KR100878888B1 - An aerial potography plotting instrument with a department for protecting gap having optical sensor - Google Patents

Abstract

An aerial photo plotting device including gap protecting part having optical sensor for obtaining geographic information is provided to perform reliable plotting operation by protecting a gap of an aerial photo in an aerial photo carrier. An aerial photo plotting device(100) including gap protecting part having optical sensor comprises an aerial photo carrier(110), a gap protecting part(130), a system for controlling temperature(150), a control part(170), and an image display part(190). The aerial photo carrier receives a pair of aerial photo positive films. The gap protecting part fixes a pair of aerial photo positive films in the aerial photo carrier, and is positioned in one side of the aerial photo carrier. The system for controlling temperature steadily maintains temperature of the aerial photo carrier. The control part includes an aerial photo measuring system and a stereo image processing system. The aerial photo measuring system generates an aerial photo model from a pair of aerial photo positive films, and measures a specific area by using the aerial photo model. The stereo image processing system processes geographic information measured from the aerial photo measuring system into a stereo image. The image display part displays the stereo image outputted from the control part. The gap protecting part includes an optical sensor, a first position control part, and a second position control part. The control part controls the first position control part and the second position control part.

Description

An Aerial Potography Plotting Instrument with a Department for Protecting Gap having Optical Sensor

The present invention relates to an apparatus for reading an aerial photo used for obtaining geographic information, and more particularly, to an aerial photographic injector having a play prevention part including an optical sensor.

The flasher refers to equipment for producing topographic maps using quantum film from aerial photographs. The projectors can be broadly classified into analog processors, analytical ones, and numerical ones.

The projector is basically composed of a stereo comparator and a coordinatograph. Servomotors and encoders are an important part of the components of the projector, and they are devices that control the automatic measurement of photographic tasks.

The lighter can calculate the mathematical model using the collinear conditional equation. The external inputs needed to solve the equation are the internal coordinates of the camera and the ground coordinates of the reference point, and the internal inputs are the coordinates measured by the projector itself.

From this data, the computer can calculate model coordinates and other useful results in real time. The projector sends the measured data to a coordinatograph for display on the screen or for printing or printing in hard copy form.

The drawing method is briefly described below. Various drawing methods using aerial photographs include a correction drawing method, an analysis drawing method, and a numerical drawing method.

Modified drawing method is a representative method of mechanical photogrammetry. It is a method of drawing a digital map by performing partial drawing on the area changed through aerial photographs and Dohwawon map, digitizing and merging it with existing digital map.

The analysis drawing method checks the existing numerical values directly on the screen of the computer connected to the projector. In other words, it is easy to confirm the correction factor through comparison with the aerial photo, and it is possible to directly produce the correction file for the updated contents. In the case of updating the digital map by photogrammetry, it is possible to convert large numbers of aerial photographs into the ground coordinate system at the same time.

Unlike the analytical drawing method, the numerical drawing method is a drawing operation using an image file. When updating the digital map by the numerical mapping method, an imaging process of aerial photographs is required. This can be achieved by photographing the first aerial photograph with a digital camera or by scanning the aerial photographic film with a high resolution scanner. The numerical mapping method may perform processes such as image registration, aerial triangulation, and digital terrain model (DTM) generation in finely divided unit pixels.

In general, when a drawing operation is performed, a pair of aerial photographs (left eye and right eye) of the area are first photographed. The operator can perform the drawing operation by displaying different portions on the digital map while checking numerical maps corresponding to the three-dimensional (three-dimensional image) aerial photographs and aerial photographs through stereoscopic glasses (polarizing screen and polarizing glasses).

However, when using the fuser, if a temperature difference occurs inside the fuser as the drawing operation is performed, play or stretching may occur in the aerial film. In other words, external deformations that occur in the aerial photo film may hamper the drawing performance. The drawing performance caused by the deformation of the aerial photography film may be at least 5000 times more error than normal.

The present invention has been made to solve the problems of the general technique as described above, an object of the present invention is to provide a fuser for performing an efficient drawing operation.

Another object of the present invention is to provide a fuser that can efficiently fix an aerial photogram film for precise drawing operation, and adjust the position of the photo film during the drawing operation.

