CN103792674A - Device and method for measuring and correcting distortion of virtual reality displayer - Google Patents

Abstract

The invention discloses a method for measuring and correcting distortion of a virtual reality displayer. The method includes the following steps that reticle imaging is carried out through an optical system to obtain a distortion grid image; a distortion coefficient of each grid is obtained through calculation according to the corresponding relationship between a vertex coordinate of the corresponding grid and a vertex coordinate of each distortion grid; non-distortion grids A are marked out on the distortion grid image, according to an optical path reversible principle, an object face of the optical system has distortion grids A' corresponding to the grids A, then vertex coordinates of the distortion grids A' are calculated by means of the distortion coefficients and the vertex coordinates of the grids A, and a coordinate look-up table is generated by means of the vertex coordinates of the distortion grids A'; an image to be projected is converted into a pre-distortion image by means of the coordinate look-up table, an image source is input, a pre-distortion image displayed by the image source is imaged, an imaging image is obtained, the imaging image is compared with the pre-distortion image, the image source is adjusted, and correcting of the image source is completed. The invention further discloses a device for measuring and correcting distortion of the virtual reality displayer.

Description

A kind of apparatus and method of measuring and proofreading and correct virtual reality display distortion

Technical field

The present invention relates to projection optical system field, be specifically related to a kind of apparatus and method of measuring and proofreading and correct virtual demonstration display distortion.

Background technology

Virtual reality display is different from general projector, a kind of equipment that the information such as word, image directly can be projected in to eyes imaging by optical system, the writings and image of projection is adjusted on plane at infinity, such as head up display (HUD) and Helmet Mounted Display (HMD), the data of extraneous scene and display can be merged, make people's important information that just can facilitate, cosily see his needs that do not need to bow.

Virtual reality display is applied to military aircraft at first, and what relate at present has wide range of applications, and the virtual reality display (HWD) that possesses intelligent operating system starts commercialization, such as Google's glasses; On many commercial aircrafts, be equipped with head up display (HUD), simultaneously, be assemblied on automobile, train or subway train and can provide the information such as road conditions, navigation to driver more easily, avoid notice to interrupt and lose the grasp to state consciousness, improve the security of driving.

But, do not lose in order to make the information showing, also to make observer obtain comfortable perception simultaneously, in the time of the optical system of design virtual reality display, must meet the requirement of high definition and large visual field, this can make projected image distort, and sharpness is higher, and visual field is larger, the distortion of image is also larger, especially in visual field, edge.General optical system often adopts coaxial design, the now distortion of image is about centrosymmetric, but under some special assembly environments, the optical system of virtual reality display must adopt from the form of axle design, this can make projected image that very large distortion occurs, and distortion is asymmetric.The distortion of projected image not only can affect the comfort of observation, even can cause the erroneous judgement of observer to important information, causes unnecessary loss.Therefore distortion, how to eliminate virtual reality display projected image is urgently to be resolved hurrily.

Summary of the invention

The invention provides a kind of method and apparatus of measuring and proofreading and correct virtual reality display distortion, on virtual reality display image source, image is done to distortion processing in advance, offset the distortion that optical system is brought, reach the object of correcting orthographic projection image's distortion.

A method of measuring and proofreading and correct virtual reality display distortion, comprises the following steps:

1) set the graticule with grid, this graticule is placed in to the object plane of optical system, and imaging obtains distortion grid picture to graticule through optical system, on described distortion grid picture, has distortion grid;

2), according to the corresponding relation between grid vertex coordinate and distortion grid apex coordinate, calculate the distortion factor of each grid;

3) on described distortion grid picture, mark distortionless grid A, according to light path principle of reversibility, on the object plane of optical system, there is the distortion grid A ' corresponding with grid A, then utilize the apex coordinate of distortion factor and grid A, calculate the apex coordinate of distortion grid A ', and the apex coordinate of distortion grid A ' is generated to coordinate look-up table;

4) utilize coordinate look-up table will treat that projected image is converted to predistortion image, and input image source, and the predistortion image imaging shown to image source, obtain image, contrast image and described predistortion image, adjustment image source, completes the correction to image source;

5) image source after proofreading and correct is placed in to the object plane of optical system, and to image source input predistortion image, is distortionless image through optical system outgoing, complete the correction to virtual reality display.

