Method for projecting light points, digital planetarium system, projection control device and its program

Abstract

To enable excellent projection to be easily achieved in a multi-projection system.SOLUTION: A projection method according to the present invention is a method of projecting a plurality of light spots, comprising acquiring light spot data having information on a position and a brightness of each of the plurality of light spots, determining the allocation as to which light spot group image includes each of the light sports to be projected; when the position of the light spot is in a duplicate region, based on predetermined allocation conditions that are designated for every light spot and are not all the same, determining the allocation as to which light spot image including the duplicate region includes the light spot, depicting, based on the respective positions, luminous intensities, and allocation, each of the light spots to be projected on at least any one of the light spot group images to produce a plurality of pieces of light spot group image data, and projecting each of the light spot group images on each of the projectors based on each piece of the light spot group image data.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for projecting a light spot, a digital planetarium system, a projection control device, and a program therefor. [Background technology]

[0002] Digital planetariums using projectors are well known. In digital planetariums, a multi-projection system using multiple projectors projects high-resolution images and stars onto the entire surface of a dome-shaped screen. Using multiple projectors allows for the reproduction of clearer, higher-resolution images and a starry sky than using a single projector.

[0003] In multi-projection systems, efforts are made to make the seams between images projected by different projectors less noticeable. For example, Patent Document 1 discloses the following technology. This technology precisely aligns adjacent projected images so that they overlap slightly. In the overlapping areas, the brightness of each image is gradually changed so that it decreases toward the edge, and the brightness resulting from the overlap is made equal to the brightness when the images are projected by a single projector. In this way, the seams become less noticeable.

[0004] With this technology, it is important to align the projections accurately, as any misalignment will result in the image appearing double where the images overlap. This misalignment is particularly noticeable with the tiny dots of stars projected by digital planetariums. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-260932 Summary of the Invention [Problem to be solved by the invention]

[0006] In a multi-projection system, the burden of accurately aligning adjacent projected images is significant, and there is a demand for reducing this burden.

[0007] An object of the present invention is to easily achieve good projection in a multi-projection system. [Means for solving the problem]

[0008] According to one aspect of the present invention, a projection method projects a plurality of light points by having each of a plurality of projectors installed so as to have an overlapping area where projection areas of the plurality of projectors overlap, and includes: acquiring light point data including information on the position and brightness of each of the plurality of light points; determining an allocation of which of the light point cloud images each of the projected light points will be included in; when the position of a light point falls in the overlapping area, determining an allocation of which of the light point cloud images including the overlapping area each of the light points will be included in based on predetermined allocation conditions that are specified for each of the light points and are not all the same; drawing each of the projected light points in at least one of the light point cloud images based on each of the position, brightness, and allocation, and generating a plurality of light point cloud image data that is data of a plurality of the light point cloud images; and projecting each of the light point cloud images from each of the projectors based on each of the light point cloud image data. [Effects of the Invention]

[0009] According to the present invention, good projection can be easily achieved in a multi-projection system. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an outline of an example of the configuration of a digital planetarium according to an embodiment. [Figure 2]FIG. 2 is a diagram showing a schematic diagram of a state in which images are projected by two projectors. [Figure 3] FIG. 3 is a flowchart showing an outline of an example of the operation of the projection control device according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing an outline of an example of the structure of light spot data according to the first embodiment. [Figure 5] FIG. 5 is a schematic diagram for explaining the operation according to the second embodiment. [Figure 6] FIG. 6 is a flowchart showing an outline of an example of the operation of the projection control device according to the second embodiment. [Figure 7] FIG. 7 is a diagram showing an outline of an example of the structure of light spot data according to the third embodiment. [Figure 8] FIG. 8 is a diagram that schematically shows how the first star and the second star move together near the overlapping region to the right, crossing the boundary line. [Figure 9] FIG. 9 is a flowchart showing an outline of an example of the operation of the projection control device according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] [First embodiment] <Digital Planetarium Configuration> A first embodiment will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of an example configuration of a digital planetarium system 1 according to the first embodiment. The digital planetarium system 1 of this embodiment projects images of a starry sky, scenery, and other images onto a dome-shaped screen 50 provided on the inner surface of a hemispherical dome. In order to project clear, high-resolution images of a starry sky and the like onto the dome-shaped screen 50, the digital planetarium system 1 is equipped with multiple projectors 40. Images are projected onto the entire surface of the dome-shaped screen 50 by so-called multi-projection using the multiple projectors 40.

[0012] Projector 40 is a projector similar to a general video projector. Projector 40 generates image light representing an image by modulating light guided from a light source of projector 40 based on image data input to projector 40. Projector 40 projects this image light onto dome-shaped screen 50 via a projection lens.

[0013] Digital planetarium system 1 includes a data providing device 30 and a projection control device 10. Data providing device 30 provides original data for images to be projected onto a dome-shaped screen 50. Projection control device 10 generates data for images to be projected by each projector 40 based on the original data provided by data providing device 30, provides the image data to each projector 40, and controls the operation of each projector 40.

