CN103792674B - A kind of apparatus and method measured and correct virtual reality display distortion - Google Patents

Abstract

The invention discloses a kind of measurement and the method for correction virtual reality display distortion, comprise the following steps: graticle obtains distortion grid picture through optical system to graticle imaging；According to the corresponding relation between mesh vertex coordinates and distortion grid apex coordinate, it is calculated the distortion factor of each grid；Distortion grid picture marks distortionless grid A, according to light path principle of reversibility, there is on the object plane of optical system the distortion grid A ' corresponding with grid A, then the apex coordinate of distortion factor and grid A is utilized, calculate the apex coordinate of distortion grid A ', and the apex coordinate of distortion grid A ' is generated coordinate look-up table；Utilize coordinate look-up table by the predistortion image that is converted to image to be projected, and input image source, and to the predistortion image imaging shown by image source, obtain image, contrast image and described predistortion image, adjust image source, complete the correction to image source.The invention also discloses a kind of measurement and the device of correction virtual reality display distortion.

Description

A kind of apparatus and method measured and correct virtual reality display distortion

Technical field

The present invention relates to projection optical system field, be specifically related to a kind of measure and correct virtual display and show Show the apparatus and method that device distorts.

Background technology

Virtual reality display is different from general scialyscope, is that word, image etc. can be believed by one Breath is directly projected on the equipment of eyes imaging by optical system, and the writings and image of projection adjusts infinite On far plane, such as head up display (HUD) and Helmet Mounted Display (HMD), it is possible to by the external world Scene together with the data fusion of display, make people just need not bow can to facilitate, comfortable The important information that he needs is seen on ground.

Virtual reality display is initially applied to military aircraft, and relate at present has wide range of applications, tool The virtual reality display (HWD) of standby intelligent operating system starts commercialization, such as Google's glasses； Have been equipped with head up display (HUD) on many commercial aircrafts, meanwhile, be assemblied in automobile, The information such as road conditions, navigation can be provided to driver more easily on train or subway train, keep away Exempt from attention interrupt and lose the grasp to state consciousness, improve the safety driven.

But, in order to be able to make the information of display not lose, observer to be made obtains comfortable sight Sense, must is fulfilled for wanting of fine definition and big visual field when designing the optical system of virtual reality display Asking, this can make projection picture be distorted, and definition is the highest, and visual field is the biggest, and the distortion of image is also The biggest, especially at peripheral field.General optical system often uses same shaft design, now schemes The distortion of picture is about centrosymmetric, but under the assembly environment that some are special, virtual reality shows Showing that the optical system of device must use the off-axis form designed, it is the biggest that this can make projection picture occur Distortion, and distortion be asymmetric.The distortion of projection picture not only can affect the comfort of observation, Even can cause observer's erroneous judgement to important information, cause unnecessary loss.Therefore, as what is the need Except the distortion of virtual reality display projection picture is urgently to be resolved hurrily.

Summary of the invention

The invention provides a kind of measurement and the method and apparatus of correction virtual reality display distortion, Image does on virtual reality display image source distortion in advance process, offset optical system and brought Distortion, reach correcting orthographic projection image distortion purpose.

A kind of method measured and correct virtual reality display distortion, comprises the following steps:

1) set the graticle with grid, this graticle is placed in the object plane of optical system, and warp Cross optical system and graticle imaging is obtained distortion grid picture, described distortion grid picture has distortion net Lattice；

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

3) on described distortion grid picture, distortionless grid A is marked, according to light path principle of reversibility, light There is on the object plane of system the distortion grid A ' corresponding with grid A, then utilize distortion factor with The apex coordinate of grid A, calculates the apex coordinate of distortion grid A ', and by the top of distortion grid A ' Point coordinates generates coordinate look-up table；

4) utilize coordinate look-up table to be converted to predistortion image by image to be projected, and input image source, And to the predistortion image imaging shown by image source, obtaining image, contrast image is with described Predistortion image, adjust image source, complete the correction to image source；

5) image source after correction is placed in the object plane of optical system, and inputs predistortion image to image source, It is distortionless image through optical system exit, completes the correction to virtual reality display.

In step 2) in, if the four of grid apex coordinates are (x₀,y₀), (x₁,y₁), (x₂,y₂) and (x₃,y₃), Four apex coordinates of distortion grid are (u₀,v₀), (u₁,v₁), (u₂,v₂) and (u₃,v₃), set up apex coordinate (x, y) with (u, v) between corresponding relation formula:

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

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

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

In step 3), if the apex coordinate of distortionless grid A is (u'_n,v'_n), according to light path Reversibility pricinple, obtains:

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

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

Present invention also offers a kind of measurement and the device of correction virtual reality display distortion, described Virtual reality display includes that optical system and image source, described device include 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 according to described distortion factor by conversion image to be projected For predistortion image；

Wherein, described systematical distortion measurement module includes:

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

Imaging device, is used for gathering undistorted grid through optical system imaging, obtains distortion grid Picture；

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

Predistortion image generation module includes:

Control system, according to described coordinate look-up table, is converted to predistortion image by image to be projected,

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

Preferably, imaging device includes camera lens and ccd sensor.

