JPH02918B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an imaging method for obtaining three-dimensional information such as the ups and downs of the earth's surface from an artificial satellite or the like orbiting the earth.

In so-called remote sensing, which observes conditions on the earth's surface from artificial satellites, it is desired to obtain not only two-dimensional information but also three-dimensional information on the earth's surface, especially in the field of resource exploration. It is generally well known that in order to obtain three-dimensional information about a target object, it is necessary to synthesize observation images from two distant points. When trying to obtain a stereoscopic image of the earth's surface from an artificial satellite, it is usually difficult to obtain a stereoscopic image at the same time using a single satellite because the distance to the earth's surface is large. For this reason, it has been proposed to obtain stereoscopic images using vertical movement of satellites.

The first example is an example of a three-dimensional imaging method that has been proposed so far.
As shown in the figure. In FIG. 1, reference numeral 1 indicates an artificial satellite, and reference numeral 2 indicates an imaging device for performing stereoscopic imaging. The imaging device 2 includes two optical systems 3 and 4 for performing stereoscopic imaging.
, and photoelectric conversion elements 5 and 6 are arranged at the focal plane of each optical system.

In FIG. 1, an artificial satellite 1 moves at a speed v relative to the earth's surface. At position A, the forward imaging optical system 3 images the ground surface P and forms the image on the photoelectric conversion element 5. Similarly, the rear imaging optical system 4 is connected to the ground surface Q.
is imaged and focused on the photoelectric conversion element 6. Satellite 1
continues to take images while traveling, and at the time when it advances to position B, the rear imaging optical system 4 takes an image of the ground surface P. Using this image data and the image data of the ground surface P captured by the optical system 3 from the above-mentioned position A, it is possible to obtain three-dimensional information of the ground surface P using the same principle as when stereoscopic vision is normally performed with human eyes. I can do it.

A drawback of this conventional method is that it requires at least two optical systems to obtain stereoscopic information. Compared to the case where plane information is obtained by imaging only the point directly below the satellite, the increase in the number of optical systems causes a large increase in weight and size, which is a disadvantage for use on a satellite with large restrictions. Also, 2
Since it is necessary to precisely set the alignment between the individual optical systems, a complicated setting method is also required for mounting the optical systems.

Further, since this type of imaging device is normally required to perform stereoscopic viewing and to image a point directly below, in this case, three optical systems are required as shown in FIG. As is clear from this figure, the aforementioned weight, size and alignment conditions are even more disadvantageous in this case.

As a method using a small number of optical systems, stereoscopic viewing using a configuration as shown in FIG. 3 is also possible. This has one optical system, and a movable mirror 7 is placed in front of it as shown in the figure.
is provided, and by switching this angle, stereoscopic viewing is performed. This method uses movable mirror 7
Although there is an advantage that the imaging location can be selected by setting the angle of the
This method has disadvantages such as not being able to image certain areas, resulting in discontinuous stereoscopic images.

An object of the present invention is to provide an imaging method that eliminates the drawbacks of these conventional methods and can perform stereoscopic imaging and multi-band observation of a direct point with a simple configuration.

The present invention will be explained in detail below with reference to the drawings.

FIG. 4 is an explanatory diagram showing the principle of the three-dimensional imaging method according to the present invention, and FIG. 5 is a partially enlarged view of a portion connecting the imaging plane and the light receiving element in the method shown in FIG. 4. In the figure, reference numeral 27 indicates a wide-angle optical system for imaging the ground surface, and reference numeral 8 indicates an imaging plane of this optical system. Reference numerals 9 to 11 denote optical fiber bundles for directly transmitting images, and as shown in the figure, each of them has aperture ends arranged one-dimensionally on the imaging plane of the optical system. The opening ends are further arranged one-dimensionally on a line that is substantially perpendicular to the direction in which the imaging device travels, and are arranged substantially parallel to each other.