[0014] The images projected by the digital planetarium system 1 may include images of a starry sky, images including a night view and the starry sky, images of constellations superimposed on a starry sky, images of a spaceship and the starry sky, and various other images. The data providing device 30 provides the original data projected by the digital planetarium system 1. The images projected by the digital planetarium system 1 include at least images of light points such as stars. The data providing device 30 provides light point data including information on the position and brightness of each of a plurality of light points as original data representing light points such as stars and planets. The light point data is not limited to light points representing stars, but may also include data on light points related to light sources included in a night view. The data providing device 30 may also provide image data including information on the brightness value of each pixel as original data representing a night view, etc. The image data may be a still image or a video. The light point data may also be data that changes over time.

[0015] Original data for the image is input from a data providing device 30 to the projection control device 10. Based on the input original data, the projection control device 10 creates image data representing a projected image to be input to the projector 40. The data providing device 30 may be a video playback device, a computer, or other device. The data providing device 30 and the projection control device 10 may be connected by wire or wirelessly, or the data providing device 30 may be located in a remote location and connected to the projection control device 10 via a network.

[0016] The projection control device 10 includes elements and devices such as a processor, such as a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or a graphics processing unit (GPU), as well as memory and various interfaces. The processor performs predetermined operations using a program or hardware. The projection control device 10 includes functions such as a data acquisition unit 12, an allocation determination unit 14, an image generation unit 16, and an image output unit 18.

[0017] As will be described in detail later, for example, the data acquisition unit 12 acquires light spot data from the data providing device 30, including information on the position and brightness of each of a plurality of light spots, as information representing stars. The allocation determination unit 14 determines the allocation of each light spot to be projected by which of the plurality of projectors 40. Note that a light spot that is included in the light spot data but does not need to be projected, such as a light spot that is outside the projection areas of any of the plurality of projectors 40, may not be assigned to any of the projectors 40. As a result, the light spot is not projected. In particular, when a light spot is located within an overlapping area, which is an area where images are projected by multiple projectors 40 as described below, the light spot can be projected by any of the projectors 40. When a light spot is located within the overlapping area, the allocation determination unit 14 determines which projector to use to project the light spot based on predetermined allocation conditions. Here, multiple allocation conditions are provided, and one of the multiple allocation conditions is specified for each light spot. In other words, the allocation conditions are not the same for all light points, but multiple light points are divided into multiple groups with different allocation conditions, and light points belonging to different groups have different allocation conditions. In this way, the allocation determination unit 14 determines the allocation of a light point located within an overlapping area to be included in one of multiple images including the overlapping area.

[0018] The image generation unit 16 renders each light point in an image projected by at least one of the projectors 40 based on the position and brightness included in the light point data for each light point to be projected and the allocation determined by the allocation determination unit 14. In this way, the image generation unit 16 generates light point cloud image data, which is data for an image including light points, for each projector 40. That is, the image generation unit 16 generates multiple pieces of light point cloud image data. The image output unit 18 causes each projector 40 to project a light point cloud image based on each of the light point cloud image data.

[0019] In this way, under the control of the projection control device 10, the projector 40 projects images of light points such as stars based on the data provided by the data providing device 30. Not only images of stars, but other images such as landscapes and imaginary images can also be projected by the projector 40. That is, when the data is provided from the data providing device 30, the projection control device 10 assigns which projector 40 to use for projection based on the position. The projection control device 10 inputs the corresponding image data to each projector 40. The projector 40 projects an image based on the input image data. Of course, image data in which other images such as landscapes and imaginary images are superimposed on the image of light points may be created, and an image based on this may be projected.

[0020] <Digital Planetarium System Operation> The following describes the operation of the digital planetarium system 1. For simplicity, the following description will be given taking as an example a case where images are projected using two projectors 40. Even if the number of projectors 40 increases, the operation of the digital planetarium system 1 remains the same.

[0021] FIG. 2 is a diagram schematically illustrating a case where images are projected by two projectors, a first projector 41 and a second projector 42. The area on the dome-shaped screen 50 onto which an image is projected by the first projector 41 is referred to as a first area 61. The area on the dome-shaped screen 50 onto which an image is projected by the second projector 42 is referred to as a second area 62. In this example, the first area 61 is located on the left side, and the second area 62 is located on the right side, adjacent to each other. The first area 61 and the second area 62 partially overlap, and this area is referred to as an overlapping area 65. Furthermore, the area of ​​the first area 61 excluding the overlapping area 65 is referred to as a first exclusive area 63. The first exclusive area 63 is an area onto which an image is projected only by the first projector 41. The area of ​​the second area 62 excluding the overlapping area 65 is referred to as a second exclusive area 64. The second exclusive area 64 is an area onto which an image is projected only by the second projector 42. The overlapping area 65 is an area onto which an image is projected by both the first projector 41 and the second projector 42. Images are projected onto the first exclusive area 63, the overlapping area 65, and the second exclusive area 64 by two projectors, the first projector 41 and the second projector 42. The image projected by the first projector 41 will be referred to as the first image, and the image projected by the second projector 42 will be referred to as the second image.

[0022] In the example shown in FIG. 2, an image including nine stars, from the first star S1 to the ninth star S9, is projected onto the first exclusive area 63, the overlapping area 65, and the second exclusive area 64. The first star S1, the second star S2, and the third star S3 are included in the first exclusive area 63, and therefore are included in the first image projected by the first projector 41. The eighth star S8 and the ninth star S9 are included in the second exclusive area 64, and therefore are included in the second image projected by the second projector 42. The fourth star S4, the fifth star S5, the sixth star S6, and the seventh star S7 are included in the overlapping area 65, and therefore are included in the first image, the second image, or both images based on the allocation conditions.

