JP5068007B2 - Video projection system - Google Patents

Description

  The present invention provides a video projector capable of projecting an image that can be arbitrarily moved on a dome screen in addition to an image of a constellation and the like so that the reference mark becomes a coordinate on a predetermined dome screen of the dome screen. The present invention relates to a video projection system that has reference mark means that can be displayed on the screen and has means for projecting an image projected by a video projector to a position to be originally projected.

In a conventional planetarium, an optical star projector that projects a star at the center of a dome screen is installed to project the star. An optical stellar projector can project a very sharp star image using multiple projection lenses and a stellar original plate with a precisely processed through-hole pattern, which can reproduce a very realistic and beautiful starry sky. did it.
Also, in conventional planetariums, video projectors have been used to project various astronomical objects other than stars and various images.

  For example, effects such as overlaying constellation pictures or constellation lines using a video projector on the starry sky projected by a stellar projector have been performed. Since the image generated by a video computer can be projected directly by a projection device such as a constellation picture, it is easy to change the content of the image, and the image can be moved and deformed in real time as needed, so conventional auxiliary projection It is now difficult to use the machine, and it has become possible to obtain complex and sophisticated effects such as moving the constellation through animation and linking it with a star.

However, the conventional technique has the following problems.
In order to synchronize the starry sky from the star projector and the image from the video projector, the positional relationship between the image from the star projector video projector and the star image projected from the star projector must be maintained accurately. Challenges arise. In other words, the video projector and the stellar projector are installed separately, and the projection lens is completely different, so the positional relationship of the images projected from both is complicated. After converting the position of the stellar image to coordinates on the dome screen, for example, horizon coordinates, the computer calculates the correspondence between the horizon coordinates and the coordinates on the projector screen by some method, and displays the figure based on this result. It is also necessary to project an image output by distorting the image into a necessary shape.

In order to create a function that creates the relationship between the horizon coordinates and the coordinates on the screen, the data on the correspondence between the coordinates on the screen and the horizon coordinates at a number of points in the image can be obtained in some way, or various projection-related data can be obtained. The calculation must be performed in consideration of various geometric parameters, that is, the installation position and orientation angle of the projector, and the aberration characteristics of the projector lens.
Recently, these calculations can be performed accurately in a very short time using a computer. However, it is very difficult to accurately match the installation position and attitude angle of the projector with the design values, and it is also very troublesome to measure the values where these are actually installed. Further, since there may be slight errors in the construction of the dome screen, these errors affect the projection position of the image, and it is difficult to accurately project only with the above calculated values.

Patent Documents 1 and 2 disclose an example of a conventional planetarium apparatus that projects a video image and an image such as a star on a dome by a video projector and a stellar projector.
Patent Document 1 introduces a celestial body coordinate input from a telescope console into the field of view of an astronomical telescope, shoots the field of view with a video camera, and projects it onto a dome screen with a video projector. It matches the projection position by the star projector. Further, Patent Document 2 is a system for projecting onto a planetarium dome with a video projector that projects video and a projector that projects stars, etc. The image of the camera fixed to the video projector is seen, and the locus is traced on the touch panel. By tracing, the trajectory is projected onto the dome. However, the above Patent Documents 1 and 2 do not disclose means for correcting distortion of the projected image by the video projector with respect to the image by the star projector, and more specifically about the alignment of the projected images of the video projector and the projector. There is no simple structure.
JP-A-5-88610 JP-A-7-181889

  From the above background, conventionally, for example, a reference mark such as an azimuth angle and altitude is projected by a laser projector or the like, or an LED or the like is installed on a dome screen, and a scale corresponding to the altitude and azimuth is projected from the projector. The process of checking and correcting the difference between the reference mark and the scale with the human eye was necessary. However, this requires labor and cost, and also requires skilled workers, which increases the installation cost of the video projector and the operating cost of the entire system. In addition, if the installation position of the projector deviates for some reason, or if the projector is replaced with a replacement device due to damage to the projector, the previous state will be completely removed due to limitations in installation work or differences in individual projectors. It is difficult to restore, and the adjustment work described above must be performed again, which may hinder stable operation of the video facility. In addition, video projectors have a shorter product update cycle than planetarium equipment, and if the projector being used is discontinued while operating the planetarium facility, it will be necessary to change to a new model number. Also, it was necessary to redo the adjustment work as described above.

The present invention has been made to solve the above problems.
The object of the present invention is to provide a stellar image projected from a stellar projector installed at or near the center of the screen, such as a dome shape, a projected image by a mark projector installed independently, or a mark installed on the screen. , Using mark means whose coordinates on the screen are known, project the image (cursor) to be displayed from the video projector so that it matches the reference mark, and the coordinates of the cursor on the screen at this time and the reference By using the on-screen coordinates of the mark, calculating the coordinate conversion parameters between the on-screen coordinates and the projected screen coordinates, or by performing an interpolation operation, it is possible to reduce the labor of installation adjustment and image misalignment correction work, and In order to accurately maintain the positional relationship with the stellar image projected from the stellar projector, images, videos, figures, etc. of the desired position and shape are corrected. It is to provide an image projection system capable of projecting a.