It is still another object of the present invention to provide an aerial photographic fighter for producing a digital map for use in a geographic information system.

In order to solve the above technical problem, the present invention discloses an apparatus for reading an aerial photo. In particular, it discloses a structure of an aerial photographic fuser having a play prevention portion.

As an aspect of the present invention, an aerial photography injector having an automatic clearance prevention unit includes an aerial photography carrier for receiving a pair of aerial photography film filmed so that a predetermined area is overlapped in a specific region, and a pair of aerial photography film. The air gap prevention unit provided on one side of the aerial photo carrier to be fixed to the aerial photo carrier, a temperature control system for maintaining a constant temperature of the aerial photo carrier, aerosol model is generated from a pair of aerial photo positive film And a three-dimensional image output from the controller, including an aerial photographing system for surveying a specific area using an aerial photograph model and a three-dimensional image processing system for processing geographic information surveyed from the aerial photographing system into a three-dimensional image. It may include an image display unit. In this case, the play prevention unit may include an optical sensor for feeding back position information of the aerial photo quantizing film to the controller, a first position adjusting unit and a second position adjusting unit for adjusting the position of the aerial photo quantizing film. The controller may control the first position adjusting unit and the second position adjusting unit using the position information fed back from the optical sensor.

In one aspect of the present invention, the first position adjusting portion and the second position adjusting portion may be provided on the lower plate of the aerial photo carrier. In this case, the first position adjusting unit adjusts the position of the aerial photo quantum film in the direction in which the aerial photo quantum film is input, and the second position adjusting unit adjusts the position of the aerial photo quantum film in the vertical direction of the direction in which the aerial photo quantum film is input. I can adjust it. In addition, the first position adjusting unit and the second position adjusting unit may move up and down in the vertical direction of the bottom of the aerial photograph carrier.

In an aspect of the present invention, the first position adjusting unit and the second position adjusting unit may completely enter the inside of the aerial photo carrier lower plate when the top plate of the aerial photo carrier is completely in contact with the lower plate of the aerial photo carrier.

In an aspect of the present invention, the optical sensor may include a light emitting part generating light energy and a light receiving part converging light energy.

According to embodiments of the present invention has the following effects.

First, an efficient and precise drawing operation can be performed by using a drawing device reflecting the technical idea of the present invention.

Second, it is possible to carry out precise and reliable drawing operation by preventing the airborne play in the aerial photo carrier.

Third, it is possible to efficiently fix the aerial photo quantum film by using the gap prevention unit provided in the aerial photo carrier. If the aerial photo quantum film is not completely fixed to the aerial photo carrier, the position of the aerial photo quantum film may be adjusted by using the position adjusting unit provided in the fuser.

The present invention discloses an apparatus for reading aerial photographs used for obtaining geographic information. In particular, an embodiment of the present invention discloses an aerial photogram equipped with a play prevention part including an optical sensor.

The following embodiments combine the components and features of the present invention in a predetermined form. Each component or feature may be considered to be optional unless otherwise stated. Each component or feature may be embodied in a form that is not combined with other components or features. In addition, some components and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment.

In the description of the drawings, parts or accessories, which may obscure the gist of the present invention, are not described, and parts or accessories, which can be understood by those skilled in the art, are not described. These matters can be understood at the level of those skilled in the art. In addition, in the drawings of the present specification, the same part or a part performing a similar function is indicated using the same identification number.

Specific terms used in the following description are provided to help the understanding of the present invention, and the use of the specific terms may be modified in other forms without departing from the technical spirit of the present invention.

Geographic Information System (GIS) is an information system that integrates and processes geographic data that occupies spatial location and attribute data related to it, and efficiently collects various types of geographic information. The overall organization of hardware, software, geographic data, and human resources used to store, update, process, analyze, and output.

Geographic information system (GIS) is one of the information systems for efficiently utilizing the geographic information necessary for human life. GIS as used herein means an activity system consisting of interactions between the relevant components of the real world for the purpose of public use. An example of a GIS is a car. That is, a car is composed of several components, and can be regarded as a system for providing transportation by interaction between each component.