[0023] In the example shown in FIG. 2, three boundary areas, namely, a first boundary area 71, a second boundary area 72, and a third boundary area 73, are provided within the overlap area 65 for the allocation conditions. Furthermore, one of the first boundary area 71, the second boundary area 72, and the third boundary area 73 is assigned to each star, for example, randomly. In this example, when each star is within the overlap area 65, the star is included in the first image when it is located to the left of the boundary area assigned to that star, and is included in the second image when it is located to the right. When the star is located within the boundary area assigned to that star, the star is included in both the first image and the second image, and its brightness is adjusted so that the sum of the brightness in the first image and the brightness in the second image is the brightness of the star. Furthermore, the brightness is adjusted so that the brightness in the first image is higher toward the left side of the boundary area and the brightness in the second image is higher toward the right side of the boundary area. Of course, any number of boundary areas may be used. Furthermore, the allocation of brightness of stars within a boundary area is not limited to the example shown here, and other methods may be used.

[0024] In the example described here, the fourth star S4 has the second boundary area 72 specified as its boundary area, the fifth star S5 has the first boundary area 71 specified as its boundary area, the sixth star S6 has the third boundary area 73 specified as its boundary area, and the seventh star S7 has the second boundary area 72 specified as its boundary area. In the state shown in FIG. 2, the fourth star S4 is included in the first image because it is to the left of the specified second boundary area 72. The fifth star S5 is included in the second image because it is to the right of the specified first boundary area 71. The seventh star S7 is included in the second image because it is to the right of the specified second boundary area 72.

[0025] The sixth star S6 is included in both the first image and the second image because it is within the specified third boundary area 73. The brightness of the image of the sixth star S6 projected by the first projector 41 and the brightness of the image projected by the second projector 42 are both darker than the brightness of the image of the sixth star S6 when projected by a single projector 40. The brightness of the image projected by the first projector 41 and the brightness of the image projected by the second projector 42 are adjusted so that the image of the sixth star S6 projected by the first projector 41 and the image of the sixth star S6 projected by the second projector 42 overlap and exactly represent the brightness of the sixth star S6.

[0026] The ratio between the brightness of the sixth star S6 in the first image and the brightness of the sixth star S6 in the second image is determined, for example, by the ratio between the distance from the left edge EL and the distance from the right edge ER of the third boundary region 73. For example, when the sixth star S6 is located at a position that divides the distance from the left edge EL to the right edge ER at a ratio of 2:8, the brightness of the sixth star S6 in the first image is set to 80% of the brightness indicated by the light spot data, and the brightness of the sixth star S6 in the second image is set to 20% of the brightness indicated by the light spot data.

[0027] 3 is a flowchart showing an outline of an example of the operation of the projection control device 10. The operation described here is an example in which the projection control device 10 acquires light spot data related to stars to be projected from the data providing device 30, creates light spot cloud image data related to the stars based on the light spot data, and outputs it to the projector. Here, the projection control device 10 creates, as the light spot cloud image data, data of a first image to be projected by the first projector 41 and data of a second image to be projected by the second projector 42, as in the example shown in FIG.

[0028] In step S101, the projection control device 10 acquires light spot data indicating information about stars to be projected from the data providing device 30. The light spot data includes information about the position and brightness of at least each of a plurality of light spots (stars) required to render a star image.

[0029] FIG. 4 is a diagram illustrating an example of the structure of light spot data. In this example, for each of n stars, information is included: coordinates indicating the position where the star should be drawn; a value indicating the brightness of the star; the color of the star to be drawn; and a boundary number indicating which boundary area to use. The star coordinates may be coordinates on the screen of the projected image, astronomical coordinate values ​​such as equatorial coordinates, or coordinates converted from astronomical coordinate values ​​to on-screen coordinates by coordinate transformation. When the coordinates are astronomical coordinate values, the projection control device 10 calculates the on-screen coordinates by a predetermined coordinate transformation based on these coordinate values. Note that this is just an example, and the data may be modified as appropriate, for example, by omitting star color information or adding other information. Here, an example is shown in which the light spot data includes independent boundary number information. However, the boundary area to use may be determined by the projection control device 10 calculating it according to a predetermined rule based on the data number (e.g., 1 to n). In this case, the boundary number information is essentially included in the data number.

[0030] In step S102, the projection control device 10 initializes various parameters when creating an image. For example, a variable i indicating the star number is set to 1, and the first image and the second image are initialized.

[0031] In step S103, the projection control device 10 sets the star with star number i as the processing target and reads the data of star number i. In step S104, the projection control device 10 determines whether the area in which the star is located is the first exclusive area 63, the second exclusive area 64, or the overlap area 65, based on the coordinate information of the star with star number i. If it is determined that the area in which the star is located is the first exclusive area 63, the processing proceeds to step S105. In step S105, the projection control device 10 draws the star with star number i in the first image based on its coordinates, brightness, color, etc. Then, the processing proceeds to step S110.