In the apparatus of the present, also include being positioned at described optical system object plane position, for described The backlight of graticle Uniform Illumination.

Described control system is respectively with backlight, image processing module and flying-spot video generator even Connecing, this control system is additionally operable to control backlight.

The present invention has simple in construction, quickly correction and advantage easy to use；Can according to system requirements To realize the correction of different accuracy；Further, since be to process by distortion image source done in advance Offset the distortion of optical system, belong to electricity correction, so optical system can meet when design as far as possible The design objective such as visual field and definition, without the impact of consideration distortion, this brings pole to designer Big convenience so that it is be with a wide range of applications.

Accompanying drawing explanation

Fig. 1 is the system flow chart that the present invention is embodied as.

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

Fig. 3 is the present invention distortionless grid graticle 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 corrects image source distortion.

Fig. 6 is the schematic diagram of projector equipment after the present invention corrects.

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

Detailed description of the invention

For making the structure of the present invention, feature and advantage become apparent from understanding, in conjunction with accompanying drawing, the whole series are filled Put and be described in further detail with method, but should not be construed as the limit of the task to scope Fixed.

As it is shown in figure 1, system flow is divided into three parts, Part I, it is that optical system distortion is surveyed Amount and predistortion image look-up table generate；Part II, is image source distortion correction；Part III, be Projector equipment after corrected.

Fig. 2 is the device schematic diagram of Part I in Fig. 1 system flow.By with undistorted grid Graticle 2 is placed in optical system 10 object plane position, if the shape of graticle 2 as it is shown on figure 3, by Dry grid composition, the correction accuracy of system requirements is the highest, and in equal area, the grid number of graduation is the most, Vice versa.

Graticle 2 imaging on ccd sensor 4 through optical system 10 and camera lens 3, institute Being imaged as the grid image with distortion, the generation of distortion is caused by optical system 10, camera Camera lens 3 uses the industrial camera camera lens of ultra-low distortion, so the distortion that camera lens brings is ignored. The image gathered is sent into image processing module 5 by ccd sensor 4, through the enhancing of image, extracts Each mesh vertex coordinates of distortion grid image also preserves.Then the coordinate figure obtained is sent at data Reason module 6, the distortion factor of calculating optical system and the look-up table of predistortion image.

In conjunction with Fig. 4, the distortion factor of calculating optical system and the mistake of the look-up table of predistortion image are described Journey.Taking the i-th row in graticle region, a grid of jth row, such as the solid line grid on the left of Fig. 4 Shown in, this grid produces distortion in image planes after optical system, such as the solid line grid institute on the right side of Fig. 4 Show, (x_n,y_n) and (u_n,v_n) it is respectively the coordinate (n=0,1,2,3) on four summits on grid.

Order $X=\left[\begin{array}{c}{x}_0\\ x_1\\ x_2\\ x_3\end{array}\right]$ $Y=\begin{array}{}\end{array}\left[\begin{array}{c}{y}_0\\ y_1\\ y_2\\ y_3\end{array}\right]$ $U=\left[\begin{array}{c}{u}_0\\ u_1\\ u_2\\ u_3\end{array}\right]$ $V=\left[\begin{array}{c}{v}_0\\ v_1\\ v_2\\ v_3\end{array}\right]$

(x₀,y₀), (x₁,y₁), (x₂,y₂) and (x₃,y₃) 4 be the quadrilateral area S and (u on summit₀,v₀), (u₁,v₁), (u₂,v₂) and (u₃,v₃) 4 be summit quadrilateral area S ' between there is functional relationship f Meet:

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

So it is considered that the arbitrfary point in quadrilateral area S ' obtains it four after function f maps Corresponding point in the S of shape region, limit.

We choose fairly simple functional relationship f and are described in detail 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:

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

Wherein, K_XAnd K_YFor the distortion factor of system, it is expressed as $K_X=\left[\begin{array}{c}{k}_{x0}\\ k_{x1}\\ k_{x2}\\ k_{x3}\end{array}\right],K_Y=\left[\begin{array}{c}{k}_{y0}\\ k_{y1}\\ k_{y2}\\ k_{y3}\end{array}\right]$

The distortion factor K of optical system can be obtained_XAnd K_Y, calculate all respectively by same method The distortion factor that grid is corresponding, returns to control system 7 by the distortion factor obtained and preserves.