In order to achieve the above object, claim 1 of the present invention projects an image output from image generation means such as a computer or a video device onto a dome-shaped screen having a curved surface, and is arbitrarily moved on the screen. A projector capable of projecting an image as a possible landmark, a stellar projector that reproduces the starry sky on the dome-shaped screen, and the angular position control of the stellar projector, the coordinates on the screen are on the dome-shaped screen. Reference mark means for displaying a reference mark so as to be known, alignment means for aligning the reference image projected from the projector and the reference mark at a plurality of locations on the screen, and the alignment means in stores projected screen coordinates of the matched mark image and the coordinates on the dome-shaped screen of the reference mark, a screen Coordinates - storage means for storing the screen coordinate corresponding data, the on-screen coordinates - using the screen coordinates corresponding data, the coordinates of the projector corresponding to each screen on the coordinate, the coordinate transformation parameters of the focal length of the attitude angles or photographic lens Coordinate conversion parameter calculation means for calculating, and coordinate conversion means for performing coordinate conversion from coordinates on the screen to coordinates on the projection screen or from coordinates on the projection screen to coordinates on the screen using the coordinate conversion parameters, the stellar projection An image projected onto the dome-shaped screen of the projector corresponding to the starry sky projected by the machine is displayed with correction of displacement and shape on the dome-shaped screen.
According to a second aspect of the present invention, an image output from image generation means such as a computer or a video device is projected onto a dome-shaped screen having a curved surface, and an image that can be arbitrarily moved on the screen is formed. A projector capable of projecting, a stellar projector that reproduces the starry sky on the dome-shaped screen, and a reference so that the coordinates on the screen are known on the dome-shaped screen by the angular position control of the stellar projector. A reference mark means for displaying the mark, a mark image projected from the projector, a positioning means for aligning the reference mark at a plurality of positions on the screen, and an image corresponding to the mark matched by the positioning means Multiple coordinates on the projected screen and the coordinates on the dome-shaped screen of the reference mark are stored, and the coordinates on the screen correspond to the screen coordinates. Using the storage means for storing the data and the on-screen coordinate-screen coordinate correspondence data, the screen coordinates corresponding to each of the plurality of on-screen coordinates in the vicinity of an arbitrary position are obtained, and the interpolation calculation is performed on the plurality of screen coordinates. Interpolation calculation means for obtaining screen coordinates corresponding to the coordinates on the screen at an arbitrary position, and an image projected on the dome-shaped screen of the projector corresponding to the starry sky projected by the stellar projector, The shift and shape on the dome-shaped screen are corrected and displayed.
According to a third aspect of the present invention, in the invention according to the first or second aspect, the positioning means includes a camera that captures the image that serves as the mark and the reference mark, and an image that serves as the landmark from the captured image of the camera and a reference. A mark is extracted, a difference between an image position serving as a mark and a reference mark position is detected, and an image position serving as a mark output from the projector is controlled so that the image position serving as the mark matches the reference mark position. And a control means.
According to a fourth aspect of the present invention, in the invention according to the third aspect, the camera is mounted on the reference mark means.
According to a fifth aspect of the present invention, in the first or second aspect of the invention, the positioning means includes an operation device that can manually move the image to be the mark in the projection screen, and the mark is made by the operation device. The image is aligned with the reference mark.
Claim 6 of the present invention, the reference mark of the reference mark means in the invention of claim 1, 2, 3, 4 or 5, wherein is characterized by using the image of stars projected from star projector .
According to a seventh aspect of the present invention, in the invention according to the first, second, third, fourth or fifth aspect, the reference mark means is controlled so as to be projected onto a predetermined coordinate on the dome-shaped screen. It is a projection device.
According to an eighth aspect of the present invention, in the first, second, third, fourth or fifth aspect, the reference mark means is a projection device mounted on a stellar projector.
According to a ninth aspect of the present invention, in the invention according to the eighth aspect, the projection device sets the coordinates of the reference mark on the dome-shaped screen by controlling the angular position of the rotation axis of the stellar projector. .
According to a tenth aspect of the present invention, in the invention according to the first , second , third , fourth , fifth , seventh , eighth, or ninth aspect, the image and the reference mark as the mark can be arbitrarily turned on and off.
According to an eleventh aspect of the present invention, in the invention according to the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, or tenth aspect, the coordinates on the dome-shaped screen of the reference mark are expressed by altitude and azimuth. It is characterized by being a horizontal coordinate.

  According to the above configuration, it is possible to easily and accurately correct the deviation of the projected image of the video projector with respect to the projected image of a star or the like projected onto the dome screen. Simplification of installation work and cost reduction can be achieved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, the relationship between the coordinates on the projection screen and the coordinates on the hemispherical dome screen when a video projector is installed in the planetarium dome facility will be described.
The video projector projects the video (projection screen) output from the video generation device almost as it is. If the screen is a plane and is orthogonal to the optical axis of the video projector, the projected screen is projected on the screen surface as it is.
However, in the case of a dome screen, since the screen surface is a curved surface, a complicated distortion occurs in the projected image. Therefore, it is necessary to distinguish the coordinates on the projection screen from the coordinates on the dome screen.

1A to 1F are diagrams for explaining the relationship between the coordinates on the dome screen and the coordinates on the projection screen. Here, the coordinates on the dome screen are horizon coordinates expressed by altitude and azimuth with respect to the center of the dome.
FIG. 1A is a diagram showing horizon coordinates on a dome screen.
FIG. 1B shows a projection screen projected by this video projector. The coordinates on the projection screen are represented by two-dimensional orthogonal coordinates represented by X and Y. The width is W and the height is H.
FIG. 1C is a perspective view showing a state in which the projection screen shown in FIG. 1B is projected by a video projector installed in the dome screen. The video projector 3 projects an image 6 on the dome screen 1. A coordinate line 6a on the image 6 is a coordinate line on the projection screen indicated by a broken line in FIG. 1B.
FIG. 1D is an example of a projection screen for correctly projecting the horizon coordinate line on the dome. Since it is projected onto the spherical surface, complicated distortion occurs, and it can be seen that the horizon coordinate line draws a complex curve on the screen.

For example, when the orientation of the projector is shifted twice, the image example shown in FIG. 1E is obtained. If attention is paid to the vicinity of the zenith in the image example of the correct setting, it can be seen that the image near the zenith is slightly shifted downward. Furthermore, when the focal length of the lens is shortened, the image example shown in FIG. 1F is obtained. It can be seen that the degree of curving of the video differs when compared with a video example with the correct setting. In other words, the shape is a deformed shape from the original image shape.
In the present invention, the position and orientation of the video projector is obtained and the coordinates on the dome screen are converted from the coordinates on the screen so as to minimize the above-mentioned image distortion, and the image or figure is projected to the correct position. Is.