GIS broadly refers to an information system for a series of manipulations, from observation and collection of geographic information to preservation, analysis and output to support human decision making. At this time, the information system is a general process for making the information necessary for decision making, and includes the generation and the storage and analysis of the information. Therefore, an information system can represent a wide range of functions that analyze stored information and use the results of analysis in decision making from information generation, storage, and management functions such as observation and measurement of various information.

Numerical mapping refers to the operation of measuring the topographic features of survey aerial photographs or satellite images with numerical data by using an analytical or coordinate input device.

An aerial photogrammeter is a device that reads aerial photographs taken using digital photogrammetry equipment used in geographic information systems (GIS). In other words, the aerial photogrammeter relates to an aerial photographic model of aerial photographs taken through an aerial photographic camera, and a system that can read the differences between the two aerial photographs by superimposing the abbreviated figures.

A digital map refers to a drawing in which information of a paper map is digitized into a set of geometric figure elements or pixels in the form of points, lines, and planes. In addition, the digital map should be prepared in accordance with the standard format provided to the National Geographic Information Institute (NGII). The abbreviated state map (or read aid map) shows the survey results, the boundary of administrative districts, the place names, etc. for the surface situation to be displayed, and can be used as basic data in various fields such as land use development and statistical investigation. have.

FIG. 1 is a diagram showing a logical block diagram of an aerial photography fuser as an embodiment of the present invention.

Referring to FIG. 1, an aerial photography injector 100 having a clearance prevention unit including an optical sensor according to the present invention includes an aerial photograph carrier 110, a clearance prevention unit 130, a temperature control system 150, and a controller. And an image display unit 190.

The aerial photograph carrier 110 is a device for receiving an aerial photograph positive film. Of course, in addition to the aerial photographic film, various geographic numerical information and user information may be input.

A pair of aerial photographs constitute one aerial photograph model. For example, aerial photographs are shot two by one overlapping a certain portion of a specific area. The aerial photo carrier is the part that holds the aerial photo taken of a specific area for drawing purposes. Accordingly, the aerial photo carrier may be configured with a pair of aerial photo carriers on the left and right sides to receive a single aerial photo model and perform drawing.

The aerial photography fuser may include a clearance prevention unit 130 for preventing the clearance of the aerial photography positive film on the aerial photography carrier 110. The gap prevention part 130 is a part for minimizing the stretching or deformation occurring in the aerial photography positive film despite the impact or temperature change applied to the aerial photography.

Temperature control system 150 is a system for maintaining a constant temperature of the aerial photographic fuser. In particular, in an aerial photographic fuser, the temperature of the aerial photograph carrier on which the aerial photograph positive film is placed needs to be constant.

During the drawing operation, there may be a difference in the internal temperature of the aerial photography fuser. For example, a temperature difference between carriers on the left and right sides of an aerial photo carrier may occur, or a temperature of the entire carrier may increase.

In this case, since the temperature of the aerial photogram may be transferred to the aerial photogram positive film, slight play or stretching may occur in the aerial photogram film. This directly affects the drawing work. At least 5,000-fold difference in the drawing performance due to deformation caused by play or expansion of the aerial film is possible.

Therefore, it is a very important factor in the aerial photogramming operation that the temperature of the aerial photogram, especially the aerial photocarrier, is always constant, and it can be said that preventing the play of the aerial photogramming film is very important. In FIG. 1, the temperature control system 150 may perform a function of constantly maintaining the temperature of the aerial photogram and the aerial photo carrier.

In FIG. 1, the control unit 170 controls the aerial photograph carrier 110, the play prevention unit 130, the temperature control system 150, and the image display unit 170. The control unit 170 controls the automatic temperature control system for maintaining a constant temperature of the aerial photo carrier, generates an aerial photo model from a pair of aerial photo quantum film input to the aerial photo carrier, using the aerial photo model An aerial surveying system for surveying a specific area and a stereoscopic image processing system for processing the geographic information surveyed from the aerial surveying system into a stereoscopic image. The controller 170 may display the stereoscopic image output from the stereoscopic image processing system to the user through the image display unit 190.

In FIG. 1, since the gist of the present invention may be obscured, an aerial survey survey system and a stereoscopic image processing system are not illustrated in detail. However, if necessary, the aerial surveying system and the stereoscopic image processing system may use systems generally used in the art.

