WO2016104868A1

WO2016104868A1 - Image element calibration method for eliminating keystone effect in multi-projector-based reflective integrated imaging system

Info

Publication number: WO2016104868A1
Application number: PCT/KR2015/001929
Authority: WO
Inventors: 김은수; 장재영; 최희민
Original assignee: 광운대학교 산학협력단
Priority date: 2014-12-23
Filing date: 2015-02-27
Publication date: 2016-06-30
Also published as: KR101649051B1; KR20160077551A

Abstract

The present invention relates to an image element calibration method for eliminating the keystone effect in a multi-projector-based reflective integrated imaging system that is characterised by obtaining a corrected image element for a multi-projector through: step S1 of setting internal projector parameters; step S2 of calculating the geometrical position of a light beam emitted from a reference projector pixel; step S3 of calculating the geometrical position of a light beam emitted from a multi-projector pixel; step S4 of calculating the reference projector light beam that is the closest to the light beam emitted from a particular pixel of the multi-projector; step S5 of checking a mapping as to whether two light beams exist in the same lens element; step S6 of assigning the calculated reference pixel value to the particular pixel of the multi-projector; and step S7 of obtaining a calibration image element for a multi-projector.

Description

Element Image Correction Method for Eliminating Keystone Effect in Multi Projector-based Reflective Integrated Image System

The present invention provides a keystone effect in a multi-projector-based reflective integrated image system for elemental image correction to remove keystone effects in a high-efficiency / high resolution large screen multi-projector-based reflective integrated image system without intensity unevenness using multiple projectors. A method for compensating elemental images for removal.

The prior art for an integrated image including a projector is disclosed in Korean Patent Publication No. 10-0685151 for the purpose of maintaining a high quality and a high quality display for a long time in a projector and a display system including the same. A technique has been disclosed in which a video signal input by using correction data is subjected to a correction process to input a corrected signal to a liquid crystal panel, thereby maintaining good display characteristics. ; First, second and third liquid crystal panels for respectively displaying red, blue and green lights on the screen by inputting first, second and third image signals, respectively; First, second and third detection means for obtaining first, second and third display data from the red, blue and green lights, respectively; A lens cover provided to said first, second and third detection means; Liquid crystal panel drive circuits; Means for obtaining first, second and third correction data from the first, second and second display data, respectively; First, second and third memories for storing the first, second and third correction data; And first and second corrections for the first, second and third image signals based on the first, second and third correction data stored in the first, second and third memories, respectively. And second and third gamma correction circuits, wherein the display device further comprises an optical system provided between the screen and each of the first, second, and third liquid crystal panels, and the lens cover includes: A display device is provided, which is provided between each of the first, second and third liquid crystal panels.

Still another prior art includes a screen for transmitting or reflecting light in a selective direction in Korean Patent Publication No. 10-0864139; A screen illumination system comprising modules for generating different points on the screen and beams associated with different radial directions of the points on the screen; And a control system for controlling the module, wherein the screen diffuses the transmitted or reflected light according to angles between adjacent radial directions, the screen comprising: a two-dimensional display and an angle of the display; An optical system for simultaneously imaging pixels on the screen; Display pixels on a two-dimensional display that are related to different points on the screen and that correspond to different radial directions relative to these different screen points generate beams with different coordinates almost simultaneously without radial information; Imaging optics associated with a display are disclosed in which a device for simultaneously imaging beams generated in display pixels having different coordinates in different radial or imaging directions is disclosed.

However, the conventional multi-projector based reflective integrated imaging system generates a three-dimensional image using only a limited projection area and distorts the projection surface projected by the projector according to the position and tilt of each projector used in the MPII. This occurs, and distortion of the projection surface generates distortion of the element image, which hinders normal 3D image reconstruction in the MPII system.

The element image correction method for removing the keystone effect in the multi-projector based reflective integrated image system of the present invention has been devised to solve the above-described problem. Because there is no wasted projection surface, it becomes a highly efficient three-dimensional display, and the MPII system scans two-dimensional element images by using multiple projectors, and key stone artifacts are applied to each element image by the scanning conditions of the projectors. This may lead to distortion of the 3D reconstructed image, and through the present invention, it is expected that the effect of eliminating the distortion of the 3D reconstructed image by removing key stone artifacts in the 2D element image projection.