First, before describing the embodiment of the present invention, the specific calculation content of the basic coordinate transformation of the projector will be described.
Here, it is calculated which coordinate on the projection screen of the projector corresponds to a known point of altitude and direction on the dome screen.
Cartesian coordinates with the origin of the dome as the origin, the X axis as the south, the Y axis as the west, the world coordinate as the Cartesian coordinate system with the Z axis as the zenith, and the projector position (lens aperture position) as the origin and the coordinate axis direction as the world coordinate An orthogonal coordinate system in which the system is a local coordinate, the projector position is an origin, the front is X, the side is Y, and the upper is Z with respect to the bottom of the projector is a projection coordinate.

Let f be the focal length of the projection lens of the projector, and R be the dome radius.
The pointer is projected onto the horizontal coordinate (AZM, ALT) (azimuth = AZM, altitude = ALT) by the servo control of the star projector.
Display the cursor so that it overlaps. The coordinates of the cursor on the projector screen at this time are (CX, CY).
Now, the actual values of the projector settings (position and attitude angle) are unknown, but this value is the world coordinate, for example, (PX, PY, PZ) as the design value, and the attitude angle (p, y, Assume r).
The world coordinates of the projected cursor image are
WX = R ・ cosAZM ・ cosALT
WY = R ・ sinAZM ・ cosALT
WZ = R ・ sinALT
It becomes. Convert this to local coordinates,
LX = WX-PX
LY = WY-PY
LZ = WZ-PZ
It becomes.

プロジェクタのパネル（画面）上の推定座標は
CPX ＝PYR/PXR
CPY ＝PZR/PXR
となる。
この計算例では、地平座標から投影画面上座標への変換例を示したが、もちろん逆の計算で、投影画面上座標から地平座標への変換も可能である。 To convert this to projection coordinates

The estimated coordinates on the projector panel (screen) are
CPX = PYR / PXR
CPY = PZR / PXR
It becomes.
In this calculation example, an example of conversion from the horizontal coordinate to the coordinate on the projection screen is shown, but it is of course possible to convert from the coordinate on the projection screen to the horizontal coordinate by reverse calculation.

FIG. 2 is a side view of a dome theater equipped with a video projection system according to the present invention, and FIG. 3 is a diagram for explaining an embodiment of a stellar projector used in the video projection system according to the present invention.
A stellar projector 2 having a number of projection units for projecting a star on the dome screen 1 has three rotation axes, a diurnal axis 2a, a latitudinal axis 2b, and an azimuth axis 2c. Any angular position can be set. By a driving source pedestal 12 (not shown) for receiving the support frame 11 and support frame 11 for supporting the fixed star projector 2, its Re respectively diurnal axis 2a, it can be adjusted latitude shaft 2b and azimuthal axis 2c, the computer 7 It is driven by the command.
A laser pointer 10 is installed as a reference marker projector on the latitude axis base of the stellar projector 2, and this laser pointer 10 can be arbitrarily turned on / off by a command from the computer 7.

When the light emitted from the laser pointer 10 hits the dome screen 1, a dot-like image is formed. The position of this point image is determined by the angle between the diurnal axis 2 a and the azimuth axis 2 c of the stellar projector 2. An arbitrary position on the screen 1 can be set. The center of the star projector 2 coincides with the spherical core of the dome screen 1, and the optical axis of the laser pointer 10 accurately intersects the diurnal axis 2a, the latitude axis 2b, and the azimuth axis 2c of the star projector 2, and the latitude If the plane 2b and the diurnal axis 2a are exactly perpendicular to each other, the azimuth angle and altitude of this point image are equal to the azimuth angle indicated by the azimuth axis 2c and the latitude angle indicated by the latitude axis 2b, respectively. .
Thereby, the stellar projector 2 has a function of projecting a point image of a laser beam at an arbitrary altitude and azimuth position on the dome screen 1 by controlling the angular positions of the latitude axis 2b and the azimuth axis 2c. It will be.
FIG. 5 shows an example of the position of the point image by the laser pointer.

The video projector 3 is configured to project a screen generated from the computer 7, and the content of the screen is projected onto the dome screen 1 as a video a. The attitude angle of this video projector is represented by the angle of each axis of pitch (p), yaw (y), and roll (r) as shown in FIG. 4, and the coordinates of the position of the video projector are represented by X as shown in FIG. , Y, and Z points (Px, Py, Pz).
The computer 7 controls display of a cursor that can be moved to an arbitrary position by an operation of a mouse or the like by an operator, and the cursor image 4 is projected onto the dome screen 1.

  When the azimuth axis 2c and the latitudinal axis 2b of the stellar projector 2 are set to certain predetermined values, the laser image is naturally projected to the predetermined value of azimuth and altitude (represented as AZM and ALT). When the position is within the range of the image a, the operator moves the cursor by operating the mouse or the like so that the cursor image projected by the video projector 3 matches the laser image projected from the stellar projector 2. The coordinates of the cursor at this time are recorded as data on the computer 7, and the coordinates are X and Y.

The operator manually inputs the altitude and direction of the known laser image, or obtains the altitude and direction directly from the stellar projector 2 using appropriate communication means and control means, and the value of the mouse cursor at that time is obtained. By obtaining the relationship between, for example, the X1, Y1 coordinate values on the projection screen (the screen projected by the projector) and the azimuth angle and altitude value on the actual dome, (X1, Y1) & (AZM1, ALT1) Get it in the form of The computer 7 can store this value. Hereinafter, the pair of (X1, Y1) and (AZM1, ALT1) is referred to as a horizon & screen coordinate pair.
This operation is repeated many times by changing the azimuth angle and latitude angle of the stellar projector, thereby creating a set of horizon & screen coordinate pairs of the relationship (Xn, Yn) & (AZMn, ALTn) (n = 1, 2, ...).

