focal length of the radiometer 11 of this example is about 250 mm
Then, the focal length of the collimator 80 is 2.5 m, and the element pitch is 14 μm as described above, so the moving step is 140 μm.

CC of the radiometer 11 thus obtained
The alignment data of D124 / 125 is the ground station 21.
It is stored in the database 219 for geometric correction of image processing in the data processing device 217. The orbital position data and attitude data of the artificial satellite 10 are compared with the read output of the database 219, and the CCD 124
Geometric correction is performed for each band 1/2 corresponding to the output of / 125. Thereby, band-to-band registration calibration on the output image is performed.

[0015]

Since the conventional imaging radiometer described above does not have a function of detecting an abnormality in the adjustment state of the band-to-band registration, the impact at the time of launching after the launch of the moving body is not achieved. Since it is impossible to detect the deviation of the band-to-band registration due to the deformation of the structure or the deformation of the detector mounting part due to temperature change, etc., the band-to-band registration after launch will be performed on the ground. In processing, there is nothing but geometric correction based on the position of a specific target on the actual image, but the above-mentioned geometric correction due to the increase in the number of pixels and the increase in the amount of image processing due to the increase in resolution and the increase in scanning width. However, there is a drawback in that the information to be processed is increased, and downsizing and speeding up of the image processing apparatus are restricted. Further, there is a problem that the selection of the specific target is restricted by the weather condition of the target area, and the accuracy of the geometric correction is lowered.

Therefore, an object of the present invention is to provide an optical means for measuring the deviation of the relative positional relationship of the detectors of a plurality of bands incorporated in the radiometer main body, and the inter-band registration by the output of the means. An imaging radiometer having means for performing a calibration function.

Another object of the present invention is to eliminate the need for band-to-band registration processing by geometric correction in terrestrial image processing, and therefore to speed up image processing and simplify the image processing apparatus. It is to provide a radiometer.

Still another object of the present invention is to provide an imaging radiometer that performs highly accurate band-to-band registration by the band-to-band registration calibration function without being affected by the weather in the target area.

[0019]

An imaging radiometer of the present invention is mounted on a moving body that travels above an area to be imaged on the surface of the earth along a trajectory having a predetermined positional relationship with the area. A unit imaging area defined by a predetermined width and a distance in the navigation direction of the moving body is included in the visual field, and visible light / infrared rays from the unit imaging area are divided into first and second spectral band rays. And a first optical system for forming an image on the first and second focal planes respectively, and a distribution of luminance in the focal plane of the rays of the first and second spectral bands respectively arranged on the focal plane. The unit image pickup device includes first and second photoelectric conversion means each of which is composed of a plurality of photoelectric conversion elements arranged in an array so that they can be detected, and the unit imaging enters the field of view as the moving body navigates. In an imaging radiometer for sequentially capturing optical images in the first and second spectral bands of a region, the first and second movable mirrors including a movable mirror that can be selectively inserted in an optical path of the first optical system. The photoelectric image of the striped calibration pattern for testing whether or not the photoelectric conversion elements of each of the photoelectric conversion means are at positions corresponding to each other on the first and second focal planes. It comprises calibration pattern forming means including a second optical system formed in the second photoelectric conversion element, and optical path switching means for controlling the insertion of the movable mirror into the optical path.

[0020]

EXAMPLE An example of the present invention will now be described with reference to FIGS. 1 to 4, 5A, and 5B. Referring to FIG. 1 which is a block diagram showing an embodiment of the present invention, an imaging radiometer 17 of the present embodiment has an optical system 121 similar to that of the imaging radiometer 11 described above and a detection with high resolution described later. The camera unit 71 including the unit 172 and the calibration unit 180 for the band-to-band registration test according to the present invention, the signal processing unit 13 including the same components as the conventional one, and the ground station 21 described above.
To the signal processing unit 13 and the camera unit 71. The data link transmitter 14 for transmitting the imaging data to the camera, the data link receiver 15 for receiving the command from the ground station 21, and the control command from the data link receiver 15 for the signal processing unit 13 and the camera unit 71. And a default formatter 16 for separating control commands other than the above.