The other open ends of the optical fiber bundles 9-11 are connected to light-receiving elements 12-14, as illustrated in the embodiment of FIG. Further, each of the optical fiber bundles 9 to 11 is composed of a collection of independent thin optical fibers as an optical signal transmission system. Therefore, the optical signal incident on the entrance aperture end of each optical fiber is transmitted to each pixel that performs photoelectric conversion of the light receiving element without leaking to others. Further, by arranging the output aperture ends of the optical fiber bundles 9 to 11 and the photoelectric conversion parts of the light receiving elements 12 to 14 very close to each other or in close contact with each other, leakage to surrounding pixels can be prevented. As a result, the image of the ground surface formed at the aperture end is faithfully transmitted to the light receiving element.

A photoelectric conversion element such as a multi-element CCD (charge-coupled device) can be used as the light receiving element, and the optical signal supplied to the input end of the fiber bundle is supplied to the light receiving element such as the CCD, similar to a high-speed facsimile etc. It is output as a time series signal by electronic scanning.

Although the dimensions of the photoelectric conversion parts of the light receiving elements 12 to 14 are very small, the package that accommodates them is large as shown in Figure 5, and there are also lead-out electrodes on both sides.
In addition, an area of a printed circuit section for supplying signals thereto is required. Therefore, the light receiving elements 12 to 14
Placing the optical fiber directly into the image plane presents considerable difficulties, necessitating the use of a fiber optic bundle as in the present invention. In particular, with the recent demand for higher resolution, it has become necessary to have several times the number of pixels in a single one-dimensional light-receiving element within a scanning line. In this case, for example, as shown in FIG.
By branching one output end and connecting it to each light receiving element, it is possible to take advantage of the features of the system according to the present invention and perform stereoscopic imaging.

Furthermore, by using an optical fiber bundle, as shown in FIGS. 7a and 7b, it is possible to obtain effects that could not be achieved with a system in which the light-receiving element is placed directly on the imaging plane. That is, in FIG. 7a, the problem of field curvature occurring in the optical system can be eliminated by curving the input end of the fiber bundle by polishing or the like. Furthermore, as shown in FIG. 7B, by arranging the fiber bundles in accordance with the distortion aberration caused by the optical system, it is possible to eliminate the influence of the distortion aberration.

As shown in FIG. 4, the open end of the optical fiber bundle 9 is arranged so as to image the ground surface W (m) ahead of the point directly below. The open ends of the fiber bundles 10 and 11 are similarly arranged so as to image the point immediately below and the ground surface behind W(m), respectively.

As shown in the figure, images of the earth's surface P, O, and Q are formed at a position A by an optical system 27 having a large allowable angle of incidence. An image is formed at each end, guided by an optical fiber bundle to a light receiving element, and converted into an electrical signal. The imaging device continues imaging while moving at a speed v, and an image of the ground surface P is formed on the open end of the optical fiber bundle 11 at position B, and an image of the ground surface P is focused on the open end of the optical fiber bundle 9 at the aforementioned position A. Together with the imaged information on the ground surface P, three-dimensional information on the ground surface P can be obtained.

Light receiving elements 12 to 14 connected to the optical fiber bundle
The output signal is sent out via the signal processing circuit 15, the transmitter 16, and the antenna 17 shown in FIG.

FIG. 8 shows an example of a system diagram of a ground station device when the system according to the present invention is used. In the figure, 1
8 is a receiving antenna, 19 is a receiving demodulator, and 20 is a distribution circuit. Output signals 21, 2 of the distribution circuit 20
2 and 23 correspond to output signals 12, 13, and 14 on the transmitting side, respectively.

As shown in Figure 4, if the distances between the imaging position directly below the satellite and the front and rear imaging positions are each W (m), the time it takes for the satellite to move from position A to position B is 2τ = 2W/v (sec ). That is, after an image of the ground surface P is formed on the open end of the optical fiber bundle 9, an image of the same ground surface is formed on the open end of the optical fiber bundle 11 2τ seconds later. Therefore, as shown in FIG. 8, if a relative time delay of 2τ (sec) is given to the demodulated output 21 corresponding to the light receiving element 12, the output of the delay circuit 24 becomes the demodulated output 21 corresponding to the light receiving element 14. The output 23 is a signal obtained by imaging the same ground surface from different angles, and the image processing recording unit 25 can obtain stereoscopic image information.