[0032] The simplest method for drawing stars is to draw a circle with a diameter calculated based on the square root of the brightness value at the appropriate position. Color information is used in this process. For example, when the calculated circle diameter is one pixel or greater, the brightness value of the circle is set to its maximum value, while when the diameter is less than one pixel, the brightness value of that pixel is changed according to the brightness. When the circle diameter is one pixel or greater, the brightness value does not have to be set to its maximum value; each pixel may have a different brightness value. In this way, a star image is created, whose brightness is expressed by its area and brightness. Note that the shape of the light spot may be appropriately changed, such as to use an ellipse instead of a circle, to avoid distortion on the curved surface of the dome-shaped screen 50. The brightness of the light spot may also change over time, thereby expressing the twinkling of the star due to atmospheric fluctuations.

[0033] In step S104, when it is determined that the area in which the star with star number i is located is the second exclusive area 64, the process proceeds to step S106. In step S106, the projection control device 10 draws the star with star number i in the second image. Thereafter, the process proceeds to step S110.

[0034] If it is determined in step S104 that the area in which the star with star number i is located is the overlap area 65, the process proceeds to step S107. In step S107, the projection control device 10 performs boundary determination based on the boundary number of the star. If it is determined that the position of the star with star number i is on the first area side, to the left of the boundary area specified by the boundary number, the process proceeds to step S105, where the projection control device 10 draws the star with star number i in the first image. Thereafter, the process proceeds to step S110. If it is determined that the position of the star with star number i is on the second area side, to the right of the boundary area specified by the boundary number, the process proceeds to step S106, where the projection control device 10 draws the star with star number i in the second image. Thereafter, the process proceeds to step S110.

[0035] If it is determined that the position of the star with star number i is within the boundary area specified by the boundary number, the process proceeds to step S108. In step S108, the projection control device 10 determines a brightness ratio for the position of the star with star number i based on the ratio of the distance from the left edge EL to the distance from the right edge ER. In step S109, the projection control device 10 draws the star with star number i in the first image and the second image based on the determined brightness ratio. For example, when the position of the star with star number i is at a position that divides the distance from the left edge EL to the right edge ER at a ratio of 2:8, the projection control device 10 sets the brightness in the first image to 80% of the original brightness and the brightness in the second image to 20% of the original brightness. Then, the process proceeds to step S110.

[0036] In step S110, the projection control device 10 adds 1 to the variable i indicating the star number. In step S111, the projection control device 10 determines whether the variable i is greater than the number n of stars included in the light spot data. If the variable i is not greater than the number n of stars, the process returns to step S103. In this way, n stars are rendered in the first image or the second image.

[0037] If it is determined in step S111 that the variable i is greater than the number n of stars, the process proceeds to step S112. That is, when all the stars have been rendered in the first image or the second image, in step S112, the projection control device 10 outputs the data of the created first image to the first projector 41 and outputs the data of the created second image to the second projector 42. The first projector 41, which has acquired the data of the first image, projects the first image onto the dome-shaped screen 50. The second projector 42, which has acquired the data of the second image, projects the second image onto the dome-shaped screen 50. Thereafter, the process returns to step S101.

[0038] By repeating the above operation, images representing stars are created one after another based on the updated light spot data, and the images representing stars are projected onto the dome-shaped screen 50.

[0039] According to the digital planetarium system 1 of this embodiment, when a starry sky is projected using a multi-projection system with multiple projectors 40, even if slight misalignment occurs in the projection areas of the multiple projectors 40, the boundary area where the images are projected by the multiple projectors 40 is narrower than the overlap area 65, so the area where the stars appear double is narrow. As a result, the unnatural phenomenon of stars appearing double across the entire overlap area 65 does not occur. Furthermore, because the boundary area is different for each star, the double areas do not stand out as being lined up in a straight line. Furthermore, because the boundary area is different for each star, even when projecting images of moving stars, there is no misalignment when all the stars cross a boundary line simultaneously or one after another. In this way, the digital planetarium system 1 can project a starry sky that appears natural to the eye.

[0040] In a multi-projection system using multiple projectors, if the images projected by the multiple projectors are accurately aligned in the overlapping area, problems do not occur in the overlapping area. However, even a slight deviation in the projection position can cause the projected images to shift, resulting in situations such as double images. Such deviations can occur due to slight deviations in the adjustment of the projection area or changes in the shape of the projectors or dome screen over time.

[0041] Generally, when adjusting the position of the projection area, the installer uses software to manually adjust the projector when installing the projector, or a camera is used to photograph the projection area and then mechanically adjust it based on the results of analyzing the positional relationship. However, manual adjustment requires a great deal of labor from specialized technicians with specialized skills. Furthermore, automatic calibration using a camera takes a long time, and the projection system cannot be used during the calibration process. For this reason, even automatic calibration has difficulty addressing positional deviations that can occur during screening due to factors such as temperature changes.

[0042] Even if there is a misalignment in the projection position in the overlapping area, it is not very noticeable if the projected image is a typical image such as a landscape or a person. However, if a collection of fine dots is projected, such as an image of a starry sky, the projected image will look extremely unnatural, with stars appearing double in the overlapping area.

[0043] When misalignment occurs, narrowing the overlapping area can be considered to minimize the appearance of double stars. However, while narrowing the overlapping area is fine when the projected stars are stationary, if the stars are moving, the position of the stars will appear to change suddenly at the boundary of the overlapping area, making the overlapping area more noticeable and making the projected image look extremely unnatural.

