Aerial image display system

Abstract

This invention provides an aerial image display device that utilizes the back projection method of image reconstruction to display aerial images in a mist / smoke space that are visible from any direction and appear aesthetically pleasing. [Solution] The video generation device 18 has n light-emitting units 18a that project light TK toward the center G of the video display unit 12a. The n light-emitting units 18a are arranged in order to surround the entire or a part of the area around the video display unit 12a, and the video display unit 12a is positioned inside a polygon formed by sequentially connecting the centers of the light sources. The projection light TK of each light-emitting unit 18a is controlled by projection data obtained by applying filter correction used in back projection to transmission intensity data when viewing the display object from multiple directions corresponding to the installation position of each light-emitting unit 18a. The video generation device 18 combines each projection light TK in the video display unit 12a and scatters it with mist MI to cause the Tyndall effect, thereby generating a visible aerial image KE.

Description

Technical Field

[0001] The present invention relates to an aerial video display system that displays a planar or three-dimensional aerial video representing a display object in a space where mist or smoke is generated.

Background Art

[0002] Conventionally, as disclosed in Patent Document 1 for example, a mist generation unit and an air flow generation unit cooperate to generate a substantially cylindrical mist space, a plurality of projectors are arranged so as to surround the mist space, and for each projector, an image control device creates and supplies projection data corresponding to the position of each projector, and based on the supplied projection data, each projector irradiates projection light to the space irradiation part of the mist space, and the light is scattered by Mie scattering to cause a Tyndall phenomenon, and there has been a stereoscopic video display system in which a stereoscopic video observable with the naked eye is displayed in the space irradiation part.

[0003] This stereoscopic video display system applies the technology used in X-ray CT. When videos from each projector are projected onto the space irradiation part, each video is synthesized in the space irradiation part (added at each point in the space irradiation part), and the same phenomenon as the back-projection method generated by numerical calculation, that is, a real image (that is, a stereoscopic image) corresponding to the original structure that created those projection images is generated in the space irradiation part.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The stereoscopic video display system of Patent Document 1 needs to generate a substantially cylindrical mist space using a dedicated air flow generation device, and due to the structure of the system, the space video can only be viewed from the side of the mist space.

[0006] Furthermore, Patent Document 1 states that the number of projectors to be placed around the mist space should be "for example, around 10 to 12 units," but it does not consider the relationship between the number of units and the quality of the displayed image. After diligent research by the inventors of this application, it was found that it is difficult to display aerial images with high quality and a good appearance using only around 10 to 12 units.

[0007] The present invention has been made in view of the above-mentioned background art, and aims to provide an aerial image display device that can display aerial images that are visible from any direction in a space where mist or smoke is generated, in an aesthetically pleasing manner, by utilizing the back projection method of image reconstruction techniques. [Means for solving the problem]

[0008] The present invention is an aerial image display system that displays a two-dimensional or three-dimensional aerial image representing an object to be displayed in a mist / smoke space where mist or smoke is generated. The system comprises a mist / smoke generating device that generates mist or smoke to create the mist / smoke space, and an image generating device that generates the aerial image on the image display unit within the mist / smoke space, wherein the image generating device has a plurality of light projectors that are installed around the image display unit and project light toward the center of the image display unit. Multiple light-emitting units are arranged sequentially along a virtual plane to enclose all or part of the area surrounding the image display unit, and the image display unit is positioned so that it fits inside a polygon formed by sequentially connecting the light source centers of each light-emitting unit. The projected light from each light-emitting unit is controlled by projection data obtained by applying filter correction used in back projection to transmission intensity data when viewing the display object from multiple directions corresponding to the installation position of each light-emitting unit. The aforementioned image generation device is an aerial image display system that generates an aerial image that can be viewed from any direction by combining the projected light from each of the light-emitting units in the image display unit and scattering it with the mist or smoke to produce a Tyndall effect.