In step 2) in, four apex coordinates establishing grid are (x ₀, y ₀), (x ₁, y ₁), (x ₂, y ₂) and (x ₃, y ₃), four apex coordinates of distortion grid are (u ₀, v ₀), (u ₁, v ₁), (u ₂, v ₂) and (u ₃, v ₃), set up the corresponding relation formula between apex coordinate (x, y) and (u, v):

$\left\{\begin{array}{c}X=f_u(U,V)\\ Y=f_v(U,V)\end{array}\right.$

Order $A=\left[\begin{array}{cccc}{u}_0& v_0& u_0{v}_0& 1\\ u_1& v_1& u_1{v}_1& 1\\ u_2& v_2& u_2{v}_2& 1\\ u_3& v_3& u_3{v}_3& 1\end{array}\right],$ ? $\left\{\begin{array}{c}A\×K_X=X\\ A\×K_Y=Y\end{array}\right.;$

Wherein, K _xand K _yfor distortion factor, be expressed as $K_X=\left[\begin{array}{c}{k}_{x0}\\ k_{x1}\\ k_{x2}\\ k_{x3}\end{array}\right],K_Y=\left[\begin{array}{c}{k}_{y0}\\ k_{y1}\\ k_{y2}\\ {\mathrm{<figure-callout\; id="3"\; label="k\; y"\; filenames="HDA0000459818130000032.png"\; state="\{\{state\}\}">k</figure-callout>}}_y\end{array}\right].$

In step 3), the apex coordinate of establishing distortionless grid A is (u' _n, v' _n), according to the reciprocity principle of light path, obtain:

$\left\{\begin{array}{c}{x}_n^{\&prime;}=u_n^{\&prime;}{k}_{x0}+v_n^{\&prime;}{\mathrm{<figure-callout\; id="1"\; label="k\; x"\; filenames="HDA0000459818130000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_x+u_n^{\&prime;}{v}_n^{\&prime;}{k}_{x2}+1\&CenterDot;k_{x3}\\ y_n^{\&prime;}=u_n^{\&prime;}{k}_{y0}+v_n^{\&prime;}{\mathrm{<figure-callout\; id="1"\; label="k\; y"\; filenames="HDA0000459818130000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_y+u_n^{\&prime;}{v}_n^{\&prime;}{k}_{y2}+1\&CenterDot;{\mathrm{<figure-callout\; id="3"\; label="k\; y"\; filenames="HDA0000459818130000032.png"\; state="\{\{state\}\}">k</figure-callout>}}_y\end{array}\right.,(n=\mathrm{0,1,2},\&CenterDot;\&CenterDot;\&CenterDot;)$

Wherein, (x' _n, y' _n) apex coordinate of distortion grid A '.

The present invention also provides a kind of device of measuring and proofreading and correct virtual reality display distortion, and described virtual reality display comprises optical system and image source, and described device comprises optical system distortion measurement module and predistortion image generation module;

Described systematical distortion measurement module is for measuring the distortion factor of optical system;

Described predistortion image generation module will treat that according to described distortion factor projected image is converted to predistortion image;

Wherein, described systematical distortion measurement module comprises:

Graticule, is positioned at the object plane position of optical system, and with undistorted grid;

Imaging device, for gathering undistorted grid through optical system imaging, obtains distortion grid picture;

Image processing module, according to the corresponding relation between the distortion grid apex coordinate in distortion grid picture and undistorted grid vertex coordinate, obtains distortion factor, and generates coordinate look-up table;

Predistortion image generation module comprises:

Control system, according to described coordinate look-up table, will treat that projected image is converted to predistortion image,

Flying-spot video generator, shows for described predistortion image being sent into image source.

Preferably, imaging device comprises camera lens and ccd sensor.

In device of the present invention, also comprise and be positioned at described optical system object plane position, for the backlight to described graticule Uniform Illumination.

Described control system is connected with backlight, image processing module and flying-spot video generator respectively, and this control system is also for controlling backlight.

The present invention has advantages of simple in structure, Fast Correction and easy to use; Can realize the correction of different accuracy according to system requirements; In addition, owing to being the distortion that the distortion by image source being done in advance processes to offset optical system, belonging to electricity proofreaies and correct, so optical system can meet the design objective such as visual field and sharpness in the time of design as far as possible, and the impact that does not need consideration to distort, this brings great convenience to deviser, makes it have application prospect widely.

Accompanying drawing explanation

Fig. 1 is the concrete system flowchart of implementing of the present invention.

Fig. 2 is distortion measurement device schematic diagram in the invention process process.

Fig. 3 is the distortionless grid graticule of the present invention schematic diagram

Fig. 4 is the schematic diagram that the present invention relates to distortion and predistortion algorithm.

Fig. 5 is the device schematic diagram that the present invention proofreaies and correct image source distortion.