By creating this relationship over a wide range of screens, the relationship between the actual altitude and azimuth on the computer screen can be illustrated, and by complementing this value, on the screen for any altitude and azimuth. It is possible to create a complementary expression for obtaining an approximate expression of the coordinates of.
Therefore, for example, when it is desired to project a celestial object at an azimuth angle and altitude of (Azmp, Altp), the altitude and azimuth are converted into (Xp, Yp) of the XY coordinates based on this complementary formula, and the celestial object is located at this XY coordinate position Can project a celestial image at a desired azimuth and altitude position. The accuracy of the projection position becomes more accurate as the number of related data on the screen is larger and the interval is closer.
Since data sampling is time consuming, in order to obtain a better correction result with the minimum number of data samples, the projector position, orientation angle, and optical characteristics are not simply complemented with coordinate values. Thus, the method of converting the azimuth angle on the dome screen from the screen to the high altitude is close to the theoretical value and is preferable.
Therefore, the actual position and orientation angle of the projector, the optical characteristics of the projector, and the like are estimated using the sample values, and coordinate conversion is performed based on these values. This is a very good coordinate transformation.

The example of FIG. 3A shows an example in which the laser pointer 10 is incorporated in the stellar projector 2 as a reference mark means, but the laser pointer 15 is attached to the stellar projector 17 as shown in FIG. It can also be attached to the outer surface. Further, as shown in FIG. 3C, a reference marker such as a laser pointer 16 can be installed in the dome independently of the star projector 17, and a star image projected from the star projector is used as a reference mark. You can also.
The reference mark means of the type incorporated in the star projector 2 or attached to the outer surface knows the position of the projected reference mark by controlling the angular position of the azimuth axis and the latitude axis of the star projector 2 as described above. be able to. The reference mark means of the type installed independently has an adjustment mechanism for the angular position of its own azimuth axis and latitude axis, and the azimuth angle and altitude of the reference mark projected by this adjustment mechanism can be known. When using a star image, since the altitude azimuth angle on the projection screen at a predetermined date and time is known, this can be used to know the azimuth angle and altitude onto which the star image is projected.
Instead of projecting the reference mark, it is also possible to provide a plurality of azimuth angles on the dome screen, such as LEDs, light bulbs, phosphorescents, and fluorescent seals, and use these as reference marks.

FIG. 7 is a block diagram showing an embodiment of an apparatus for aligning a cursor and a pointer in a video projection system according to the present invention, and shows a configuration of a part of a computer for manually performing cursor alignment.
The horizon coordinate setting device 35 sets a predetermined azimuth angle and altitude (azm, alt) for the laser pointer. For example, a plurality of azimuth angles and altitudes are set in advance. It is output to the servo control device 36 and stored in the horizon coordinate one-screen coordinate correspondence data storage device 39. The timing at which this data is output from the servo control device 36 is automatically performed by detecting that the cursor image 34 has been aligned with the azimuth and altitude pointer image output immediately before, even if it is manually performed. You may go to The servo control device 36 includes a transmission mechanism (such as a reduction gear group, a drive shaft conversion gear, and a belt) that transmits the rotational driving force of a driving unit such as a motor to the azimuth axis and the latitude axis of the star projector 37 with a built-in pointer. The azimuth and latitude axes of the stellar projector 37 can be driven and adjusted so that the azimuth and altitude given from the horizon coordinate setting device 35 are the same. The pointer image 38 of the dome screen 40 is projected at a set azimuth angle and altitude of the star projector 37.

The cursor coordinate setting device 31 is a device for setting the coordinates of the cursor. The cursor can be moved to a predetermined position on the screen by operating the cursor position operating device 30 such as a mouse. The cursor coordinate setting device 31 recognizes the moved cursor position and displays the coordinate position of the cursor on the cursor display device 32 such as a liquid crystal display unit. A cursor is projected onto the dome screen 40 by the video projector 33, and the position thereof is the coordinate position displayed on the cursor display device 32. The cursor coordinates are associated with the horizon coordinates (azmn, altn) of the aligned pointer image and stored in the horizon coordinate one screen coordinate correspondence data storage device 39. As a result, the operator can store the position of the pointer image projected from the stellar projector whose azimuth and altitude are changed in order by aligning the cursor with the pointer.
Note that the cursor can be positioned by operating a direction key such as a keyboard or a cross key such as a pad instead of a mouse.

  In this way, the projector parameters (coordinates, posture angle, lens focal length) for realizing the minimum image distortion can be obtained by the parameter calculation device 40 using the data stored in the horizontal coordinate one-screen coordinate correspondence data storage device 39. The projector parameters obtained as described above are expressed as true projector parameters.

FIG. 8 is a block diagram showing another embodiment of the cursor and pointer alignment apparatus of the video projection system according to the present invention, and shows an example in which the cursor image is automatically aligned with the pointer image using a camera. ing.
The cursor display device 32, the video projector 33, the horizon coordinate setting device 35, the servo control device 36, the stellar projector 37, and the parameter calculation device 40 are the same as the devices given the same reference numerals in FIG.
The cursor coordinate setting device 53 is a device for setting the coordinates of the cursor, and a pointer image 61 and a cursor image 56 with respect to the cursor coordinates output to the video projector 33 based on error data input from the differential calculator 52. Control to output the cursor coordinates so that there is no error in the position of. The cursor coordinates output from the cursor coordinate setting device 53 are displayed on the cursor display device 32. A cursor is projected onto the dome screen 63 by the video projector 33, and the position thereof is the coordinate position displayed on the cursor display device 32.

  The video camera 57 captures the cursor image 56 and the pointer image 61 projected on the dome screen 63, and the analog image is converted into a predetermined image data format (image data) by the video capture unit 50. The image processing device 51 analyzes the input image data, recognizes the cursor image 56 and the pointer image 61 based on the feature shape, obtains the respective address data, and uses these address data to determine the XY coordinates of the cursor and the pointer. calculate.

  At this time, various methods for recognizing the cursor image and the pointer image are conceivable. For example, the pointer can be turned on / off, and the image is recorded with the pointer turned on (image A). Subsequently, if an image (image B) taken with the pointer turned off is prepared, and an image (image C) in which the brightness of each pixel is taken between the two images is created, image C can be used in an extra manner. The subject is canceled out and disappears, and only the pointer image portion emerges, so that the pointer image can be easily recognized. Similarly, the cursor can be similarly recognized by turning the cursor ON / OFF according to a command from the computer. The XY coordinate data of the cursor and the XY coordinate data of the pointer obtained by recognizing in this way are input to the-and + input terminals of the differential calculator 52, and error data is output from the differential calculator 52, and the cursor Input to the coordinate setting device 53.