[0009] Each of the light-emitting units is arranged such that the average angle between two imaginary lines connecting the light source center of two adjacent light-emitting units and the center of the image display unit is 7.2 degrees or less, and the positions of the two adjacent light-emitting units do not overlap.

[0010] For example, the structure to be displayed is an intangible 2DCG model or 3DCG model, and the projection data is calculated based on the transmission intensity data, which is an integral value in the direction corresponding to the installation position of each light-emitting unit, from the density distribution data of the object to be displayed defined in three-dimensional space.

[0011] The video display unit may be installed inside a building, and the multiple light-emitting units may be arranged in a ring shape along the virtual plane facing the ground, with the units installed around the video display unit. Alternatively, the video display unit may be installed inside a tunnel-shaped structure that covers the video display unit from above, and the multiple light-emitting units may be arranged on the upper and side surfaces inside the tunnel-shaped structure, along the virtual plane at an angle intersecting the ground. The aerial image may be a moving image. [Effects of the Invention]

[0012] The stereoscopic display video system of the present invention generates mist or smoke in any space to create a mist / smoke space, and displays an aerial image on a video display unit within the mist / smoke space. Since it can eliminate obstacles such as the airflow generating device of Patent Document 1, people inside the mist / smoke space or people around the mist / smoke space can view the aerial image from any direction. Furthermore, by installing a number of light-emitting units that meet predetermined conditions, the aerial image can be displayed with high resolution and in a good, visually appealing manner. [Brief explanation of the drawing]

[0013] [Figure 1]The first embodiment of the aerial image display system of the present invention is shown as a front view (a) installed inside a building, and the first embodiment is shown as a perspective view (b) of the image generation device installed on the ceiling, viewed from below. [Figure 2] This is a schematic diagram showing the arrangement of multiple light-emitting units in the aerial image display system of the first embodiment. [Figure 3] This is a schematic diagram illustrating how light rays emitted from multiple light-emitting units are combined. [Figure 4] Figures (a) and (b) show the simulation results verifying the relationship between the number of light-emitting units and the appearance of the aerial images when three types of aerial images are displayed using the aerial image display system of the first embodiment. [Figure 5] (a) is a schematic diagram showing a modified arrangement of multiple light-emitting units in the aerial image display system of the first embodiment, and (b) is a schematic diagram showing a comparative example of the arrangement of multiple light-emitting units. [Figure 6] (a) is a front view showing a second embodiment of the aerial image display system of the present invention installed inside a tunnel, and (b) is a schematic diagram showing the arrangement of multiple light-emitting units. [Modes for carrying out the invention]

[0014] <Aerial image display system 10 in the first embodiment> The first embodiment of the aerial image display system of the present invention will be described below with reference to Figures 1 to 6. The aerial image display system 10 of this embodiment is a system that displays a planar or three-dimensional aerial image KE representing an object to be displayed in a mist space 12, and is used by being installed in, for example, an event hall 14 inside a building, as shown in Figures 1(a) and (b).

[0015] The aerial image display system 10 includes a mist generator 16 and an image generator 18. The mist generator 16 is installed inside the event hall 14 and is a device that generates mist MI to turn the inside of the event hall 14 into a mist space 12. Note that the mist space 12 may be a smoke space in which smoke is generated. In that case, a smoke generator is installed instead of the mist generator.

[0016] The image generator 18 has a plurality of light projecting units 18a installed around the image display unit 12a and irradiating projection light TK toward the center G of the image display unit 12a. The plurality of light projecting units 18a are arranged in order along the lower surface of the flat ceiling 14a (the surface facing substantially parallel to the ground). As shown in FIG. 2, they are arranged in a ring so as to surround the entire area around the image display unit 12a, and the image display unit 12a is accommodated inside the surrounded area. The number of the light projecting units 18a is n, and here, they are arranged at equal intervals so as to draw a beautiful circle. Therefore, if two adjacent light projecting units 18a are denoted as light projecting units 18a(k - 1) and 18a(k), and the angle between two virtual lines connecting the light source centers of the light projecting units 18a(k - 1) and 18a(k) and the center G is denoted as θ(k), the angle θ(k) can be expressed as 360 / n degrees. The number n of the light projecting units 18a and the angle θ(k) are important indexes for displaying the aerial image KE beautifully, and will be described in detail later.