Similarly, by giving a time delay of τ (sec) to the signal output 22 that captures the image of the direct point,
Information about the same ground surface can be input to the image processing recording section.

The delay circuit shown in FIG. 8 can also be configured with a digital memory circuit, etc. Also, in the transmitting section of FIG. According to
It is also possible to eliminate the delay circuit in the receiving section.

Furthermore, in the embodiments described above, the light-receiving element includes a one-dimensional pixel array, for example, a one-dimensional pixel array.
Although an example using a CCD has been described, the method according to the present invention uses an optical fiber bundle, so
Two-dimensional pixel arrangement in a plane as shown in the figure
It is also clear that CCDs can be used. In this case, as shown in the figure, the arrangement of the aperture ends on the imaging plane side of the optical fiber bundle is the same as in Figures 5 and 6, but the output end on the light receiving element side is It is branched into a number corresponding to , and connected to the corresponding pixel position. This method makes it possible to effectively utilize the extremely large number of pixels that a two-dimensional CCD has, making it possible to perform high-resolution stereoscopic imaging.

As is clear from the above description, the imaging method according to the present invention can have various applied configurations as shown below.

(1) Stereoscopic viewing is performed using the light receiving elements connected to the fiber bundles 9 and 11, and multiband observation is performed using the light receiving element connected to the fiber bundle 10.

(2) In the above configuration, switching reception such as stereoscopic viewing only, multiband observation only, etc. shall be performed by commands from the ground.

(3) The observation wavelength ranges of fiber bundles 9, 10, and 11 are the same, and between 9 and 11, between 10 and 11, and between 9 and 1
Obtain stereoscopic information by each between 0 and 0. Or,
One of these should be used as a redundant system and as a spare.

It should be noted that it is clear from the above description that the method of the present invention can also be applied to three-dimensional observation from a flying object such as an aircraft.

As described above, according to the present invention, a compact, lightweight, and highly reliable stereoscopic imaging system can be obtained with an extremely simple configuration.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram showing an example of a conventional stereoscopic imaging method, Fig. 2 is a conceptual diagram when a point directly below is imaged using the method shown in Fig. 1, and Fig. 3 is a conceptual diagram showing another example of the conventional stereoscopic imaging method. 4 is a conceptual diagram showing an embodiment of the stereoscopic imaging system according to the present invention, FIG. 5 is an enlarged perspective view showing an example of the configuration of the fiber bundle and light receiving element section in FIG. 4, and FIG. FIG. 4 is a block diagram of a satellite transmitter adopting the method shown in FIG. The figure is a partially enlarged perspective view showing the configuration of a fiber bundle and a light receiving element section when a two-dimensional CCD is used in the method of the present invention. In the figure, 1... Satellite, 2, 2'... Imaging device, 3, 4... Optical system, 5, 6... Photoelectric conversion element, 7... Movable mirror, 27... Wide angle optical system,
8... Image forming plane of optical system 27, 9-11... Fiber bundle, 12-14... Light receiving element, 15... Signal processing circuit, 16... Transmitting unit, 17... Transmitting antenna, 18... Receiving Antenna, 19... Reception demodulation unit, 20... Distribution circuit, 21 to 23... Distribution circuit, output signal of 20, 24, 26... Delay circuit,
25... Image processing recording section.

Claims (1)

[Claims] 1 In a three-dimensional imaging method that obtains a three-dimensional image of an object to be imaged, one aperture end is arranged within the same imaging plane of an imaging optical system in an imaging device that moves relative to the object to be imaged, and the other an optical fiber bundle whose aperture ends are coupled to a photoelectric conversion section of a multi-element photoelectric conversion element, at least two sets of aperture ends in the imaging plane are arranged in a one-dimensional arrangement, and the at least two sets of aperture end arrangements are arranged. are arranged substantially perpendicularly to the moving direction of the imaging device and parallel to each other to image at least the front and rear of the moving direction of the imaging device, and extract the captured data of these front and rear from the multi-element photoelectric conversion element. and obtaining the stereoscopic image based on this data.