[0044] In contrast, with the digital planetarium system 1 according to this embodiment, the boundary area is narrower than the overlap area 65, so the area in which the stars appear double is narrower, and because the boundary area differs depending on the star, the misalignment is not noticeable even when projecting an image of a moving star. In this way, the digital planetarium system 1 can project a starry sky that looks natural.

[0045] [Variations] In the above example, a boundary area is randomly assigned to each star in advance. However, this is not limiting. The assignment of a boundary area to each star may be determined according to a predetermined rule based on the coordinates of the star. Alternatively, the assignment of a boundary area to each star may not be predetermined and may be changed dynamically.

[0046] In the above example, the boundary region has a width, but the boundary region may not have a width and the area of ​​the boundary region may be zero. In other words, the boundary region may be a boundary line.

[0047] In the above example, the allocation of brightness to the first and second images is determined according to the position within the boundary area, but this is not limiting. For example, a star may be drawn in both the first and second images for a predetermined time after the positional relationship between the star's position and the boundary area satisfies a predetermined condition, such as when the star enters the boundary area or is located at the center of the boundary area. The brightness of the star's image at that time may be allocated between the first and second images based on the elapsed time after the predetermined condition is met.

[0048] [Second embodiment] A second embodiment will be described. Here, differences from the first embodiment will be described, and the same parts will be assigned the same reference numerals and their description will be omitted. In the first embodiment, the boundary area was fixed. In contrast, in the second embodiment, the position of the boundary area changes depending on the direction of movement of the video.

[0049] In this embodiment, the case where the boundary region has no width and its area is zero, that is, the case where the boundary region is a boundary line, will be described as an example. However, this is not limited to this, and the same applies even if the boundary region has width, as in the first embodiment.

[0050] The operation according to this embodiment will be described with reference to the schematic diagram shown in FIG. 5. In this embodiment, as shown in FIG. 5(a), a boundary line 76, which is a boundary area with no width set for each star S, is provided within the overlapping region 65. In FIG. 5(a), the boundary line 76 specified for the illustrated star S is shown, but multiple boundary lines are set, and one of the boundary lines is specified for each star. Whether the star S is drawn in the first image or the second image is determined based on the position of the star S relative to the boundary line 76. In principle, when the star S is located to the left of the boundary line 76, the star S is drawn in the first image. When the star S is located to the right of the boundary line 76, the star S is drawn in the second image. Note that in FIG. 5, stars S drawn in the first image are schematically shown as white circles, and stars drawn in the second image are schematically shown as black circles. Here, in this embodiment, particularly in an image in which the star S is moving to the right, a right-shift boundary line 77 corrected to shift the star S to the right of the original boundary line 76 is used as the determination criterion.

[0051] Therefore, as shown schematically in FIGS. 5(b) to (e), when the star S is located to the left of the right-shift boundary line 77, the star S is drawn in the first image. Due to slight fluctuations in software parameters, etc., the star S may move back and forth across the boundary line 76 in data processing, as shown in FIGS. 5(c) to (d). In such cases, if the original boundary line 76 is used as the determination criterion, the star S may change slightly, sometimes being included in the first image and sometimes being included in the second image. In contrast, in this embodiment, such small changes do not occur due to fluctuations on the boundary line 76.

[0052] When the star S, as shown schematically in FIG. 5(f), moves to the right of the right-shift boundary line 77, the star S is rendered in the second image, not the first image. Here, when the star S moves to the right of the right-shift boundary line 77, the boundary line used as the reference for judgment is returned to the original boundary line 76, not the right-shift boundary line 77. As a result, even if the position of the star S oscillates on the right-shift boundary line 77, as shown schematically in FIGS. 5(f) to 5(g), the position of the star S is to the right of the boundary line 76, so the star S does not fluctuate between being included in the second image and being included in the first image. When the star S continues to move to the right, as shown in FIG. 5(h), the star S continues to be to the right of the boundary line 76, so the star S is included in the second image.

[0053] The same applies when the star S moves to the left. When the star S moves to the left, the left-shift boundary line corrected so that the boundary line 76 is shifted to the left is used as the criterion for judgment.

[0054] 6 is a flowchart outlining an example of the operation of the projection control device 10 according to this embodiment. With reference to this flowchart, the outline of the operation of the projection control device 10 when a star is moving to the right or left will be described.

[0055] In step S201, the projection control device 10 initializes various parameters. These parameters include values ​​indicating the previous coordinates of each star. In step S202, the projection control device 10 acquires light spot data indicating information about the stars to be projected from the data providing device 30. In step S203, the projection control device 10 initializes various parameters when creating an image. For example, a variable i indicating the star number is set to 1, and the first image and the second image are initialized. In step S204, the projection control device 10 sets the star with star number i as the processing target and reads the data of star number i.

[0056] In step S205, the projection control device 10 determines the direction of movement of the star. Here, information regarding the direction of movement of the star may be included in the light spot data, or the direction of movement of the star may be derived based on the previous coordinates of the star. If the movement is to the right, the process proceeds to step S206. In step S206, the projection control device 10 determines, based on past history, whether the star with star number i has already entered the second area to the right of the right-shift boundary line, which is obtained by shifting the boundary line to the right from the original boundary line. If the star is in the second area, the process proceeds to step S210. If the star is not in the second area, the process proceeds to step S207. In step S207, the projection control device 10 shifts the boundary line to the right from the original boundary line, making the boundary line the right-shift boundary line. Then, the process proceeds to step S210.