If there is no error and the output of the differential calculator 52 is zero, the cursor coordinate setting device 53 stores the cursor coordinates in the horizontal coordinate one-screen coordinate correspondence data storage device 62, assuming that the cursor matches the pointer image. . The horizontal coordinate one-screen coordinate correspondence data storage device 62 stores the cursor coordinates in association with the horizontal coordinate (azmn, altn) of the pointer image that has been aligned.
If there is an error, the cursor coordinates corrected for the error are output from the cursor coordinate setting device 53, and an image similar to the above is taken in and calculated to perform alignment control of the cursor image and the pointer image. .

FIG. 14 is a schematic diagram showing an embodiment of the video projection system of FIG.
The camera 57 is juxtaposed to the stellar projector 37 having the laser pointer 41 and takes a pointer image and a cursor image projected on the dome screen, and the output is connected to a computer (not shown) and projected by a video projector. The coordinate position of the cursor image is automatically adjusted so that the cursor image matches the pointer image.

FIG. 15 is a perspective view showing an embodiment of a video projector installation structure.
The pedestal 58 is configured to be rotatable about the vertical direction. The vertical axis is a yaw (y) axis, and the yaw angle can be adjusted. A support column 59 is planted on the upper surface of the pedestal 58, and a support rod 60 is attached to the tip end of the support column 59 so as to be rotatable about the horizontal direction. This horizontal axis is the pitch (p) axis, and the pitch angle can be adjusted. A support frame 63 is attached to the upper end of the support rod 60 so that the video projector 33 can rotate around an axis parallel to the optical axis direction of the video projector 33. The axis parallel to the optical axis direction is the roll (r) axis, and the roll angle can be adjusted.
The attitude angle of the video projector can be adjusted by adjusting the yaw angle, pitch angle and roll angle. By setting the true projector coordinates and attitude angles determined by the parameter calculation device, it is possible to project an image from a projector with the least image distortion on an individual planetarium dome screen.

Subsequently, an embodiment in which coordinate conversion parameters are calculated using a reference mark and a cursor and coordinate conversion will be described.
On the premise that the curvature radius of the dome and the focal length of the projection lens of the video projector are known in advance, the video projector is mounted at a position and posture close to the designed position and posture, for example, and the screen is projected onto the dome screen. This combination of projector position and attitude angle is hereinafter referred to as a projector parameter.

Point the laser pointer at the specified azimuth and altitude (azm1, alt1). Then, the cursor on the projector screen is matched with the point image of the laser pointer. The point at this time is point 1, and the cursor coordinates (CX1, CY1) and (azm1, alt1) on the screen are collectively called a horizon & screen coordinate pair and stored in the computer. If this operation is repeated n times to the point n,
(CX1, CY1) & (azm1, alt1)
(CX2, CY2) & (azm2, alt2)
:
:
(Cxn, CYn) & (azmn, altn)
A data string of the horizon & screen coordinate pair is stored in the storage device 39 (62) of the computer.

Assuming that the projector position (x, y, z) and attitude angle (p, y, r) are certain values (for example, design values) (provisional projector parameters), the horizontal coordinates (azm1, alt1) Calculate where the points correspond on the projector screen. Let the calculated value be (CPX1, CPY1). This value is assumed to be an estimated coordinate on the projection screen.
Here, if the temporary projector parameters completely match the actual projector installation position and attitude angle, the estimated coordinates (CPX1, CPY1) are the coordinates on the screen (CX1, CPY1) extracted from the horizon & screen coordinate pair. Should match CY1). However, if there is an actual error, a difference due to the error occurs in both coordinates. The coordinate value error Err is
Err = ((CPX1−CX1) ² + (CPY1−CY1) ² ) ^1/2 (1)
become.

This is performed at a plurality of points, and the same calculation is performed on a plurality of horizon & screen coordinate pairs to obtain a sum ΣErr of each coordinate value error. If the temporary projector parameter matches the actual set value, ΣErr is still 0, but in reality, it becomes a value corresponding to the error.
FIG. 9 shows an embodiment of an error sum calculation apparatus for obtaining ΣErr.
In FIG. 9, the error sum calculation device is composed of coordinate conversion devices (1) 65a to (n) 65n, screen coordinate error calculation devices (1) 66a to (n) 66n, and an accumulation device 67.
Coordinate converters (1) 65a to (n) 65n take projector parameters for the horizontal coordinates (azm1, alt1) to (azmn, altn) and convert them into estimated coordinates (CPX1, CPY1) to (CPXn, CPYn), respectively. To do. The screen coordinate error calculation devices (1) 66a to (n) 66n incorporate estimated coordinates (CPX1, CPY1) to (CPXn, CPYn) with respect to the on-screen coordinates (CX1, CY1) to (CXn, CYn) (1 ) To calculate the coordinate value errors Err1 to n. The integrating device 67 integrates the coordinate value errors Err1 to n and outputs the sum of errors.

Therefore, conversely, if a projector parameter in which ΣErr is 0 can be found, it can be said that this is a true set value. Actually, there are measurement errors and the like, so there are very few conditions for ΣErr to be completely zero. However, it is only necessary to find a projector parameter (optimum projector parameter) where ΣErr is closest to zero.
There are various methods for determining the optimum projector parameter. For example, the simplest method is to search for a condition for obtaining the minimum value by obtaining ΣErr by changing the projector parameter in various ways with a value close to the design value. is there.
Projector parameters that ultimately use this position and attitude angle are adopted as coordinate transformation parameters, and the projector coordinate transformation is performed, and if the coordinates on the projector are calculated from the altitude and azimuth to be displayed, the image is always in the correct position. Can be displayed.