[0017] The projection light TK of each light projection unit 18a is formed based on unique projection data. The projection data is data obtained by applying filter correction used in the back-projection method to the transmission intensity data when the display object is viewed from a plurality of directions according to the installation position of each light projection unit 18a. The back-projection method is one of the image reconstruction methods widely used in fields such as X-ray CT (Computed Tomography), and it reconstructs a cross-sectional image of an object from the transmission intensity data of X-rays. The reconstructed image is based on the projection-slice theorem, which is known as the mathematical principle for image reconstruction in X-ray CT technology. The projection-slice theorem is a theorem stating that for any point on a cross-section, complete image reconstruction is possible when the light rays of the transmission intensity data passing through that point reach from all directions. Based on this, the aerial image KE is formed from the transmission intensity data by the back-projection method.

[0018] Furthermore, if the transmission intensity data is simply back-projected, the image will become blurred. Therefore, usually, a predetermined filter correction is applied and then back-projection is performed to suppress image blurring (filter correction back-projection method). In the aerial image display system 10, the projection data obtained by applying this filter correction is used.

[0019] Note that even when the basis of the display object is not a physical object but a 2D CG model or a 3D CG model (two-dimensional or three-dimensional computer graphics model), the projection data can be created in a similar way. In this case, the projection data can be calculated by calculating the transmission intensity data, which is the integral value in the direction corresponding to the installation position of each light projection unit 18a, from the CG model density distribution data defined in the three-dimensional space, and further applying the filter correction described above.

[0020] The video generation device 18 synthesizes the projection lights TK (light rays controlled by the projection data) of the n light projection units 18a on the video display unit 12a, scatters them with the mist MI to cause the Tyndall phenomenon, and thereby generates the aerial image KE so that it can be visually recognized from any direction.

[0021] The scattering of mist MI is mainly Mie scattering, and for Mie scattering to occur, the particle size of the mist MI must be 1 to several times the wavelength of the light. Therefore, in order for Mie scattering to occur over the entire visible light wavelength range, the particle size of the mist MI is preferably 0.5 μm to 10 μm.

[0022] Furthermore, in order to achieve good Mie scattering without multiple scattering occurring, the inter-particle distance needs to be about 5 to 10 times the particle diameter, so the particle density should be 2000 particles / cm³. 3 The following is recommended. However, in order to make the light rays visible even when the particle size is small (so that a few percent of the light rays are visible), the particle density should be 100 particles / cm³. 3 It is preferable to do as described above. Incidentally, in the case of Patent Document 1 shown in the background art, the particle density (mist concentration) is 1000 to 2000 particles / cm³. 3 Because this is necessary, the present invention can significantly reduce the particle density. The same applies to the particle size and particle density of mist MI when mist MI is replaced with smoke.

[0023] To briefly explain the principle by which the aerial image KE is generated on the image display unit 12a, for example, as shown in Figure 3, when the green light ray RL(G) emitted by the light-emitting unit 18a(k-1) and the red light ray RL(R) emitted by the light-emitting unit 18a(k) intersect at intersection point P(G+R), a yellow color, which is a combination of red and green, appears at the position of intersection point P(G+R). Also, when the green light ray RL(G) emitted by the light-emitting unit 18a(k-1) and the blue light ray RL(B) emitted by the light-emitting unit 18a(k) intersect at intersection point P(G+B), a cyan color, which is a combination of green and blue, appears at the position of intersection point P(G+B). Furthermore, when the red light ray RL(R) and the blue light ray RL(B) intersect, a magenta color, which is a combination of red and blue, appears at the position of intersection point P(R+B). Furthermore, in the parts of each ray that do not intersect with other rays, the color of the individual ray appears at that location. By performing image reconstruction based on this principle and the projection cross-section theorem described above, it is possible to display planar or three-dimensional color or monochrome images, and furthermore, still images and moving images can be freely displayed.