In addition, the controller 170 may control the play prevention unit 130 to fix the aerial photo quantum film when the aerial photo quantum film is input to the fuser (or the aerial photo carrier). In addition, the control unit 170 may control the temperature control system 150 to maintain a constant temperature of the aerial photography fuser, thereby increasing the precision of the aerial photography.

2 is a block diagram illustrating a play prevention part connected to one side of an aerial photo carrier according to another embodiment of the present invention.

In FIG. 2, the play prevention part 130 includes an optical sensor 220 for identifying the position of the aerial photo quantum film, a first position adjusting unit 240 and a second position 260 for adjusting the position of the aerial photo quantum film. ) May be included.

The aerial photo carrier 110 may include an upper carrier and a lower carrier. An aerial photo positive film can be fixed by placing an aerial photo positive film on the lower carrier and completely covering the top carrier on the lower carrier.

The optical sensor 220 may check whether the aerial photographic positive film is completely fixed to the aerial photograph carrier. The optical sensor 220 may be provided at one side of the aerial photo carrier. In addition, the optical sensor 220 may be provided at various positions of the aerial photo carrier. However, the optical sensor 220, in order to accurately determine the position of the aerial photographic film, when the aerial photographic film is in close contact with the aerial photograph carrier, the aerial photograph of the portion where the end of the aerial photographic film is located It is preferred to be located on the carrier bottom plate.

The optical sensor 220 may check whether the aerial photographic positive film is normally completely in close contact with the aerial photograph carrier. The optical sensor 220 may determine that the positive film is input when the aerial photo film reaches a predetermined sensing position. Specific operating principle of the optical sensor will be described later. The optical sensor 220 is connected to a control unit, and may feed back input state information of the aerial photographic film to the control unit.

2, the first position adjusting unit 240 is preferably provided in the same direction as the direction in which the aerial positive film is input. Therefore, the position of the aerial photo quantum film can be adjusted when the aerial photo quantum film is not normally input to the aerial photo carrier.

The second position adjusting unit 260 is preferably provided in a direction perpendicular to the direction in which the aerial positive film is input. If the position of the aerial photo quantum film is still adjusted by the first positioning unit, but still occurs when the aerial photo quantum film is free from the aerial photo carrier, the second positioning unit 260 resets the position of the aerial photo film. Adjust to eliminate play with aerial photo carriers.

The first position adjusting unit 240 and the second position adjusting unit 260 may be connected to the control unit and may be controlled by the control unit. The controller may control the first position adjusting unit 240 and the second position adjusting unit 260 by receiving feedback of the position information of the aerial photo quantum film from the optical sensor to prevent play and separation of the aerial photo quantum film.

3 is a view showing an example of an aerial photographic fuser to which embodiments of the present invention can be applied.

Fig. 3 (a) shows an example of an analytical-type drawing machine, and Fig. 3 (b) shows an example of a numerical drawing device for numerical drawing. The aerial photographic light reflector reflecting the technical idea of the present invention may be used in at least one of an analytical lighter and a numerical lighter as shown in FIGS. 3 (a) and 3 (b).

4 is a view showing an example of the first position adjusting unit and the second position adjusting unit as still another embodiment of the present invention.

4A illustrates an example of the first position adjusting unit 240. Referring to FIG. 4A, the first position adjusting unit 240 may be configured in the form of a cylinder or a very small roller. The first position adjusting unit 240 may adjust the position of the positive film by rotating in the direction A to B or the direction B to A in which the positive film is input.

4B illustrates an example of the second position adjusting unit 260. Referring to FIG. 4B, the second position adjusting unit 260 may have a cylindrical shape. However, the second position adjusting unit may be included in the carrier lower plate in a direction perpendicular to the rotation direction of the first position adjusting unit. For example, by rotating from D to C direction or C to D direction, the position of the positive film can be adjusted.

In addition, the first position adjusting unit and the second position adjusting unit can move the positive film with a minimum surface area by using a material having a large coefficient of friction such as rubber. Therefore, the position of the positive film can be adjusted efficiently. The first position adjusting unit and the second position adjusting unit have a form in which the carrier bottom plate is almost entirely included therein, and it is preferable that only a portion of the carrier film is exposed to the upper portion of the carrier lower plate.