Next, a procedure for projecting the master image drawn on the basis of the horizontal coordinate using the coordinate transformation parameters so as to be correctly projected by the coordinate transformation will be described.
Here, in order to explain the master image, an example of the master image is shown in FIG.
The master image is a digital image composed of a predetermined number of pixels in the vertical and horizontal directions, and is stored in a master image memory (not shown) in the computer. As shown in the figure, the horizontal axis corresponds to the azimuth angle in the horizontal coordinate and the vertical axis corresponds to the altitude. The horizontal width is w pixels, the height is h pixels, and the resolution of an image for setting an angle corresponding to one pixel is RESO pixel / degree. In other words, for example, the horizontal coordinate (azmg, altg) of a pixel (gx, gy) in the image is
azmg = gx * RESO
altg = gy * RESO
It becomes.
From the master image memory, color information of a pixel at an arbitrary position can be extracted.

FIG. 11 is a flowchart showing a procedure for transforming the master image and drawing it on the projection screen.
When the program starts (step (hereinafter referred to as “S”) 01), the program performs processing on all pixels on the screen, so the coordinates GX on the master screen are changed from 0 to W, and GY is changed from 0 to H. Until one is changed. The execution of this loop operation is S02 and S03.
Then, the color information of each pixel set in the loop is read and substituted into the variable Col (S04). Further, the horizontal coordinate of this pixel is calculated from the coordinates GX and GY on the master screen and substituted for the azimuth angle azmg and the altitude altg (S05). The azmg and altg are converted into the coordinates on the screen of the projector by the coordinate conversion means, and these are set as CX and CY (S06). Subsequently, the point of the color acquired in S04 is drawn at the point of coordinates CX, CY on the projector screen (S07). By performing this for all pixels, an image for projecting the image at the correct position on the dome screen appears on the projector screen. S08 and S09 are the end of the loop of GX and GY.

FIG. 12 shows how the master image is deformed and projected correctly by such a procedure. FIG. 12A is a master image, and the coordinate lines are horizon coordinates (azimuth, altitude). FIG. 12B shows a state in which the master image is coordinate-transformed and drawn on the projection screen. For easy understanding, FIG. 12 shows coordinate lines that are not actually projected onto the dome screen. FIG. 12C is a perspective view of the projection screen projected by the projector. You can see how it is projected correctly along the horizontal coordinate scale on the dome.
In this embodiment, an example of drawing by converting to coordinates on the projector screen based on the coordinates of the original image is shown, but in actuality, the values of CX and CY are changed on the coordinates on the projector screen. And reverse conversion processing to convert from the XY coordinates to the horizon coordinates, find the coordinates GX, GY in the original image, and then read out the pixel color of the coordinates (GX, GY) of the original image on the screen Of course, it is possible to draw at the coordinates (CX, CY).

Next, a procedure for projecting a figure onto the dome screen by this coordinate conversion procedure will be described.
This embodiment is an example of drawing a line segment as an example of the simplest graphic. Drawing a line segment is a technique that is useful, for example, when connecting stars constituting a constellation with straight lines.
The feature points of the line segment are end points at both ends. These are designated as line segment end point 1 and line segment end point 2.
Each horizon coordinate is as follows.
The equator coordinates of line end point 1 are (AZM1, ALT1)
The equator coordinate of line segment end point 2 is (AZM2, ALT2).
This value is stored in the line segment data memory.

When the program starts, data is first read from the line segment data memory. Subsequently, the coordinates of the line segment end point 1 and the line segment end point 2 are converted by the coordinate conversion means to obtain screen coordinates (CX1, CY1)-(CX2, CY2). After that, if a line connecting (CX1, CY1) and (CX2, CY2) is drawn on the projector screen, a line connecting horizon coordinates (AZM1, ALT1) and horizon coordinates (AZM2, ALT2) will be displayed on the dome screen. Will be drawn.
FIG. 13 shows how line segments are correctly projected by executing the above program.
FIG. 13A illustrates the data of the line segments (line segment end point 1 and line segment end point 2) stored in the line segment data memory in an easy-to-understand manner. Such an image is actually prepared. Do not mean. FIG. 13B shows a state in which the coordinates of the line segment end point 1 and the coordinates of the line segment end point 2 are converted into coordinates on the projection screen by coordinate conversion and drawn on the projection screen. FIG. 13C is a perspective view of the projection screen projected by the projector. It can be seen that the line segments are correctly projected along the horizontal coordinate scale on the dome.

  By applying line segment drawing in this way, polygons such as triangles and quadrilaterals, and even complex figures can be drawn. Also, the coordinates of the feature points that make up the figure can be defined not only by horizon coordinates, but also by equator coordinates and zodiacal coordinates, which can be converted to horizon coordinates by coordinate transformation. If the coordinates of the star defined by the zodiac coordinates are used as feature points, it is possible to draw a point connecting the star and the star and draw a constellation line to show the constellation in an easy-to-understand manner.

Next, instead of using the parameter calculation apparatus shown in FIGS. 7 and 8 as means for correcting image distortion, an example using an interpolation method will be described.
Using a stellar projector as shown in FIG. 3, the horizon altitude and azimuth angle are set to a certain value and projected. Then, using the system of FIG. 7 or FIG. 8, coordinates (X, Y) on the computer screen are acquired by matching the position of the cursor. In addition, a device capable of performing calculation by the interpolation method is connected instead of the parameter calculation device 40 connected to the storage device 39 (62). The acquired data includes the horizontal coordinate (X, Y) of the cursor projected on the computer screen corresponding to this pointer, and the horizontal coordinate (X, Y) of the cursor projected in accordance with this pointer. Is stored in the storage device 39 (62).

If this operation is repeated by changing the azimuth angle and altitude of the pointer in steps of a fixed angle (for example, by 10 degrees), it is possible to obtain a set of horizon coordinate data corresponding to one screen coordinate. Of these, the screen coordinates are collectively displayed on the computer screen as shown in FIG. 16 (horizontal coordinates (azimuth angle, altitude) are shown together to aid understanding). Further, FIG. 17 shows that these points are connected by a straight line.
Here, for example, when you want to project some image on the dome at an azimuth angle of 10 degrees and an altitude of 10 degrees, from the data corresponding to the horizontal coordinates of one screen coordinate acquired here, the azimuth is 10 degrees and the altitude is 10 degrees. It is only necessary to select screen coordinates corresponding to the data and display the screen coordinates. However, in this case, it is not possible to set the altitude and azimuth of the image to be displayed in this case only with a jump value of 10 degrees. However, as can be easily guessed by looking at FIGS. 16 and 17, even if this value is in the middle, it is easy to interpolate from neighboring values, and the azimuth and altitude to be displayed are halfway values. Even if it exists, the screen coordinate corresponding to this can be calculated | required by interpolation calculation.