[0057] If it is determined in step S205 that the movement direction is a leftward movement, the process proceeds to step S208. In step S208, the projection control device 10 determines, based on past history, whether the star with star number i has already entered the first area to the left of the left-shift boundary line, which is obtained by shifting the boundary line to the left from the original boundary line. If it has entered the first area, the process proceeds to step S210. If it has not entered the first area, the process proceeds to step S209. In step S209, the projection control device 10 shifts the boundary line to the left from the original boundary line, and sets the boundary line as the left-shift boundary line. Thereafter, the process proceeds to step S210.

[0058] In step S210, the projection control device 10 determines whether the star with star number i is on the first region side or the second region side of the boundary line. The boundary line that serves as the basis for this determination is the original boundary line or a boundary line shifted to the right or left from the original boundary line, determined as described above based on the original boundary line specified for each star.

[0059] When it is determined that the area in which the star with star number i is located is on the first area side, the process proceeds to step S211. In step S211, the projection control device 10 draws the star with star number i in the first image. Thereafter, the process proceeds to step S213. On the other hand, when it is determined that the area in which the star with star number i is located is on the second area side, the process proceeds to step S212. In step S212, the projection control device 10 draws the star with star number i in the second image. Thereafter, the process proceeds to step S213.

[0060] In step S213, the projection control device 10 records information about the current coordinates of the star with the current star number i as the previous coordinates based on the position of the star. In step S214, the projection control device 10 adds 1 to the variable i indicating the star number. In step S215, the projection control device 10 determines whether the variable i is greater than the number n of stars included in the light point data. If the variable i is not greater than the number n of stars, the process returns to step S204. In this way, n stars are rendered in the first image or the second image.

[0061] If the variable i is greater than the number n of stars, the process proceeds to step S216. In step S216, the projection control device 10 outputs the data of the created first image to the first projector 41, and outputs the data of the created second image to the second projector 42. The first projector 41, which has acquired the data of the first image, projects the first image onto the dome-shaped screen 50. The second projector 42, which has acquired the data of the second image, projects the second image onto the dome-shaped screen 50. The process then returns to step S202. By repeating the above operations, images representing stars are successively created based on the updated light spot data, and the images representing the stars are projected onto the dome-shaped screen 50.

[0062] In this embodiment, by shifting the boundary line, even if there is a slight fluctuation in software parameters, it is possible to avoid unnatural projections caused by small changes in the projection of the same star between the first projector 41 and the second projector 42. In this way, the digital planetarium system 1 can project a starry sky that looks natural.

[0063] [Third embodiment] The third embodiment will be described. Differences from the first and second embodiments will be described below, and the same parts will be assigned the same reference numerals and their description will be omitted. In the first and second embodiments, the allocation conditions used to determine whether each star included in the overlapping region 65 should be included in the first image or the second image are that one of a plurality of boundary regions is designated for each star, and the allocation is determined based on the positional relationship between the boundary region and the star. In contrast, in the third embodiment, the delay time after crossing a boundary line is designated for each star as an allocation condition, and the allocation is determined based on the relationship between the elapsed time after crossing the boundary line and the designated delay time. Here, the delay time is designated for each star, and the delay time is not the same for all stars; while some stars have the same delay time, the delay time may differ for each star.

[0064] FIG. 7 is a diagram illustrating an example of the structure of light spot data according to the third embodiment. In this example, for each of n stars, information is included regarding coordinates indicating the position where the star should be drawn, a value indicating the brightness of the star, and the color of the star to be drawn. Additionally, information regarding a first delay time t1 and a second delay time t2 is included for each of the n stars. The first delay time t1 and the second delay time t2 are specified for each star, for example, from among several different values. Alternatively, instead of including independent delay time information in the light spot data, the delay time may be calculated by the projection control device 10 according to a predetermined rule based on the data number (e.g., 1 to n). In this case, the delay time information is essentially included in the data number. In this embodiment, the star is drawn in the first image from the time it crosses the boundary line until the specified first delay time t1. From the first delay time t1 to the second delay time t2, the star is drawn in both the first image and the second image, with the weight of brightness gradually shifting from the first image to the second image over time. After the second delay time t2 has elapsed, the star is drawn in the second image.

[0065] FIG. 8 is a diagram that schematically illustrates how a first star S1 and a second star S2 move together to the right near the overlap region 65, crossing the boundary line 76. As shown in this diagram, the stars indicated by circles move from left to right over time. Circles with the same symbol a, b, ..., z indicate the positions of the first star S1 and the second star S2 at the same time. Furthermore, white circles indicate stars drawn in the first image, black circles indicate stars drawn in the second image, and the brightness ratio of stars drawn in both the first and second images is indicated by the color depth.