[0024] Next, the relationship between the number n and angle θ(k) of the light-emitting units 18a and the appearance of the aerial image KE will be explained. The inventors performed simulations assuming that n light-emitting units 18a are arranged in a ring at equal intervals around the entire 360 ​​degrees of the image display unit 12a, and verified how the appearance of the aerial image KE changes when the number of light-emitting units 18a is changed. When performing the simulations, the parameters were set assuming that the light-emitting units 18a were general-purpose scanning laser projectors (horizontal field of view 39 degrees, resolution 1280 x 720 pixels) and the aerial image KE was 480 x 480 pixels.

[0025] Figure 4(a) shows the simulation results of an aerial image KE(1) created based on video source 1 representing a two-dimensional logo mark based on the letter T of the alphabet, for an object to be displayed. In the case of such a simple logo mark, if the number of light-emitting units 18a n is 40 or less [angle θ(k) is 9.0 degrees or more], part or all of the logo mark becomes distorted and looks bad, but if it is 50 or more [angle θ(k) is 7.2 degrees or less], the overall appearance can be displayed well.

[0026] Figure 4(b) shows the simulation results of an aerial image KE(2) created based on video source 2, which represents a two-dimensional pattern consisting of two large circles in the center surrounded by seven smaller circles. In the case of this pattern, the large central circles could be displayed visually well when the number of light-emitting units 18a n was 50 or more [angle θ(k) 7.2 degrees or less], and the surrounding smaller circles could be displayed visually well when the number of light-emitting units 18a was 70 or more [angle θ(k) 5.1 degrees or less].

[0027] The simulation results in Figures 4(a) and 4(b) show that the number n of light-emitting units 18a and their angle θ(k) are important indicators for displaying the aerial image KE in a visually appealing manner. Furthermore, it was found that for simple display targets, setting the number n of light-emitting units 18a to an angle θ(k) of 7.2 degrees or less allows for a visually appealing display of the aerial image KE. In this case, it is also a condition that the positions of the light sources or optical axes of two adjacent light-emitting units 18a do not overlap. In addition, even if the n light-emitting units 18a are not or cannot be placed at equal intervals, a nearly identical effect can be obtained by ensuring that the average value of the angle θ(k) is 7.2 degrees or less.

[0028] As described above, the stereoscopic display video system 10 generates mist MI in the event hall 14 inside the building to create a mist space 12, and displays aerial images KE on the video display unit 12a within the mist space 12. This eliminates obstacles such as the airflow generating device described in Patent Document 1, so event participants can view the aerial images KE from any direction. Furthermore, by installing a large number of light-emitting units 18a so that the angle θ(k) is 7.2 degrees or less, the aerial images KE can be displayed with high resolution and in an appealing manner.

[0029] As shown in Figures 1(a) and 1(b), the above-mentioned aerial image display system 10 has n light-emitting units 18a installed on the ceiling 14a and the image display unit 12a positioned close to the ceiling 14a. Therefore, event attendees look up at the aerial image KE from an appropriate position below the image display unit 12a. For example, if the n projection units 18a are installed on the floor or at a height close to the floor, the image display unit 12a can be positioned close to the floor. In this case, event attendees can view the aerial image KE from an appropriate position above or to the side of the image display unit 12a.

[0030] Furthermore, in the case of the aerial image display system 10, as shown in Figure 2, n light-emitting units 18a are arranged in a ring to surround the entire area around the image display unit 12a. However, as shown in the modified example in Figure 5(a), they may be arranged to surround only a portion of the area around the image display unit 12a. In this case as well, the average value of the angle θ(k) related to each light-emitting unit 18a should be 7.2 degrees or less. A pair of light-emitting units 18a arranged in the diametrical direction with the center G in between will project almost the same projection light TK from opposite directions, so even if one of the projection light TKs is absent, the aerial image KE can be displayed with almost the same quality.