Fig. 6 is the schematic diagram that the present invention proofreaies and correct rear projector equipment.

In figure: 1 is that backlight, 2 is that graticule, 3 is that camera lens, 4 is that ccd sensor, 5,6 is that data processing module, 7 is that control system, 8 is that image source, 9 is that flying-spot video generator, 10 is optical system.

Embodiment

For making structure of the present invention, feature and advantage more clear, now by reference to the accompanying drawings package unit and method are described in further detail, but should not be construed as, the task of protection domain of the present invention is limited.

As shown in Figure 1, system flow is divided into three parts, and Part I is that optical system distortion measurement and predistortion image look-up table generate; Part II is image source distortion correction; Part III is the projector equipment after overcorrect.

Fig. 2 is the device schematic diagram of Part I in Fig. 1 system flow.Graticule with undistorted grid 2 is placed in to optical system 10 object plane positions, and the shape of graticule 2 as shown in Figure 3, is made up of several grids, and the correction accuracy of system requirements is higher, and in equal area, the grid number of graduation is more, and vice versa.

Graticule 2 is through optical system 10 and camera lens 3 imaging on ccd sensor 4, imaging is the grid image with distortion, the generation of distortion is caused by optical system 10, and camera lens 3 adopts the industrial camera camera lens of ultra-low distortion, so the distortion that camera lens brings is ignored.Ccd sensor 4 is sent the image of collection into image processing module 5, through the enhancing of image, extracts each grid vertex coordinate of distortion grid image and preserves.Then the coordinate figure obtaining is sent into data processing module 6, the look-up table of the distortion factor of calculating optical system and predistortion image.

The process of the distortion factor of calculating optical system and the look-up table of predistortion image is described in conjunction with Fig. 4.Get in graticule region i capable, a grid of j row, as shown in the solid line grid in Fig. 4 left side, this grid produces distortion in image planes after optical system, as shown in the solid line grid on Fig. 4 right side, (x _n, y _n) and (u _n, v _n) be respectively the coordinate (n=0,1,2,3) on four summits on grid.

Order $X=\left[\begin{array}{c}{x}_0\\ x_1\\ x_2\\ x_3\end{array}\right]$ $Y=\begin{array}{}\end{array}\left[\begin{array}{c}{y}_0\\ y_1\\ y_2\\ y_3\end{array}\right]$ $U=\left[\begin{array}{c}{u}_0\\ u_1\\ u_2\\ u_3\end{array}\right]$ $V=\left[\begin{array}{c}{v}_0\\ v_1\\ v_2\\ {\mathrm{<figure-callout\; id="3"\; label="v"\; filenames="HDA0000459818130000032.png"\; state="\{\{state\}\}">v</figure-callout>}}_3\end{array}\right]$

(x ₀, y ₀), (x ₁, y ₁), (x ₂, y ₂) and (x ₃, y ₃) 4 be the quadrilateral area S and (u on summit ₀, v ₀), (u ₁, v ₁), (u ₂, v ₂) and (u ₃, v ₃) exist a funtcional relationship f to meet between 4 quadrilateral area S ' that are summit:

$\left\{\begin{array}{c}X=f_u(U,V)\\ Y=f_v(U,V)\end{array}\right.$

We think that the arbitrfary point process function f mapping in quadrilateral area S ' obtains its corresponding point in quadrilateral area S afterwards like this.

We choose fairly simple funtcional relationship f and are elaborated below.Order

$A=\left[\begin{array}{cccc}{u}_0& v_0& u_0{v}_0& 1\\ u_1& v_1& u_1{v}_1& 1\\ u_2& v_2& u_2{v}_2& 1\\ u_3& v_3& u_3{v}_3& 1\end{array}\right]$

Meet following relation:

$\left\{\begin{array}{c}A\&times;K_X=X\\ A\&times;K_Y=Y\end{array}\right.$

Wherein, K _xand K _yfor the distortion factor of system, be expressed as $K_X=\left[\begin{array}{c}{k}_{x0}\\ k_{x1}\\ k_{x2}\\ k_{x3}\end{array}\right],K_Y=\left[\begin{array}{c}{k}_{y0}\\ k_{y1}\\ k_{y2}\\ {\mathrm{<figure-callout\; id="3"\; label="k\; y"\; filenames="HDA0000459818130000032.png"\; state="\{\{state\}\}">k</figure-callout>}}_y\end{array}\right]$

Can obtain the distortion factor K of optical system _xand K _y, use the same method and calculate respectively the distortion factor that all grids are corresponding, the distortion factor obtaining is returned to control system 7 and preserves.