The band to be observed and the scanning width of the imaging radiometer 17 are 4 bands and 100 km as in the conventional example, and the resolution is 20 m, which is much higher than that in the conventional example. The detection unit 172 of the camera unit 71 has a pitch of 7 μm so as to give sufficient ground resolution to each of the observation target bands 1 to 4.
4 linear array CCDs consisting of 5000 CCD elements. Here, for convenience of description, only two of these four will be described.

Referring also to FIG. 2, the detector 172 includes a beam splitter 173 similar to the detector 122 described above.
CCD 174/175. The calibration unit 180 includes lamps 181/187, which are the light sources for calibration, and lamps 181/18.
Diffusion plate 18 for uniformizing the irradiation light from 7
2/188, a pattern 183 for calibrating the element array direction, and a pattern 18 for calibration in a direction perpendicular to the element array direction
9, half mirror 184, and calibration optical system 185
In addition, during observation, the incident light from the optical system 121 of the radiometer main body is retracted outside the optical path so as to enter the detection unit 172, and during calibration, the incident light from the optical system 121 is blocked and the calibration optical system 185 is used. Incident light from the detector 17
2 and a movable mirror 186 that makes the light incident on the beam 2.

During normal observation, the ground station 21
In addition to the control command including the sensitivity setting command CS for the artificial satellite 10 by the console 211, a command CU for instructing normal observation is set, and the command CU is set to the transmission processor 212, the transmitter 213, and the duplexer 21.
3, and transmits to the artificial satellite 10 via the antenna 215. This command CU is received by the data link receiver 15 and separated by the de-fou-matter 16. Based on this, the movable mirror 186 of the calibration unit 180 is retracted to the observation position, that is, outside the main optical path, and the incident light from the optical system 121 is The light enters the detection unit 173, and thereafter, operates similarly to the above-described conventional example.

Next, when calibrating the band-to-band registration, the ground station 21 sets a command CY instructing the calibration execution in the element array direction (Y) from the console 211 and transmits it to the artificial satellite 10 (step S1). ). Calibration unit 1 based on command CY from differential formatter 16
The movable mirror 186 of 80 enters the calibration position, that is, the main optical path, and the incident light from the optical system 185 enters the detector 173 (step S2). Next, the lamp 181 is turned on, the illuminance of the entire irradiation surface is made uniform by the diffusion plate 182, and the pattern 183 is irradiated, and the image of the pattern 183 is formed by the optical system 18.
5, the image is projected onto the detection unit 172 and a projected image 183A is generated on the light receiving surface of the CCD 174/175 (step S).
3). Next, the CCD 174 /
The output signal A1 / A2 of 175 is amplified and A / D converted by the signal processing unit 13, and transmitted as calibration data to the ground station 21 via the data link transmitter 14 (step S
4). Next, in the ground station 21, the projected image 183A is transmitted via the antenna 215, the duplexer 214, and the receiver 216.
Data is recorded in the HDDT 220. This recording corresponds to one scene of the processed image, that is, about 70 km,
It is performed for about 10.5 seconds from the surface scanning speed of 6.7 Km / S of the artificial satellite 10 (step S5). Next, the ground station 21 sets a command CX for instructing the calibration execution in the direction (X) perpendicular to the element array by the console 211 and transmits it to the artificial satellite 10 (step S6). Based on the command CX from the differential formatter 16, the lamp 181 is turned off, the lamp 187 is turned on, and the pattern 189 is irradiated through the diffusion plate 188.
The projected image 1 on the light receiving surface of CCD 174/175 by 85
89A is generated (step S7). Next, the output of the CCD 174/175 based on this projected image 189A is used as calibration data via the data link transmitter 14 and the ground station 2
1 (step S8). Next, the ground station 21 similarly records the data of the projected image 189A in the HDDT 220 for about 10.5 seconds (step S9). When the acquisition of the series of calibration data DY / DX is completed, the ground station 21 sets the command CU again and transmits it to the artificial satellite 10 (step S10). In the imaging radiometer 17,
Movable mirror 186 of calibration unit 180 based on command CU
Is set as the observation position (step S11), and normal observation is executed (step S12).