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

By aforesaid optical system distortion parameter K_XAnd K_YAnd the summit of undistorted grid sits (u'_n,v'_n), according to the reversibility pricinple of light path, can release:

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

By same method, the mesh point distortionless in all image planes respective coordinates on object plane is all calculated Go out, the coordinate figure obtained is returned to control system 7, after arrangement, save as coordinate look-up table.

Fig. 5 is the device schematic diagram of system flow Fig. 1 lieutenant colonel positive image source distortion.Control system 7 is by sitting Orthoscopic image is transformed to predistortion image by mark look-up table, and inputs image source 8 and show, through pre-abnormal The image become can offset the distortion of optical system, it is achieved distortion correction.But, due to image source control The design defect of circuit or the interference of other factors, can cause image and input image source that image source shows Image inconsistent, i.e. image source can not accurately show original image information, image source to be corrected Distortion.

As it is shown in figure 5, distortionless image is transformed to predistortion by coordinate look-up table by control system 7 Image, and input image source 8 and show, the predistortion image that image source shows is through camera lens 3, at CCD Imaging on sensor 4, the image gathered is sent into image processing module 5, is contrasted defeated by ccd sensor Enter the predistortion image of display on the predistortion image of image source and image source, adjust image source, until image source shows The predistortion image shown is consistent with the predistortion image of input image source, and (both differences are in required precision scope In), then complete the correction of image source distortion.

It is illustrated in figure 6 the optical projection system schematic diagram after correction, the image source 8 after correction is placed in optics The object plane of system 10, distortionless image is transformed to predistortion by coordinate look-up table by control system 7 Image, and input image source and show, owing to image is the pre-process first passing through distortion, so predistortion figure As offsetting in distortion optical system brought through optical system 10 imaging, the most finally become Picture is distortionless image.

Only need to be in system from above-mentioned principle, the measurement of optical system distortion and the correction of image source distortion Before assembling, correction is once, and after correction, control system only need to generate predistortion by predistortion image look-up table Image input image source, then be distortionless image after optical system projects

Optical projection system distortion measurement based on principles above and correcting unit, have simple in construction, quickly Correction, the advantage such as easy to use；The correction of different accuracy can be realized according to system requirements；It addition, Processed offset the distortion of optical system by then passing through the distortion image source done in advance, belong to electricity school Just, so optical system can meet the design objective such as visual field and definition when design as far as possible, and not Needing to consider the impact of distortion, this brings great convenience to designer so that it is have a wide range of applications Prospect.

Claims (5)

1. measure and the method for correction virtual reality display distortion for one kind, it is characterised in that include Following steps:

1) set the graticle with grid, this graticle is placed in the object plane of optical system, and warp Cross optical system and graticle imaging is obtained distortion grid picture, described distortion grid picture has distortion net Lattice；

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

If the four of grid apex coordinates are (x₀,y₀), (x₁,y₁), (x₂,y₂) and (x₃,y₃), distortion grid Four apex coordinates are (u₀,v₀), (u₁,v₁), (u₂,v₂) and (u₃,v₃), set up apex coordinate (x, y) with (u, v) Between corresponding relation formula:

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

OrderThen

Wherein, K_XAnd K_YFor distortion factor, it is expressed as

3) on described distortion grid picture, distortionless grid A is marked, according to light path principle of reversibility, light There is on the object plane of system the distortion grid A ' corresponding with grid A, then utilize distortion factor with The apex coordinate of grid A, calculates the apex coordinate of distortion grid A ', and by the top of distortion grid A ' Point coordinates generates coordinate look-up table；

If the apex coordinate of distortionless grid A is (u '_n,v′_n), according to the reversibility pricinple of light path, Arrive:

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

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

4) utilize coordinate look-up table to be converted to predistortion image by image to be projected, and input image source, And to the predistortion image imaging shown by image source, obtaining image, contrast image is with described Predistortion image, adjust image source, complete the correction to image source；

5) image source after correction is placed in the object plane of optical system, and inputs predistortion image to image source, It is distortionless image through optical system exit, completes the correction to virtual reality display.

2. the side distorted based on the measurement described in claim 1 and correction virtual reality display The device of method, described virtual reality display includes optical system and image source, it is characterised in that institute The device stated includes 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 according to described distortion factor by conversion image to be projected For predistortion image；

Described systematical distortion measurement module includes:

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

Imaging device, is used for gathering undistorted grid through optical system imaging, obtains distortion grid Picture；

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

Predistortion image generation module includes:

Control system, according to described coordinate look-up table, is converted to predistortion image by image to be projected,

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

3. device as claimed in claim 2, it is characterised in that imaging device includes camera lens And ccd sensor.

4. device as claimed in claim 2, it is characterised in that also include being positioned at described optical system System object plane position, for the backlight to described graticle Uniform Illumination.

5. device as claimed in claim 4, it is characterised in that described control system respectively with Backlight, image processing module and flying-spot video generator connect, and this control system is additionally operable to control the back of the body Light source.