Next step divides some distortionless grids in the region of distortion grid picture, and the number of grid determines according to the resolution of image source 8.Suppose that one of them undistorted grid is positioned at a certain distortion grid, dotted line as shown in Fig. 4 right side, according to the reversible principle of light path, this is undistorted grid is in the corresponding distortion grid of object plane of optical system, as shown in Fig. 4 left-hand broken line grid, (x' _n, y' _n) and (u' _n, v' _n) be respectively the coordinate (n=0,1,2,3) on four summits on grid.

By aforesaid optical system distortion parameter K _xand K _yand (u' is sat on the summit of undistorted grid _n, v' _n), according to the reciprocity principle of light path, can release:

$\left\{\begin{array}{c}{x}_n^{\&prime;}=u_n^{\&prime;}{k}_{x0}+v_n^{\&prime;}{\mathrm{<figure-callout\; id="1"\; label="k\; x"\; filenames="HDA0000459818130000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_x+u_n^{\&prime;}{v}_n^{\&prime;}{k}_{x2}+1\&CenterDot;k_{x3}\\ y_n^{\&prime;}=u_n^{\&prime;}{k}_{y0}+v_n^{\&prime;}{\mathrm{<figure-callout\; id="1"\; label="k\; y"\; filenames="HDA0000459818130000011.png"\; state="\{\{state\}\}">k</figure-callout>}}_y+u_n^{\&prime;}{v}_n^{\&prime;}{k}_{y2}+1\&CenterDot;{\mathrm{<figure-callout\; id="3"\; label="k\; y"\; filenames="HDA0000459818130000032.png"\; state="\{\{state\}\}">k</figure-callout>}}_y\end{array}\right.,(n=\mathrm{0,1,2},\&CenterDot;\&CenterDot;\&CenterDot;)$

Use the same method, the respective coordinates of distortionless net point on object plane in all image planes all calculated, the coordinate figure obtaining is returned to control system 7, after arrangement, save as coordinate look-up table.

Fig. 5 is the device schematic diagram of the positive image source distortion of system flow Fig. 1 lieutenant colonel.Control system 7 is transformed to predistortion image by coordinate look-up table by orthoscopic image, and inputs image source 8 and show, the distortion that can offset optical system through the image of predistortion, realizes distortion correction.But, due to the interference of design defect or other factors of image source control circuit, can cause the image of image that image source shows and input image source inconsistent, image source can not accurately show original image information, the distortion that therefore will proofread and correct image source.

As shown in Figure 5, control system 7 is transformed to predistortion image by coordinate look-up table by distortionless image, and input image source 8 and show, the predistortion image that image source shows is through camera lens 3, imaging on ccd sensor 4, ccd sensor is sent the image of collection into image processing module 5, the predistortion image showing on the predistortion image of contrast input image source and image source, adjust image source, until the predistortion image that image source shows and the predistortion image consistent (both differ within the scope of accuracy requirement) of inputting image source complete the correction of image source distortion.

Be illustrated in figure 6 the optical projection system schematic diagram after correction, image source 8 after proofreading and correct is placed in to the object plane of optical system 10, control system 7 is transformed to predistortion image by coordinate look-up table by distortionless image, and input image source show, because image is the processing through distortion in advance, so the distortion that predistortion image has brought optical system when through optical system 10 imaging is offset, final imaging is distortionless image.

From above-mentioned principle, the correction of the measurement of optical system distortion and image source distortion only need be proofreaied and correct once before system assembling, after correction, control system only need generate predistortion image input image source by predistortion image look-up table, after optical system projection, is distortionless image

Optical projection system distortion measurement and means for correcting based on above principle, have simple in structure, Fast Correction, the advantage such as easy to use; Can realize the correction of different accuracy according to system requirements; In addition, owing to being the distortion that the distortion by image source being done in advance processes to offset optical system, belonging to electricity proofreaies and correct, so optical system can meet the design objective such as visual field and sharpness in the time of design as far as possible, and the impact that does not need consideration to distort, this brings great convenience to deviser, makes it have application prospect widely.