Referring to FIG. 5B showing the procedure for obtaining the pixel shift R between the bands in the element array direction (Y) in step 13 in the image processing, referring to FIG. 5B, the calibration data recorded in the HDDT are stored in the CCDs 174/175, respectively. The image processing is performed by the data processing device 217 for each of the output data. First, a pixel shift R between bands in the element array direction is calculated by a procedure described later in detail (step S1).
3). Next, the pixel shift T between the bands in the direction perpendicular to the element array direction is calculated (step S14).

The band-to-band registration calibration of the present invention is based on an optical vernier scale determined by the element pitch of the CCD and the pitch of the grid pattern of the projected image. The details of this optical vernier scale will be further described.

Referring to FIGS. 3 and 4 showing an example of performing band-to-band registration calibration of the 4990th to 5000th light receiving elements of the CCD 174 and CCD 175, CCD174 / 175 of the detector 172 is shown.
183 from the calibration unit 180 on the light receiving surface of the
The projected image 183A is a grid-like pattern that is perpendicular to the element arrangement direction of the CCD 174/175 and that has band-shaped light portions and shadow portions of the same width that are slightly different from the element pitch. The output level of each element of these CCDs 174/175 is determined by the ratio of the area of the above-mentioned light portion on the light receiving surface to the area of the mask portion due to the shadow portion, and also the total of the above-mentioned light portion and the shadow portion of the projected image 183A. The output level periodically fluctuates due to the grating pitch P, which is the width of the element, the element pitch S of the CCDs 174/175, and the positional deviation between the CCDs 174/175 in the element arrangement direction.

The period L of the output level fluctuation determined by the grating pitch P is expressed by the following equation.

L = P · n (n is an integer) ……………………………………………… (1) Further, the period L is related to the element pitch S by the following equation. ..

L = S · m (m is an integer) ……………………………………………… (2) From equations (1) and (2), n ・ P / m・ S = 1 …………………………………………………………………………………………………………………………………………………… (3) is L. For example, element pitch S =
If 7 μm and the grating pitch P = 12.5 μm, then (3)
From the equation, n = 4 (m = 7), and therefore the period L
= 49 μm. That is, the pitch is 7 element pitches.

Next, after the output of the CCD is subjected to sensitivity correction and dark area output correction for each element, the theoretical value of the element number versus the output level is obtained for each of the odd-numbered and even-numbered elements. The theoretical value is a straight line that monotonically increases or decreases according to the element number. In FIG. 4, a solid line a and a dotted line b indicate examples of the straight lines corresponding to even and odd numbers, respectively.

As is well known, the vernier scale is an auxiliary scale for further reading the scale by subdivision, and has a scale obtained by equally dividing the length of the u-1 or u + 1 scale of the main scale by u. The length 1 of the vernier scale is expressed by the following equation, where s is the interval between the main scales and 1 is the interval between the vernier scales.

L = u · p = (ru ± 1) s where r is a small integer and is generally 1 or 2.

The relationship between the main pitch and the sub-scale, which is defined by the grating pitch P and the element pitch S, can be considered to be a sub-scale consisting of the element as the main scale and the above-mentioned light and shadow portions of the grating. That is, the scale p of the above-mentioned vernier scale is 1/2 of the grating pitch P, that is, P / 2, the scale s of the main scale is the element pitch S, and u is 2n.
And the cycle L of the output fluctuation corresponds to the length 1 of the vernier scale. However, since the shaded portions do not contribute to the photoelectric conversion output of the element, every other scale in the main scale / subscale relation is effectively effective.

Next, two CCDs 1 having the same element pitch S
A case where 74/175 is displaced from each other by R in the element arrangement direction will be described. In FIG. 4, CCD 174 /
An example in which the output levels of the 4990th to 5000th elements of the CCD 175 are plotted is shown in FIG.
The solid line M and the dotted line N in FIG. As described above, the output is an 8-bit digital signal and its level is in the range of 0 to 255 in which a binary number is converted into a decimal number. Letting ΔL be the deviation of the solid line M and the dotted line N in the element arrangement direction at an arbitrary level 255, this deviation R is expressed by the following formula (4) from the theory of vernier scale in terms of element pitch.