An error always occurs in the interpolation calculation. However, if the interpolation algorithm is a curve rather than a straight line, for example, a quadratic or cubic equation, or the interval between the obtained horizontal coordinate and one-screen coordinate correspondence data is made finer, sufficient accuracy is obtained. Can be raised.
Here, an embodiment in which an image having a certain area is displayed using this interpolation method will be described. When the angle, position, rotation angle, etc. for displaying the original image to be displayed are determined, the horizon coordinates corresponding to each pixel of this image can be obtained. The horizontal coordinates are obtained for each pixel, the coordinates on the screen are obtained from the horizontal coordinates by the above method, and the pixels are drawn there. If this is repeated, the image is displayed at the correct position on the dome screen.

Next, the complement method will be described.
By changing the azimuth and altitude in a constant step (the azimuth step value is dazm and the angle step value is dalt), the horizontal coordinate one-screen coordinate correspondence data is acquired and stored in the storage device 39 (62). It is assumed that the position (coordinates) on which the point of the horizontal coordinates (azmP, altP) should be displayed on the screen is obtained.
In the set of horizon coordinate one-screen coordinate correspondence data acquired previously, four values (reference points) in the horizon coordinate that surround the value to be displayed in a rectangle are selected. This is as follows.
Point 00: (azm0, alt0) (x00, y00)
Point 01: (azm1, alt0) (x01, y01)
Point 10: (azm0, alt1) (x10, y10)
Point 11: (azm1, alt1) (x11, y11)
Here, the altitudes (= alt0) of the points 00 and 01 are equal. Similarly, the azimuth angle (= azm1) of point 01 and point 11 is also equal.

It is assumed that the following relationship holds with the horizontal coordinate of the point (point P) to be displayed.
azm0 ≤ azmP ≤ azm1
alt0 ≤ altP ≤ alt1
By the way
azm1 −azm0 = dazm
alt1 −alt0 = dalt
It is.
FIG. 18 is a plot of these four reference points and point P in horizon coordinates.
Here, with the point 00 as a reference, the azimuth angle of the point P with respect to the azimuth increment value is taken as the azimuth relative value of the point P.
Azimuth relative value of point Pazmr = (azmP-azm0) / dazm
Similarly, for altitude, altitude relative value altr = (altP-alt0) / dalt
Is required.

Here, FIG. 19 is a plot of the four reference points and the point P in screen coordinates.
The screen coordinates of the point P are unknown, but interpolation is performed using the intermediate point here.
The interpolation point (xt0, yt0) between points 00 and 10 is
xt0 = (x10−x00) * altr
yt0 = (y10−y00) * altr
As required.
Similarly, the interpolation point (xt1, yt1) between points 10 and 11 is
xt1 = (x11−x01) * altr
yt1 = (y11−y01) * altr
It becomes.

Next, the on-screen coordinates (xP, yP) of the point P can be obtained by interpolating the interpolation points.
xP = (xt− xt0) * azmr
yP = (yt1 − yt0) * azmr
This embodiment is the most primitive example in which the interpolation calculation is performed by a linear expression. If the acquisition interval of the horizontal coordinate one-screen coordinate correspondence data is not sufficiently small, the accuracy of the interpolation is lowered. It can be calculated by interpolating with higher accuracy by interpolating with a high-order expression such as quadratic or cubic.
In this way, if there is a set of horizon coordinate one-screen coordinate correspondence data obtained over a sufficiently wide range, screen coordinates corresponding to an arbitrary azimuth and altitude can be acquired.

Here, the means for correcting the distortion of the image (the amount of deviation of the image from the position that should be projected by the video projector with respect to an image point such as a star by the stellar projector) is summarized as follows.
(1) Coordinate conversion is performed by interpolation calculation based on sampled screen-horizontal coordinate correspondence data (data stored in the storage means having the configuration of FIG. 7 or FIG. 8).
(2) Based on the sampled screen-horizontal coordinate correspondence data, the position, attitude angle, and other information (optical characteristics, focal length, etc.) that are parameters of the projector are calculated. Perform coordinate transformation of coordinates.
(3) Correction is performed by a method using both of the above two methods (coordinate conversion is performed by the method (2) and the remaining error is further corrected by the method (1)).

  A device that calculates the position and orientation of the true video projector by interpolating the distortion of the image projected by the video projector (deviation from the position to be projected on the projector screen) when installing a star projector and a video projector in a planetarium facility It is a system which corrects by.