In addition, an object of the present invention is to realize a three-dimensional display by overlapping all the projector surfaces scanned by the respective projectors and generating the three-dimensional reconstructed image by overlapping the surfaces.

The element image correction method for removing the keystone effect in the multi-projector-based reflective integrated imaging system comprises the steps of: setting an internal parameter of the projector; Calculating a geometric position of a ray emitted from the reference projector pixel; Calculating a geometric position of a ray emitted from the multi-projector pixel; Step S4 of calculating a reference projector beam closest to a beam from a specific pixel of the multer projector; Step S5 of checking whether two light rays are in the same element lens; Step S6 of allocating the calculated reference pixel values to specific pixels of the multi-projector; Characterizing the element image corrected for the multi-projector through the process of S7; obtaining a calibration element image for the multi-projector.

According to the element image correction method for removing the keystone effect in the multi-projector based reflective integrated image system, the keystone effect, which is a problem of the conventional MPII system, is eliminated, and a wider projection screen surface is used than the conventional MPII system. It is possible to obtain a high resolution normal 3D image regardless of the position of the projector.

1 is a flowchart illustrating an element image correction method for removing a keystone effect in a reflection integrated imaging system based on the present invention.

2 is a block diagram of a reflection integrated imaging system based on the present invention multi-projector.

100.

Projector

200, 300. Projector

400. Mirror Array 500. Image Distribution System

The element image correction method for removing the keystone effect in the multi-projector-based reflective integrated imaging system comprises the steps of: setting an internal parameter of the projector; Calculating a geometric position of a ray emitted from the reference projector pixel; Calculating a geometric position of a ray emitted from the multi-projector pixel; Step S4 of calculating a reference projector beam closest to a beam from a specific pixel of the multer projector; Step S5 of checking whether two light rays are in the same element lens; Step S6 of allocating the calculated reference pixel values to specific pixels of the multi-projector; Acquiring the corrected element image for the multi-projector through the process of step S7 to obtain a calibration element image for the multi-projector.

In addition, the geometric position of the light beam emitted from the reference projector pixel in step S2 is that the light beam emitted from the projector reaches a different geometric position according to the position of the pixel,

It is represented by.

x _i and y _i are the geometric coordinates at which a specific pixel in the projector arrives.

R _x and R _y are the x and y axis resolution of the projector.

θ is the angle between the projector and the x axis.

φ is the angle between the projector and the z axis.

i and j are pixel indices respectively.

ε _x and ε _y are constant spread angles between two consecutive pixels.

x _p , y _p , z _p are the spatial coordinates of the projector.

In addition, the steps S1 and S2 are set at the time of setting as a basic setting process, and the steps S3 to S6 are calibration processes and the calculation is repeatedly performed for the pixels of all the

projectors

200 and 300.

The multi-projector based reflective integrated imaging system includes a mirror array 400 including a set of convex mirrors, a reference projector 100 as a reference for radiating element images to the mirror array 400, and the reference projector. It is characterized by consisting of a plurality of projectors (200, 300) installed in the vicinity of the 100, and the image distribution device 500 for sending the element image to the reference projector (100) and a plurality of projectors (200, 300). to be.

In addition, the size of the projector surface scanned by the

projectors

100, 200, and 300 is increased in proportion to the distance between the projection screen and the projector.

Hereinafter, an element image correction method for removing a keystone effect in a multi-projector based reflective integrated imaging system according to the present invention will be described in detail with reference to the accompanying drawings.

The present invention is directed to a high efficiency / high resolution large screen reflective integrated imaging system without intensity unevenness using multiple projectors.

The MPII system of the present invention generates three-dimensional reconstructed images by overlapping all projection surfaces, resulting in a high efficiency three-dimensional display because there is no wasted projection surface.

MPII stands for Multi Projection Integral Imaging.