R = (ΔL / L) · (P / 2S) ………………………………………… (4) If the deviation R is 0, ΔL = 0, that is, the solid line M and the dotted line N are overlapped and shown as one line. Further, ΔL takes two values depending on whether the element number is smaller or larger. In this example, ΔL corresponds to a deviation of 3 element pitches from the larger element number or 4 element pitches from the smaller element number, so the deviation R is 0.375 from the former and 0.5 from the latter. It will be either. On the other hand, as mentioned above,
The output level of each element is determined by the ratio of the area of the above-mentioned light portion on the light-receiving surface to the area of the mask portion due to the shadow portion. Therefore, if the output levels of elements of the same number are compared, it is expressed as the ratio. The difference is approximately proportional to the deviation R.
Now, to determine which one is 4991
Focusing on the output of each of the second elements, assuming that the output level 255 of the CCD 175 is 1, the output level of the CCD 174 is 191 which is about 3/4. Also, 49 of CCD175
The output level of the 92nd element is 31 or about 0.12
Therefore, the shift R is between the 0.25 element pitch and the 0.38 element pitch. Therefore, the deviation R is 0.3
It can be judged as 75. This shift R becomes a calibration value of the band-to-band registration.

Referring to FIG. 6 showing an example of band-to-band registration calibration in the direction perpendicular to the element array direction, the projected image 189A of the calibration pattern 189 is the CCD 174.
This is a slit-shaped pattern having an angle of θ with respect to the element arrangement direction of / 175. The width of the slit is the same as the element pitch S, that is, 7 μm, and neither the upper edge nor the lower edge of the slit masks the element, for example, 49
The output level of the 97th element is set to 500 as the reference value VC.
Assuming that the output level of the 0th element is V1 / V2, the deviation T between the CCDs 174/175 in the direction perpendicular to the element arrangement direction is expressed by the following equation.

T = (V1−V2) / VC …………………………………………………… (5) The unit of the deviation T is the vertical size of the device. Also, C
The inclinations θ1 and θ2 of the CD174 / 175 with respect to the respective element arrangement directions are represented by the following equations.

Θ1 = {1- (V1 / VC)} S / 4S …………………………………… (6) θ2 = {1- (V2 / VC)} S / 4S …… ……………………………… (7) If VC = 256, V1 = 241, V2 = 231,
The deviation T is 0.039 element pitch, and the inclinations θ1 and θ2 are 14.6 and 24.6 (mrad), respectively.
That is, 50 minutes and 84 minutes.

Referring to FIG. 5B, first, step S3
From the calibration data DY1 / DY2 of the CCDs 174/175 collected in steps S5 to S5, pixels are sorted into odd-numbered and even-numbered pixels, respectively, and arranged as data for imaging. That is, the odd numbers are arranged so as to be 1,3,5 ... 4997,4999th, and the even numbers are arranged so as to be 2,4,6 ... 4998,5000th (step S131). The odd-numbered ones of these data strings are OY11 and OY21, and the even-numbered ones are EY11 and EY21. Next, the level of the data of each pixel of OY21 is inverted to generate the inverted OY21 (step S132). Next, OY11 and inverted OY21
The data of the inversion OY21 is shifted in the pixel array direction so that the levels of all the pixels are minimized when the data of the corresponding pixels are added. In the present embodiment, the above condition is satisfied when the inversion OY21 is shifted to the left by 3 pixel pitch for the 4990th to 5000th data comrades.
This shift amount is the deviation ΔLO between the odd-numbered pixels (steps S133 to S136). Similarly, the shift ΔLE between the even-numbered pixels is obtained (step S137).
Next, the average value of these ΔLO and ΔLE, that is, the shift ΔL between pixels is obtained (step S138). When the above-mentioned added data is imaged for both the odd-numbered and even-numbered data strings, a low-level, almost uniform image is obtained on the entire screen. In this way, the portion of the difference having a value different from ΔL becomes extremely bright and can be easily discriminated.
On the other hand, the period L is a constant set by the grating pitch P of the projected image 183A determined by the grating pitch of the calibration pattern 183 and the magnification of the optical system 185, and the element pitch S of the CCD 174/175, so that the inter-band resist The calibration value R of the ratio can be easily obtained by the equation (4) (step S139).