[0066] In the example shown in FIG. 8, the first delay time t 11 and the second delay time t 21 and the first delay time t assigned to the second star S2. 12 and the second delay time t 22 The first delay time t of the second star S2 is different from 12 is the first delay time t of the first star S1 11 The second delay time t22 is the second delay time t of the first star S1 21 is longer than the first star S1. However, the time from the first delay time t1 to the second delay time t2 is longer for the first star S1. Therefore, the first star S1 is drawn in the first image from a to i, drawn in both the first and second images from i to n, with its brightness weight gradually shifting to the second image, and drawn in the second image from n to w. The second star S2 is drawn in the first image from a to q, drawn in both the first and second images from q to t, with its brightness weight gradually shifting to the second image, and drawn in the second image from t to z. In this way, the position and timing at which the drawn image switches from the first image to the second image differs for the first star S1 and the second star S2. As a result, the boundary line is less noticeable than when the images switch simultaneously when crossing the boundary line.

[0067] 9 is a flowchart showing an example of the operation of the projection control device 10 according to the third embodiment. Here, the process is shown for when each star moves from the first area 61 side of the first image to the second area 62 side of the second image. The operation of the projection control device 10 will be outlined with reference to this flowchart. The same applies when each star moves from the second area 62 side to the first area 61 side.

[0068] In step S301, the projection control device 10 acquires initial data and initializes various parameters, including the elapsed time t i The initial data also includes a status flag indicating the status of each star. Here, the status of each star can be a first state in which the star has not crossed the boundary line and is drawn in the first image, a second state in which the star has crossed the boundary line and is drawn in the second image after a second delay time t2 has elapsed, or a delayed state in which the star switches from the first state to the second state. The initial data includes information on the initial position of each star at the start of projection. As an initial value, the status flag is set to the first state when the initial position is closer to the first region 61 than the boundary line, and is set to the second state when the initial position is closer to the second region 62 than the boundary line.

[0069] In step S302, the projection control device 10 acquires light spot data indicating information about the star to be projected from the data providing device 30. In step S303, the projection control device 10 initializes various parameters when creating an image. For example, a variable i indicating the star number is set to 1, and the first image and the second image are initialized. In step S304, the projection control device 10 sets the star with star number i as the processing target and reads the data for star number i.

[0070] In step S305, the projection control device 10 determines the state of the star with star number i. When the state flag is in the second state, the state is determined to be the second state. When the state flag is in the delayed state, the state is determined to be the delayed state. When the state flag is neither in the second state nor the delayed state, it is determined whether the star with star number i has crossed the boundary line. When it has not crossed the boundary line, the state is determined to be the first state. When it has crossed the boundary line, the state flag is changed to the delayed state, and the elapsed time t i starts counting up, and it is determined that a delay state has occurred.

[0071] If it is determined in step S305 that the state is the first state, the process proceeds to step S306. In step S306, the projection control device 10 draws a star with star number i in the first image. Thereafter, the process proceeds to step S312.

[0072] If it is determined in step S305 that the state is the second state, the process proceeds to step S307. In step S307, the projection control device 10 draws a star with star number i in the second image. Thereafter, the process proceeds to step S312.

[0073] If the state is determined to be a delay state in step S305, the process proceeds to step S308. In step S308, the projection control device 10 determines the elapsed time t after the star with star number i crossed the boundary line. i is the first delay time t assigned to the star. 1i When the first delay time t 1iIf the time has not elapsed, the process proceeds to step S306, and the projection control device 10 draws a star with star number i in the first image.

[0074] In step S308, the elapsed time t i is the first delay time t 1i The second delay time t 2i When it is determined that the distance is less than the first delay time t 1i has elapsed but the second delay time t 2i If the time has not elapsed, the process proceeds to step S309.

[0075] In step S309, the projection control device 10 sets the first delay time t 1i to the second delay time t 2i The first delay time t 1i Based on the time that has passed since the start of projection, the projection control device 10 determines the respective brightness ratios at which the star is drawn in the first image and the second image. In step S310, the projection control device 10 draws the star in the first image and the second image based on the determined ratios. Thereafter, the process proceeds to step S312.

[0076] In step S308, the elapsed time t i is the second delay time t 2i When it is determined that the boundary line has been crossed, i.e., when the second delay time t 2i When the time has elapsed, the process proceeds to step S311. In step S311, the projection control device 10 changes the status flag to the second status. Thereafter, the process proceeds to step S307, where the projection control device 10 draws a star with star number i in the second image.

[0077] In step S312, the projection control device 10 adds 1 to the variable i indicating the star number. In step S313, the projection control device 10 determines whether the variable i is greater than the number n of stars included in the light spot data. If the variable i is not greater than the number n of stars, the process returns to step S304. In this way, n stars are rendered in the first image or the second image.

[0078] If the variable i is greater than the number n of stars, the process proceeds to step S314. In step S314, the projection control device 10 outputs the data of the created first image to the first projector 41, and outputs the data of the created second image to the second projector 42. The first projector 41, which has acquired the data of the first image, projects the first image onto the dome-shaped screen 50. The second projector 42, which has acquired the data of the second image, projects the second image onto the dome-shaped screen 50. The process then returns to step S302. By repeating the above operations, images representing stars are successively created based on the updated light spot data, and the images representing the stars are projected onto the dome-shaped screen 50.

[0079] In this embodiment, when each star moves from the first area 61 of the first image to the second area 62 of the second image, the position and timing at which the image displayed changes from the first image to the second image differs for each star. As a result, the boundary line becomes less noticeable compared to when the images change simultaneously when crossing the boundary line. In addition, the first delay time t 1i to the second delay time t 2i By appropriately shortening the time until the first image appears, the area in which the stars appear double is narrowed even if there is a discrepancy between the first and second images. In this way, the digital planetarium system 1 can project a starry sky that looks natural.