In addition, since the first position adjusting portion and the second position adjusting portion can be moved up and down, when the carrier upper plate is in close contact with the carrier lower plate to fix the positive film, the first position adjusting unit and the second position adjusting unit are moved inside the carrier lower plate. By completely entering, the upper and lower carriers can be completely in contact with each other.

When the first position adjusting portion and the second position adjusting portion are configured in the form of a cylinder or a roller, a predetermined bar may be provided in the center direction of the first position adjusting portion and the second position adjusting portion. Therefore, the controller may drive the first position adjusting unit and the second position adjusting unit by rotating the bar. Of course, both ends of the bar may be connected to an elastic material so that the position adjusting units may perform vertical movement of the vertical movement as well as rotational movement.

However, when separation or play of the positive film occurs during the painting operation, the first position adjusting unit and the second position adjusting unit may adjust the position of the positive film again under the control of the controller.

5 is a perspective view illustrating an example of an aerial photo carrier including a clearance preventing part including an optical sensor as another embodiment of the present invention.

The aerial photo carrier 110 may include one carrier top plate and one carrier bottom plate. If the aerial photograph carrier 110 has a configuration including a left carrier and a right carrier (see FIG. 2), the left carrier and the right carrier may include a carrier upper plate and a carrier lower plate, respectively.

5 shows a case in which an aerial photograph carrier takes one configuration for ease of explanation. Of course, the structure of FIG. 5 may also be applied when the aerial photo carrier has left and right carriers.

Referring to FIG. 5, the play prevention unit 130 may be provided at a lower plate of the aerial photo carrier. The positions of the bottom of the aerial photo carrier are shown using the letters A, B, C and D, respectively, up, down, left and right. In the embodiments of the present invention, it is assumed that the aerial positive film is input in the direction A to B.

The lower plate of the aerial photo carrier may include one or more first positioning unit 240 and one or more second positioning unit 260. Referring to FIG. 5, since the aerial photography film is input to the carrier in a pair of left and right, the configuration may include a pair of first position adjusting units 240 on the upper and lower sides (for example, A and B directions). have. In addition, a configuration including a pair of second position adjusting units 260 on the left and right sides (for example, C and D directions) in the direction in which the positive film is input may be taken.

In FIG. 5, the optical sensor 220 is preferably provided on the B side in which the positive film is input. Of course, the optical sensor may be provided in at least one of the A, C and D directions. However, in the exemplary embodiments of the present invention, one or more optical sensors are positioned only in the B direction. Each optical sensor can be connected to the controller.

The optical sensor 220 may include a light emitting unit emitting light and a light receiving unit 222 converging the emitted light. The optical sensor may have a light emitting unit 224 having various kinds of light sources. In the embodiments of the present invention, all optical sensors (eg, laser sensors and infrared sensors) using light energy may be used.

When the positive film is input to completely cover the light emitting part of the optical sensor 220, the light emitted from the light emitting part is prevented from entering the light receiving part. The control unit may receive feedback of the position information of the positive film from all the optical sensors 220 provided in the carrier. In this case, the controller may determine that the positive film is normally positioned in the aerial photograph carrier only when the light emitted from the light emitting parts of the at least one optical sensor does not enter the light receiving part.

Referring back to FIG. 5, the optical sensor may feed back the position of the positive film to the controller. If the positive film is not normally input to the carrier and receives light from the light receiving unit of the specific optical sensor, the controller determines that the positive film is not normally input, and the first position adjusting unit 240 and the second position adjusting unit 260. By controlling the position of the positive film can be adjusted.

Hereinafter, the operation principle of the fuser shown in FIG. 5 will be described.

First, the positive film is input to the aerial photo carrier. The optical sensor provided at a predetermined position of the aerial photograph carrier may feed back the position of the positive film to the controller. When the aerial photography film is completely in contact with the carrier, the control unit may completely fix the film by covering the carrier top plate with the carrier bottom plate.

If the position of the positive film is not completely in contact with the predetermined position of the carrier, the optical sensor may feed back the position of the positive film to the controller. The controller may determine the current position of the positive film by receiving the feedback of the positive film. Therefore, the control unit may prevent the play of the positive film by adjusting the first position adjusting unit and / or the second position adjusting unit to eliminate the portion where the play occurs.