Next, the procedure for obtaining the pixel shift T between the bands in the direction (X) perpendicular to the element array direction in step 14 is as follows. First, the CCD 1 collected in steps S6 to S8.
The respective calibration data DX1 / DX2 of 74/175 are imaged. The element number of the measurement target, in this embodiment, the pixel of the strongest level near the 5000th, that is, the 4997th pixel is extracted and this output level is used as the reference value VC for measurement. The level V1 / V2 of the 5000th pixel of the calibration data DX1 / DX2 is measured, and the shift T in the direction perpendicular to the element array direction is obtained by the equation (5). Since the measurement of these levels is well known in image processing, description thereof will be omitted. The calibration values R and T of the band-to-band registration correct the geometric correction parameters of the image processing stored in the database 219 (step 15).

[0042]

As described above, the imaging radiometer of the present invention includes the movable mirror that can be selectively inserted in the optical path of the first optical system, and each of the first and second photoelectric conversion means described above. An optical image of a striped calibration pattern is formed on the first and second photoelectric conversion elements to test whether or not the photoelectric conversion elements are at positions corresponding to each other on the first and second focal planes. By providing the calibration pattern forming means including the second optical system and the optical path switching means for controlling the insertion of the movable mirror into the optical path, the band-to-band registration is measured on the moving body, and the data thereof is measured. Can be used for image processing on the ground side,
There is no need for processing for band-to-band registration, and therefore, there is an effect that image processing can be speeded up and image processing can be simplified.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an imaging radiometer of the present invention.

FIG. 2 is a diagram schematically showing a configuration of an optical system included in an example of the present invention.

FIG. 3 is a diagram showing a state in which a registration calibration light pattern is projected on a light receiving element of each band.

FIG. 4 is a diagram showing the output level of the light receiving element of each band in the state of FIG.

FIG. 5 is a flowchart for calibration of band-to-band registration and a flowchart for calculation of band-to-band pixel shift in the above embodiment.

FIG. 6 is a diagram showing a state in which a slit-shaped light pattern having an angle of θ with respect to a pixel array is projected on a light receiving element.

FIG. 7 is a diagram of an example of a remote sensing system using a conventional imaging radiometer.

FIG. 8 is a block diagram of an example of a conventional imaging radiometer.

9 is a configuration diagram of an optical system of the imaging radiometer of FIG.

10 is a block diagram of an example of a configuration of a ground station of the system of FIG.

FIG. 11 is an explanatory diagram of an adjustment method and a test method of band-to-band registration of a conventional imaging radiometer and a graph of an example of test results.

[Explanation of symbols]

 10 Artificial Satellite 11,17 Imaging Radiometer 12,71 Camera Section 13 Signal Processing Section 14 Data Link Transmitter 15 Data Link Receiver 16 Defomatta 21 Ground Station 30 Target Area 80 Collimator 81 Slit 82 Light Source 121,176,185 Optical System 122,172 detection part 123,173 beam splitter 124,125,174,175 CCD 131A, 131B amplifier 132A, 132B A / D converter 133 formatter 180 calibration part 181,187 lamp 182,188 diffuser plate 183,189 pattern 183A, 183B Projected image 184 Half mirror 186 Movable mirror 211 Console 212 Transmit processor 213 Transmitter 214 Duplexer 215 Antenna 216 Receiver 217 Data processing device 218 image Image output device 219 database 220 HDDT

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location G01J 5/48 E 8909-2G F 8909-2G

Claims (9)