[0080] [Variations] First delay time t 1i and the second delay time t 2i The difference between the first delay time t and the second delay time t may be constant for each star. In other words, the time required to switch from drawing in the first image to drawing in the second image may be the same for all stars. 1i and the second delay time t 2i The first delay time t 1i Alternatively, when the time has elapsed, the image may be instantly switched from being drawn on the first video image to being drawn on the second video image.

[0081] Furthermore, since the appropriate delay time may differ depending on the width of the overlap region 65 and the movement time of the star, the delay time may be variable. For example, by multiplying the delay time recorded in the light spot data by a predetermined constant according to the movement speed of the star, the delay time may be lengthened when the star is moving slowly and shortened when the star is moving fast. Furthermore, when a star deviates from the overlap region 65 without waiting for the delay time, the first image may be switched to the second image before or at the moment of deviation.

[0082] Furthermore, in the third embodiment described above, one boundary line is used, but similar to the first and second embodiments, multiple boundary lines may be provided and one of the boundary lines may be specified for each star.

[0083] Also in the third embodiment, similarly to the second embodiment, the position of the boundary line may be changed depending on the direction of movement.

[0084] The present invention has been described above by showing preferred embodiments, but it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. [Explanation of symbols]

[0085] 1. Digital Planetarium System 10 Projection control device 12 Data Acquisition Section 14 Allocation decision unit 16 Image generation unit 18 Video output section 30 Data providing device 40 Projector 41 1st projector 42 Second Projector 50 Dome Screen 61 1st area 62 Second area 63 First Exclusive Area 64 Second Exclusive Zone 65 Overlapping area 71 1st boundary area 72 Second boundary area 73 Third boundary area 76 Borderline 77 Right Shift Boundary EL Left Edge ER Right Edge

Claims

1. A method for projecting a plurality of light points by projecting a light point cloud image in which the positions of the light points change over time from each of a plurality of projectors that are installed so as to have an overlapping area where the projection areas of the plurality of projectors overlap, comprising: acquiring light spot data including information regarding the position and brightness of each of a plurality of light spots; determining an allocation of which of the light point cloud images each of the projected light points should be included in, and when the position of the light point falls within the overlapping region, determining an allocation of which of the light point cloud images including the overlapping region each of the light points should be included in based on predetermined allocation conditions that are specified for each of the light points and are not all the same, and the allocation changes while the light point moves through the overlapping region, and determining an allocation in which an area of ​​a region in which one of the light points is included in multiple light point cloud images is equal to or greater than zero and smaller than the area of ​​the overlapping region; Drawing each of the projected light points in at least one of the light point cloud images based on the position, the brightness, and the allocation of each of the light points, and generating a plurality of light point cloud image data that is data of a plurality of the light point cloud images; projecting the light point cloud images from the respective projectors based on the light point cloud image data; Projection methods including:

2. The overlapping region includes a plurality of boundary regions, the allocation conditions include information on the boundary area designated for each of the light points, An allocation of which of the light points to include in which light point group image is determined based on a positional relationship between the position of the light point and the designated boundary area. The projection method according to claim 1 .

3. When the position of the light spot is within the designated boundary area, The light points are included in all of the light point cloud images including the boundary area, The luminance of the light point is distributed to a plurality of light point cloud images based on the position; the area of ​​the boundary region is greater than zero and smaller than the area of ​​the overlap region; The projection method according to claim 2 .

4. The projection method according to claim 2 , wherein the area of ​​the boundary region is zero.

5. 5. The projection method according to claim 2, wherein the position of the boundary area is corrected in accordance with the direction of movement of the light spot.

6. For a predetermined period after the positional relationship between the position of the light point and the designated boundary area satisfies a predetermined condition, the light point is included in any of the light point cloud images including the boundary area; The luminance of the light points is distributed to the plurality of light point group images based on the elapsed time after the predetermined condition is satisfied.

6. A projection method according to claim 2.

7. The overlapping region has a boundary line, the allocation conditions include information on a delay time after crossing the boundary line specified for each of the light points, When the specified delay time has elapsed since the position of the light point crossed the boundary line, the allocation of which light point group image the light point should be included in is changed. The projection method according to claim 1 .

8. a plurality of the boundary lines are provided in the overlapping region, The allocation conditions further include information of the boundary line specified for each of the light points, When the specified delay time has elapsed since the position of the light point crossed the specified boundary line, the allocation of which light point group image the light point should be included in is changed. The projection method according to claim 7.

9. For a predetermined period of time from when the specified delay time has elapsed since the position of the light point crossed the boundary line, the light point is included in any of the light point group images including the boundary line, The brightness of the light points is distributed to the plurality of light point group images based on the elapsed time after the specified delay time has elapsed.

9. The projection method according to claim 7 or 8.

10. 10. The projection method according to claim 7, wherein the position of the boundary line is corrected in accordance with the direction of movement of the light spot.

11. A projection control device comprising a processor that executes the projection method according to any one of claims 1 to 10.

12. The projection control device according to claim 11; the plurality of projectors; A digital planetarium system equipped with:

13. A program for causing a projection control device to execute the projection method according to any one of claims 1 to 10.

Images