The MPII system scans two-dimensional element images using a plurality of projectors, and key stone artifacts may be generated in each element image by scanning conditions of the projector, which leads to distortion of the three-dimensional reconstructed image.

Through the present invention, the effect of eliminating distortion of the 3D reconstructed image is expected by removing key stone artifacts in the 2D element image projection.

In addition, the three-dimensional display is realized by overlapping all the projector surfaces scanned by the respective projectors and generating the three-dimensional reconstructed image by overlapping the surfaces.

At this time, the size of the projector surface scanned by the projector is increased in proportion to the distance between the projection screen and the projector.

Since the size of the projector surface is much larger than that of a general monitor, a large screen three-dimensional display can be realized by using multiple projectors.

The MPII system consists of a mirror array and a number of projectors.

Projectors are devices that emit two-dimensional images in space.

A mirror array is a set of convex mirrors in which one convex mirror is composed of one element mirror.

Elemental images are two-dimensional images with depth and perspective information about three-dimensional objects.

Specific element images emitted from a plurality of projectors are reflected by element mirrors of the mirror array having the same index to form a 3D image.

At this time, the projection surface radiated from a plurality of projectors may not be parallel to the mirror array, which is called key stone artifact.

When key stone artifacts occur, distortion occurs that the rectangular projection planes emitted from the projectors become asymmetric rectangular projection planes.

This means that the projection plane's asymmetry means that each projector pixel was scanned at a different size.

Therefore, since pixels of different sizes are scanned in the same mirror array, a mapping mismatch problem between the element image and the mirror array occurs.

In addition, the existing MPII system has a vertical relationship between a plurality of projectors and a mirror array, wherein the element images emitted from each projector are located in the same two-dimensional plane.

At this time, since the radiation proceeds with a constant spread angle, the overlapped area of the scanning surface decreases as the number of projectors increases.

Existing MPII systems generate three-dimensional images by using overlapping portions of the radiated projection planes, and as the overlapping area decreases, the area actually used to generate the three-dimensional reconstructed image decreases.

Therefore, in order to increase the area that can be used for generating 3D images in the MPII system, it is necessary to tilt the projector appropriately to maximize the overlap area of all the projected surfaces.

In this case, key stone artifacts are generated by tilting the projector.

At this time, when the key stone artifact is removed to correct the asymmetric distortion of the projection plane scanned by each projector, the distortion of the generated 3D image may be removed.

1 is a flowchart illustrating an element image correction method for removing a keystone effect in a multi-projector based reflective integrated imaging system according to the present invention.

As shown in FIG. 1, the element image correction method for removing the keystone effect in the multi-projector based reflective integrated imaging system according to the present invention is as follows.

1. To perform the proposed calibration procedure, first set up the projector's internal parameter (S ₁ ).

Internal parameter setting (S ₁ ) is set by the projector's inherent parameters such as spread angle, resolution, depth of field, and position and tilt of the projector.

The spread angle means the angle at which light emitted from the projector spreads out in space.

Resolution is the total number of pixels that can represent an image.

Depth of field represents the physical distance at which the projection plane is clearly formed.

The position and inclination of the projectors mean the inclination of the geometric array of the plurality of projectors and the mirror array, respectively.

2. The light rays emitted from the projector reach different geometric positions according to the position of the pixel (S ₂ ).

The position to reach is represented by (Formula 1).

--- (Equation 1)

x _i and y _i denote the geometric coordinates at which a particular pixel of the projector arrives.

R _x and R _y represent the x and y axis resolution of the projector. θ means the angle between the projector and the x-axis.

φ means the angle between the projector and the z axis.

i and j mean each pixel index.

ε _x , ε _y means a constant spread angle between two consecutive pixels.

x _p , y _p , and z _p refer to the spatial coordinates of the projector.

Reference projector refers to a projector whose radiation direction is perpendicular to the mirror array display direction.

In the reference projector, the emitted element image does not need to be corrected for key stone artifacts.

In this case, the element image to be used is referred to as a reference element image.

Through Equation 1, the geometric position of ray 1 emitted from a specific pixel of the reference projector is calculated.