[0031] However, if only a portion of the area surrounding the video display unit 12a is enclosed, the video display unit 12a must be positioned so that it is entirely contained within the polygon formed by sequentially connecting the light source centers of each light-emitting unit 18a. For example, in the comparative example shown in Figure 5(b), only exactly half of the area surrounding the video display unit 12a is enclosed, and about half of the video display unit 12 extends beyond the straight line connecting the light source center of light-emitting unit 18a(1) and the light source center of light-emitting unit 18a(n). Therefore, the aerial image KE within the video display unit 12a cannot be displayed without defects.

[0032] The projection cross-section theorem states that for any point on the image display unit 12a, complete image reconstruction is possible if light rays of transmission intensity data passing through that point arrive from all directions. However, in the comparative example shown in Figure 5(b), the preconditions of this projection cross-section theorem no longer hold. For example, region α within the image display unit 12a is the part that extends the largest from the polygon connecting each light-emitting unit 18a, and region α does not receive enough light rays necessary for image reconstruction. In other words, the projection light TK(1) to Tk(N) alone cannot deliver enough light rays necessary for image reconstruction, resulting in insufficient information for image reconstruction, and defects appear in region α and its surroundings when the aerial image KE is displayed.

[0033] <Aerial image display system 20 of the second embodiment> Next, a second embodiment of the aerial image display system of the present invention will be described with reference to Figure 6. Here, components similar to those in the above embodiment are denoted by the same reference numerals and their description is omitted. The aerial image display system 20 of this embodiment is a system that displays a planar or three-dimensional aerial image KE representing an object to be displayed in a mist space 12, similar to the above embodiment, and is used by being installed inside a tunnel 22 that allows passage through the ground, such as in a mountainous area, as shown in Figure 6(a). The content of the aerial image KE could be, for example, road signs or warning displays that draw attention to drivers of automobiles or pedestrians traveling on the road 22a inside the tunnel 22.

[0034] The aerial image display system 20 includes a mist generator and an image generation device 18 (not shown). The mist generator generates mist MI inside the tunnel 22, creating a mist space 12 [a space where the density of mist MI is above a certain value] with a length of, for example, 3 to 10 m, at a location along the length of the tunnel 22.

[0035] The video generation device 18 has n light-emitting units 18a that are installed around the video display unit 12a and project light TK toward the center G of the video display unit 12a. In the case of the aerial video display system 20, the n light-emitting units 18a are installed on the upper and side surfaces inside the road tunnel 22, arranged sequentially along a virtual plane that is almost perpendicular to the ground, and are arranged in a roughly U-shape to enclose a portion of the area around the video display unit 12a, with the video display unit 12a housed inside this enclosed area.

[0036] The total number of light-emitting units 18a is n, and the number n is set such that the average value of the angle θ(k) is 7.2 degrees or less, and the positions of two adjacent light-emitting units 18a do not overlap. Furthermore, the projected light TK of each light-emitting unit 18a is controlled by projection data similar to that described above. Therefore, the aerial image display system 20 can also display the aerial image KE with high quality and a good appearance.

[0037] <Other embodiments, etc.> It should be noted that the aerial image display system of the present invention is not limited to the above embodiments. For example, in Figure 1(a), the mist generator 16 is installed inside the event hall 14, but it may also be installed outside the event hall 14 and the mist MI may be sent into the event hall 14. Also, in Figure 1(a), the entire interior of the event hall 14 is made into a mist space 12, but only a specific area inside the event hall 14 may be made into a mist space 12 [an area where the density of mist MI is higher than the surrounding area]. The same applies when the mist generator is replaced with a smoke generator.