Claims (7)

1. a method of measuring and proofreading and correct virtual reality display distortion, is characterized in that, comprises the following steps:

1) set the graticule with grid, this graticule is placed in to the object plane of optical system, and imaging obtains distortion grid picture to graticule through optical system, on described distortion grid picture, has distortion grid;

2), according to the corresponding relation between grid vertex coordinate and distortion grid apex coordinate, calculate the distortion factor of each grid;

3) on described distortion grid picture, mark distortionless grid A, according to light path principle of reversibility, on the object plane of optical system, there is the distortion grid A ' corresponding with grid A, then utilize the apex coordinate of distortion factor and grid A, calculate the apex coordinate of distortion grid A ', and the apex coordinate of distortion grid A ' is generated to coordinate look-up table;

4) utilize coordinate look-up table will treat that projected image is converted to predistortion image, and input image source, and the predistortion image imaging shown to image source, obtain image, contrast image and described predistortion image, adjustment image source, completes the correction to image source;

5) image source after proofreading and correct is placed in to the object plane of optical system, and to image source input predistortion image, is distortionless image through optical system outgoing, complete the correction to virtual reality display.

2. the method for measurement as claimed in claim 1 and the distortion of correction virtual reality display, is characterized in that, in step 2) in, four apex coordinates establishing grid are (x ₀, y ₀), (x ₁, y ₁), (x ₂, y ₂) and (x ₃, y ₃), four apex coordinates of distortion grid are (u ₀, v ₀), (u ₁, v ₁), (u ₂, v ₂) and (u ₃, v ₃), set up the corresponding relation formula between apex coordinate (x, y) and (u, v):

$\left\{\begin{array}{c}X=f_u(U,V)\\ Y=f_v(U,V)\end{array}\right.$

Order $A=\left[\begin{array}{cccc}{u}_0& v_0& u_0{v}_0& 1\\ u_1& v_1& u_1{v}_1& 1\\ u_2& v_2& u_2{v}_2& 1\\ u_3& v_3& u_3{v}_3& 1\end{array}\right],$ ? $\left\{\begin{array}{c}A\&times;K_X=X\\ A\&times;K_Y=Y\end{array}\right.;$

Wherein, K _xand K _yfor distortion factor, be expressed as $K_X=\left[\begin{array}{c}{k}_{x0}\\ k_{x1}\\ k_{x2}\\ k_{x3}\end{array}\right],K_Y=\left[\begin{array}{c}{k}_{y0}\\ k_{y1}\\ k_{y2}\\ k_{y3}\end{array}\right].$

3. the method for measurement as claimed in claim 2 and the distortion of correction virtual reality display, is characterized in that, in step 3), the apex coordinate of establishing distortionless grid A is (u' _n, v' _n), according to the reciprocity principle of light path, obtain:

$\left\{\begin{array}{c}{x}_n^{\&prime;}=u_n^{\&prime;}{k}_{x0}+v_n^{\&prime;}{k}_{x1}+u_n^{\&prime;}{v}_n^{\&prime;}{k}_{x2}+1\&CenterDot;k_{x3}\\ y_n^{\&prime;}=u_n^{\&prime;}{k}_{y0}+v_n^{\&prime;}{k}_{y1}+u_n^{\&prime;}{v}_n^{\&prime;}{k}_{y2}+1\&CenterDot;k_{y3}\end{array}\right.,(n=\mathrm{0,1,2},\&CenterDot;\&CenterDot;\&CenterDot;)$

Wherein, (x' _n, y' _n) apex coordinate of distortion grid A '.

4. a device of measuring and proofread and correct virtual reality display distortion, described virtual reality display comprises optical system and image source, it is characterized in that, described device comprises optical system distortion measurement module and predistortion image generation module;

Described systematical distortion measurement module is for measuring the distortion factor of optical system;

Described predistortion image generation module will treat that according to described distortion factor projected image is converted to predistortion image;

Described systematical distortion measurement module comprises:

Graticule, is positioned at the object plane position of optical system, and with undistorted grid;

Imaging device, for gathering undistorted grid through optical system imaging, obtains distortion grid picture;

Image processing module, according to the corresponding relation between the distortion grid apex coordinate in distortion grid picture and undistorted grid vertex coordinate, obtains distortion factor, and generates coordinate look-up table;

Predistortion image generation module comprises:

Control system, according to described coordinate look-up table, will treat that projected image is converted to predistortion image,

Flying-spot video generator, shows for described predistortion image being sent into image source.

5. the device of measurement as claimed in claim 4 and the distortion of correction virtual reality display, is characterized in that, imaging device comprises camera lens and ccd sensor.

6. the device of measurement as claimed in claim 4 and the distortion of correction virtual reality display, is characterized in that, also comprises and is positioned at described optical system object plane position, for the backlight to described graticule Uniform Illumination.

7. the device of measurement as claimed in claim 6 and the distortion of correction virtual reality display, is characterized in that, described control system is connected with backlight, image processing module and flying-spot video generator respectively, and this control system is also for controlling backlight.

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