3. Using the formula represented by Equation 1 to calculate the geometric position of the ray 2 emitted from the multi-projector (S ₃ ).

At this time, the calculated geometric position of ray 2 is emitted at a specific pixel position of the projector to be added.

4. Calculate the geometric position of the emitted ray 1 to the position closest to the calculated position of the ray 2 (S ₄ ).

5. Check whether the same element mirror exists on the two calculated ray paths (S ₅ ).

6. If light beam 1 emitted from a specific pixel of the reference projector and light beam 2 emitted from a particular pixel location of the additional projector pass the same element mirror, then the pixel brightness value of the reference projector is added to the pixel from which beam 2 is emitted from the added projector. Assign.

This process is performed for all pixels of the projector (S ₆ ).

7. The final generated element image becomes the element image of the added projector (S ₇ ).

2 is a block diagram of a reflective integrated imaging system based on the present invention.

As shown in FIG. 2, the multi-projector-based reflective integrated imaging system of the present invention provides elementary images to the reference projector 100, the plurality of

projectors

200 and 300, the mirror array 400, and each projector as a reference. Consists of a video distribution device 500 for sending.

The reference projector 100 emits the element image to the mirror array.

In this case, the remaining

projectors

200 and 300 have different positions from the reference projector and the angle of the mirror array.

Thus, the image distribution device 500 generates the element images for the remaining

projectors

200 and 300 and puts them into the input.

Therefore, as described above, according to the element image correction method for removing the keystone effect in the multi-projector based reflective integrated image system of the present invention, the keystone effect, which is a problem of the conventional MPII system, is eliminated, and compared with the conventional MPII system. The wide projection screen surface can be used, and the remarkable effect is that a high resolution normal three-dimensional image can be obtained regardless of the position of the projector.

Claims

In the element image correction method for removing a keystone effect in a multi-projector-based reflective integrated imaging system using a multi-projector-based reflective integrated imaging system,

Step S1 of setting internal projector parameters;

Calculating a geometric position of a ray emitted from the reference projector pixel;

Calculating a geometric position of a ray emitted from the multi-projector pixel;

Step S4 of calculating a reference projector beam closest to a beam from a specific pixel of the multer projector;

Step S5 of checking whether two light rays are in the same element lens;

Step S6 of allocating the calculated reference pixel values to specific pixels of the multi-projector;

Step S7 of acquiring a calibration element image for the multi-projector;

Element image correction method for removing the keystone effect in a multi-projector based reflective integrated imaging system characterized by obtaining a corrected element image for a multi-projector through the process of.
The method of claim 1,

In the step S2, the geometric position of the light beam emitted from the reference projector pixel reaches a different geometric position according to the position of the pixel.

An element image correction method for removing a keystone effect in a multi-projector based reflective integrated imaging system characterized by

(x i , y i ; Geometric coordinates at which a specific pixel in the projector arrives

R x , R y ; X- and y-axis resolution of the projector

θ; Angle between projector and x axis

φ; Angle between projector and z axis

i, j; Each pixel index

ε x , ε y ; Spread angle between two consecutive pixels

x p , y p , z p ; Spatial coordinates of the projector)
The method of claim 1,

Steps S1 and S2 are set at the time of setting as a basic setting process, and steps S3 to S6 are calibration processes and calculations are repeatedly performed for pixels of all the projectors 200 and 300. Element Image Correction Method for Eliminating Keystone Effect in Integrated Integrated Image System.
The method of claim 1,

The multi-projector based reflective integrated imaging system includes a mirror array 400 including a set of convex mirrors, a reference projector 100 as a reference for radiating element images to the mirror array 400, and the reference projector ( Characterized in that it consists of a plurality of projectors (200, 300) installed in the vicinity of the 100, and the image distribution device 500 for sending the element image to the reference projector (100) and a plurality of projectors (200, 300) Element image correction method for removing keystone effect in multi projector based reflective integrated image system.
The method of claim 4, wherein

The size of the projector surface scanned by the projectors (100, 200, 300) is increased in proportion to the distance between the projection screen and the projector element image for removing the keystone effect in the multi-projector-based reflective integrated imaging system Correction method.