It is the schematic which shows the horizontal coordinate on a dome screen. It is the figure which drew the coordinate line of the horizon coordinate by the orthogonal coordinate, and the figure which projected the coordinate line of the horizon coordinate on the screen. It is a perspective view which shows the example of an image | video projected on the screen of a projector. It is a figure which shows the example of an image projected with the correct setting of the screen of a projector. It is a figure which shows the example of an image projected when the direction of a projector has shifted | deviated 2 degree | times upwards. It is a figure which shows the example of an image | video projected when the focal distance of a lens is short. It is a side view of the dome theater which shows an example of the image projection system by this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows embodiment of the reference mark means used for the image | video projection system by this invention, (a) is what used a part of stellar projector for the projector which projects the pointer for projecting a reference mark. (B) is a stellar projector provided with a device for projecting a pointer, and (c) is provided with a device for projecting a pointer independently of the stellar projector. It is a figure for demonstrating the attitude | position angle of a projector. It is a figure for demonstrating the azimuth and altitude with respect to the position of the point image on a dome screen. It is a figure for demonstrating the position of a video projector. It is a block diagram which shows embodiment of the position alignment apparatus of the cursor of the video projection system by this invention. It is a block diagram which shows other embodiment of the alignment apparatus of the cursor of the video projection system by this invention, and is an example at the time of utilizing a camera. It is a block diagram which shows embodiment of a parameter calculation apparatus. It is a figure which shows the master image drawn with the horizon image used when converting an image into a projection screen by carrying out coordinate conversion. It is a flowchart for demonstrating the operation | movement which carries out coordinate conversion of an image, converts into a projection screen, and draws. It is the figure which showed the procedure in which a master image is coordinate-transformed and correctly projected on a dome screen. It is the figure which showed the procedure in which figure data was coordinate-transformed and correctly projected on a dome screen. It is the schematic which shows embodiment of the image | video projection system which installed the camera. It is a figure which shows the installation structure of a video projector. It is a figure for demonstrating interpolation calculation, and is the figure which displayed the screen coordinate collectively on the computer screen. It is the figure which connected and showed each point of FIG. 16 with the straight line. It is the figure which showed the four reference points of the neighborhood, and the point P enclosed by this by the horizon coordinate. It is the figure which showed the neighboring four reference points and the point P enclosed by this with screen coordinates.

Explanation of symbols

1,42,63 Dome screen 2,17,37 Stellar projector 3,33 Video projector 4 Cursor 5 Point image 6 Video projector image a
7 Computer (control device)
10, 15, 16, 41 Laser pointer (reference marker projector)
11 Support frame 12 Pedestal 18, 57 Camera 30 Cursor position operation device (mouse)
DESCRIPTION OF SYMBOLS 31 Cursor coordinate setting apparatus 32 Cursor display apparatus 34,56 Cursor image 35 Horizon coordinate setting apparatus 36 Servo control apparatus 38,61 Pointer image 39,62 Horizon coordinate 1 screen coordinate corresponding data storage apparatus 50 Video capture part 51 Image processing apparatus 52 Difference Dynamic calculator 53 Cursor coordinate setting device 65a to 65n Coordinate conversion device 1 to n
66a to 66n Screen coordinate error calculation devices 1 to n
67 Accumulator

Claims (11)

A projector capable of projecting an image output from image generation means such as a computer or a video apparatus onto a dome-shaped screen having a curved surface, and capable of projecting an image as a mark that can be arbitrarily moved on the screen;
A star projector that reproduces the starry sky on the dome-shaped screen;
Reference mark means for displaying a reference mark so that coordinates on the screen are known on the dome-shaped screen by the angular position control of the stellar projector,
Alignment means for aligning the image to be a mark projected from the projector and the reference mark at a plurality of positions on the screen;
Storage means for storing the coordinates on the projection screen of the image to be the mark coincident with the alignment means and the coordinates on the dome-shaped screen of the reference mark, and storing on- screen coordinate -screen coordinate correspondence data;
A coordinate conversion parameter calculation means for calculating a coordinate conversion parameter of a projector coordinate, an attitude angle, or a focal length of a photographing lens corresponding to each on-screen coordinate, using the on-screen coordinate-screen coordinate correspondence data;
Coordinate conversion means for performing coordinate conversion from coordinates on the screen to coordinates on the projection screen or from coordinates on the projection screen to coordinates on the screen using the coordinate conversion parameters;
With
An image projection system for displaying an image projected on the dome-shaped screen of the projector corresponding to the starry sky projected by the stellar projector with correction and displacement on the dome-shaped screen. A projector capable of projecting an image output from image generation means such as a computer or a video apparatus onto a dome-shaped screen having a curved surface, and capable of projecting an image as a mark that can be arbitrarily moved on the screen;
A star projector that reproduces the starry sky on the dome-shaped screen;
Reference mark means for displaying a reference mark so that coordinates on the screen are known on the dome-shaped screen by the angular position control of the stellar projector,
Alignment means for aligning the image to be a mark projected from the projector and the reference mark at a plurality of positions on the screen;
Storage means for storing a plurality of coordinates on the projection screen of the image serving as a mark matched by the positioning means and coordinates on the dome-shaped screen of the reference mark, and storing screen-coordinate-screen coordinate correspondence data;
Using the screen coordinate-screen coordinate correspondence data, a screen coordinate corresponding to each of a plurality of screen coordinates in the vicinity of an arbitrary position is obtained, and a screen at an arbitrary position is obtained by performing an interpolation operation on the plurality of screen coordinates. Interpolation calculation means for obtaining screen coordinates corresponding to the upper coordinates;
With
An image projection system for displaying an image projected on the dome-shaped screen of the projector corresponding to the starry sky projected by the stellar projector with correction and displacement on the dome-shaped screen. The alignment means includes
A camera for photographing the image serving as the mark and the reference mark;
The projector extracts a mark and a reference mark from a photographed image of the camera, detects a difference between the mark image position and the reference mark position, and matches the image position of the mark with the reference mark position. Control means for controlling the position of the image to be output from
The video projection system according to claim 1, further comprising:   4. The video projection system according to claim 3, wherein the camera is mounted on the reference mark means. The alignment means includes
An operating device capable of manually moving the image serving as the mark in the projection screen;
The video projection system according to claim 1, wherein an image serving as a mark is matched with the reference mark by the operation device. 6. The video projection system according to claim 1 , wherein the reference mark of the reference mark means uses a star image projected from a star projector.   6. The image according to claim 1, wherein the reference mark means is a projection device controlled to project onto coordinates on a predetermined dome-shaped screen on the dome-shaped screen. Projection system.   6. A video projection system according to claim 1, wherein said reference mark means is a projection device mounted on a stellar projector.   9. The video projection system according to claim 8, wherein the projection device sets the coordinates of the reference mark on the dome-shaped screen by controlling the angular position of the rotation axis of the stellar projector. 10. The image projection system according to claim 1 , wherein the image serving as the mark and the reference mark can be arbitrarily turned on and off.   11. The coordinate on the dome-shaped screen of the reference mark is a horizontal coordinate expressed by altitude and azimuth, wherein the reference mark is a horizon coordinate. Video projection system.

Images