[Claims] 1. A predetermined width of the area and a distance in the navigation direction of the moving body, which is mounted on a moving body that travels above an imaging target area on the ground surface along an orbit having a predetermined positional relationship with the area. And a visible light ray / infrared ray from the unit image pickup region is divided into light beams of first and second spectral bands and is respectively coupled to the first and second focal planes. A first optical system for forming an image, and a plurality of first optical systems respectively arranged in the focal plane and arranged in an array so as to respectively detect the luminance distributions of the rays of the first and second spectral bands in the focal plane. First and second photoelectric conversion means comprising photoelectric conversion elements, and the first and second spectral bars of the unit imaging region entering the field of view as the moving body navigates. In an imaging radiometer for sequentially capturing an optical image in a band, the photoelectric conversion of each of the first and second photoelectric conversion means includes a movable mirror that can be selectively inserted in an optical path of the first optical system. Forming an optical image of a striped calibration pattern on the first and second photoelectric conversion elements for testing whether or not the elements are at positions corresponding to each other on the first and second focal planes; An imaging radiometer, comprising: a calibration pattern forming unit including the second optical system; and an optical path switching unit that controls insertion of the movable mirror into the optical path. 2. The optical image of the calibration pattern is the first image.
A first photoelectric conversion element having a width substantially equal to that of the light-receiving surface of the second photoelectric conversion means and having a length substantially equal to that of the photoelectric conversion element, and the pitch of the striped pattern is slightly different from the arrangement pitch of the photoelectric conversion elements. 2. The imaging radiometer according to claim 1, wherein the image is a calibration optical image pattern. 3. The optical image of the calibration pattern is a striped second calibration optical image pattern extending at a predetermined angle with respect to the arrangement direction of the photoelectric conversion elements. Item 1. The imaging radiometer according to Item 1. 4. The optical path switching means retracts the movable mirror from the optical path of the first optical system to the outside of the optical path when the unit imaging area is imaged, and causes the movable mirror to move to the optical path when the calibration pattern is generated. The imaging radiometer according to claim 1, further comprising means for inserting. 5. A unit for a predetermined width of the area and a navigation direction of the moving body, which is mounted on a moving body that travels above an imaging target area on the ground surface along an orbit having a predetermined positional relationship with the area. A unit imaging area that is elongated in the width direction defined by the distance is included in the field of view, and light rays such as visible rays from the unit imaging area are divided into first and second spectral band rays. An optical system for forming an elongated first and second optical image on a second focal plane, and an optical system arranged on the focal plane for converting the first and second elongated optical images into electric signals, respectively. A first photoelectric conversion means and a second photoelectric conversion means, each of which is composed of a plurality of photoelectric conversion elements linearly arranged at a predetermined element pitch along the optical image, unit An imaging radiometer that sequentially captures the optical images in the first and second spectral bands of the imaging region as a chain of the optical images corresponding to the unit imaging region, wherein the first and second photoelectric conversion means are provided. An optical image of a repeating dark color stripe pattern having a pattern pitch and a width that have a predetermined relationship with the element pitch so that a deviation from corresponding positions on the first and second focal planes can be detected. A means for selectively forming at the position of the second photoelectric conversion means, and means for calculating the deviation in response to the outputs of the first and second photoelectric conversion means at the time of forming the stripe pattern optical image. An imaging radiometer characterized by the above. 6. In order to improve the accuracy of calculation of the deviation,
The imaging radiometer according to claim 5, wherein the element pitch forming at least a part of the photoelectric conversion means is in a major / subscale relationship with the pattern pitch. 7. The shift calculating means compares the output of every other one of the plurality of photoelectric conversion elements of the first photoelectric conversion means with the output of the corresponding photoelectric conversion element of the second photoelectric detection means. The imaging radiometer according to claim 5, further comprising: 8. A slit orientation having a predetermined relationship with the element orientation so that deviations from corresponding element orientations in the first and second focal planes of the first and second photoelectric conversion means can be detected. 6. The imaging radiometer according to claim 5, further comprising means for selectively forming an optical image of a slit pattern having a width and a width at the positions of the first and second photoelectric conversion means. 9. The imaging radiometer according to claim 5, 7, or 8, wherein said stripe pattern optical image forming means, deviation calculating means, and slit pattern optical image forming means are driven by a command signal from a ground station.