For example, when the positive film is not completely input in the input direction, the control unit drives the first position adjusting unit to adjust the position of the positive film. If the clearance of the positive film disappears through this process, it starts to cover the top of the carrier and start the aerial photograph. If the play of the positive film does not disappear even if the first position adjusting unit is driven, the control unit drives the second position adjusting unit to adjust the position of the positive film so that the positive film is positioned at a predetermined position for performing the drawing operation. Can be.

While the control unit controls the first position adjusting unit and the second position adjusting unit, the control unit can continuously receive the position of the positive film from the optical sensor. The control unit may precisely control the position of the positive film using the feedback information of the positive film.

If the position of the positive film is positioned in the normal position by controlling the first position adjusting unit and the second position adjusting unit, the control unit may completely fix the aerial photogram positive film by bringing the upper aerial photograph carrier plate into close contact with the lower aerial photograph carrier.

In another embodiment of the present invention, the control unit and the optical sensor may operate while the drawing operation is performed. If the separation or clearance of the positive film occurs during the painting operation, the control unit may know that the position of the positive film is changed from the optical sensor. Therefore, the controller may stop the drawing operation and control the first position adjusting unit and the second position adjusting unit to adjust the position of the positive film.

The invention can be embodied in other specific forms without departing from the spirit and essential features of the invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention. It is also possible to form embodiments by combining claims that do not have an explicit citation in the claims or to include them as new claims by post-application correction.

FIG. 1 is a diagram showing a logical block diagram of an aerial photography fuser as an embodiment of the present invention.

2 is a block diagram illustrating a play prevention part connected to one side of an aerial photo carrier according to another embodiment of the present invention.

3 is a view showing an example of an aerial photographic fuser to which embodiments of the present invention can be applied.

4 is a view showing an example of the first position adjusting unit and the second position adjusting unit as still another embodiment of the present invention.

5 is a perspective view showing an example of an aerial photo carrier including a play prevention part as another embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

100: aerial photo fuser 110: aerial photo carrier

130: clearance prevention part 150: temperature control system

170: control unit 190: image display unit

220: optical sensor 222: light receiving unit

224: light emitting unit 240: first position adjusting unit

260: second position adjusting unit

Claims (6)

In the aerial photographic injector having a play prevention part including an optical sensor, An aerial photo carrier for receiving a pair of aerial photo quantum films photographed such that a predetermined area overlaps in a specific region; A gap prevention part provided at one side of the aerial photo carrier to press-fit the pair of aerial photogram positive film to the aerial photo carrier; A temperature control system for maintaining a constant temperature of said aerial photo carrier; An aerial photographic model is generated from the pair of aerial photographic quantum films, and an aerial photographic survey system for surveying the specific area using the aerial photograph model and a stereoscopic image for processing geographic information surveyed from the aerial photographic survey system as a stereoscopic image. A control unit including an image processing system; And An image display unit for displaying a stereoscopic image output from the control unit, The play prevention part includes an optical sensor for feeding back position information of the aerial photography film to the controller, a first position adjusting section and a second position adjusting section for adjusting the position of the aerial photography film, And the control unit controls the first position adjusting unit and the second position adjusting unit using the position information fed back from the optical sensor. The aerial photography of claim 1, wherein the first positioning unit and the second positioning unit are provided on a lower plate of the aerial photo carrier. The method of claim 2, wherein the first position adjusting unit adjusts the position of the aerial photo quantum film in the direction in which the aerial photo quantum film is input, And the second position adjusting unit adjusts the position of the aerial photogramming film in a vertical direction of the direction in which the aerial photogramming film is input. The aerial photography of claim 3, wherein the first position adjusting unit and the second position adjusting unit move upward and downward in a vertical direction of the lower plate of the aerial vehicle carrier. The air conditioner of claim 4, wherein the first position adjusting unit and the second position adjusting unit completely enter the inside of the lower aerial group when the upper plate of the aerial photo carrier is in close contact with the lower plate of the aerial photo carrier. An aerial photographic fuser having a play prevention part including an optical sensor. The light emitting device of claim 1, wherein the optical sensor comprises: a light emitting unit generating light energy; And a gap preventing part including an optical sensor including a light receiving part converging the light energy.

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