[0038] The light-emitting section of the image generation device can use a widely used projector, but any light-emitting device other than a projector can be used as long as the desired effects of the present invention are achieved. For example, a light-emitting device that prints pre-calculated transmission intensity data onto a transparent plate and illuminates the image display section with white light from behind the plate may also be used. Furthermore, the layout when arranging the light-emitting sections can be freely changed to an annular shape as shown in Figure 2, a roughly semicircular shape as shown in Figure 5(a), or a roughly U-shape as shown in Figure 6(b), or a roughly elliptical or semi-elliptical shape. In addition, the angle between the virtual plane on which the multiple light-emitting sections are arranged and the ground can be appropriately changed according to the installation location and the application of the system.

[0039] The types and combinations of equipment that make up the video generation device are not particularly limited. For example, it may be configured by combining multiple independent light-emitting devices (light-emitting units) with a control computer, or, if the aerial image and video display unit are small, it may be configured by arranging multiple light-emitting lenses (light-emitting units) side by side on the side of a single integrated body.

[0040] The tunnel-like structure on which the aerial image display system of the present invention is installed is not limited to the tunnel 22 described above (a tunnel that allows passage through the ground, such as in mountains), but may also be other infrastructure structures, such as protective sheds installed on roads in mountainous areas. It may also be a tunnel-like passageway installed as a children's play area in an event hall inside a building. [Explanation of symbols]

[0041] 10,20 Aerial Image Display System 12. Mist Space (Mist / Smoke Space) 12a Video display unit 14 Event Hall 14a Ceiling 16. Mist Generator (Mist / Smoke Generator) 18. Video generation device 18a Light-emitting section 22. Tunnels (Tunnel-like structures) 22a road KE Aerial Images MI Mist TK projection light α region θ angle

Claims

1. An aerial image display system that displays a two-dimensional or three-dimensional aerial image representing an object to be displayed within a mist or smoke space, The system comprises a mist / smoke generating device that generates mist or smoke to create the mist / smoke space, and an image generating device that generates the aerial image on the image display unit within the mist / smoke space, wherein the image generating device has a plurality of light projectors that are installed around the image display unit and project light toward the center of the image display unit. Multiple light-emitting units are arranged sequentially along a virtual plane to enclose all or part of the area surrounding the image display unit, and the image display unit is positioned so that it fits inside a polygon formed by sequentially connecting the light source centers of each light-emitting unit. The projected light from each light-emitting unit is controlled by projection data obtained by applying filter correction used in back projection to transmission intensity data when viewing the display object from multiple directions corresponding to the installation position of each light-emitting unit. The aforementioned image generation device is characterized by generating an aerial image that can be viewed from any direction by combining the projected light from each of the light-emitting units in the image display unit and scattering it with the mist or smoke to cause a Tyndall effect.

2. The aerial image display system according to claim 1, wherein each of the light-emitting units is arranged such that the average value of the angle between two imaginary lines connecting the light source centers of two adjacent light-emitting units and the center of the image display unit is 7.2 degrees or less, and the positions of the two adjacent light-emitting units do not overlap.

3. The aerial image display system according to claim 1 or 2, wherein the structure to be displayed is an intangible 2D CG model or 3D CG model, and the projection data is calculated from density distribution data of the object to be displayed defined in three-dimensional space, based on the transmission intensity data which is an integral value in a direction corresponding to the installation position of each light-emitting unit.

4. The aerial image display system according to claim 1 or 2, wherein the image display unit is installed inside a building, and the plurality of light-emitting units are installed around the image display unit and arranged in a ring along the virtual plane facing the ground.

5. The aerial image display system according to claim 1 or 2, wherein the image display unit is provided within a tunnel-shaped structure that covers the image display unit from above, and the plurality of light-emitting units are arranged on the upper and side surfaces inside the tunnel-shaped structure along the virtual plane at an angle intersecting the ground.

6. The aerial image display system according to claim 1 or 2, wherein the aerial image is a video.

Images