METHOD AND APPARATUS FOR MEASURING OPTICAL CHARACTERISTICS OF AUGMENTED REALITY DEVICE

Abstract

A method and apparatus for measuring optical characteristics of an augmented reality device are disclosed. A method of measuring optical characteristics of an augmented reality device according to an exemplary embodiment of the present invention includes: taking a test image including a plurality of patterns that is output on a virtual plane by the augmented reality device, using at least one camera disposed around a predetermined measurement reference position; acquiring field of view information including information about the field of view of the at least one camera, and photographing system information including information about the arrangement of the at least one camera; and calculating the coordinates of a plurality of patterns with respect to the measurement reference position on the basis of a plurality of captured images taken by the at least one camera, field of view information, and photographing system information.

Claims

1-28 (canceled)

29. A measuring configuration method for a virtual image by an apparatus, the method comprising: acquiring an image including at least one of patterns displayed on the virtual image plane by using at least one of cameras; obtaining information on capturing system including information on an angle of view related with the at least one of cameras; and measuring coordinates of the at least one of patterns based on the information on capturing system and a plurality of images captured by the at least one of cameras.

30. The method according to claim 29, wherein the at least one of cameras captures the image at a central acquiring position, a left acquiring position and a right acquiring position located symmetrically around the measurement reference position.

31. The method according to claim 30, wherein coordinates of the at least one of patterns are determined based on an angle of view of the at least one of cameras, a distance between the left acquiring position and the right acquiring position, and the number of horizontal pixels of the image.

32. The method according to claim 30, the method further comprising, calculating a virtual image distance between the measurement reference position and the virtual plane based on the at least one of coordinates of the last one of patterns.

33. The method according to claim 30, the method further comprising, calculating a look down angle and a look over angle for the virtual plane from the measurement reference position based on at least one of the coordinates of the measurement reference position and at least one of coordinates of the at least one of patterns.

34. The method according to claim 30, the method further comprising, calculating a horizontal viewing angle of the measurement reference position based on the coordinates of the measurement reference position and coordinates of two patterns located at both ends in the horizontal direction among the at least one of patterns.

35. The method according to claim 29, the method further comprising, measuring distortion for each of the three axes of the measurement reference position based on coordinates of the at least one of pattern on the virtual image.

36. An apparatus for measuring light, the apparatus comprising: an acquirer configured to acquire an image including at least one of patterns displayed on the virtual image plane by using at least one of cameras; an obtainer configured to obtain information on capturing system including information on an angle of view related with the at least one of cameras; and processor configured to measure coordinates of the at least one of patterns based on the information on capturing system and a plurality of images captured by the at least one of cameras.

37. The apparatus according to claim 36, wherein the at least one of cameras captures the image at a central acquiring position, a left acquiring position and a right acquiring position located symmetrically around the measurement reference position.

38. The apparatus according to claim 37, wherein coordinates of the at least one of patterns are determined based on an angle of view of the at least one of cameras, a distance between the left acquiring position and the right acquiring position, and the number of horizontal pixels of the image.

39. The apparatus according to claim 37, wherein the processor is further configured to calculate a virtual image distance between the measurement reference position and the virtual plane based on the at least one of coordinates of the last one of patterns.

40. The apparatus according to claim 37, wherein the processor is further configured to calculate a look down angle and a look over angle for the virtual plane from the measurement reference position based on at least one of the coordinates of the measurement reference position and at least one of coordinates of the at least one of patterns.

41. The apparatus according to claim 37, wherein the processor is further configured to calculate a horizontal viewing angle of the measurement reference position based on the coordinates of the measurement reference position and coordinates of two patterns located at both ends in the horizontal direction among the at least one of patterns.

42. The apparatus according to claim 36, wherein the processor is further configured to measure distortion for each of the three axes of the measurement reference position based on coordinates of the at least one of pattern on the virtual image.

Description

DESCRIPTION OF DRAWINGS

[0053] FIG. 1 is a flowchart showing a method of measuring optical characteristics of an augmented reality device according to an exemplary embodiment of the present invention.

[0054] FIG. 2 is a flowchart showing a method of calculating a virtual image distance according to an exemplary embodiment of the present invention.

[0055] FIG. 3 is a flowchart showing a method of calculating a look down/up angle according to an exemplary embodiment of the present invention.

[0056] FIG. 4 is a flowchart showing a method of calculating a horizontal field of view according to an exemplary embodiment of the present invention.

[0057] FIG. 5 is a flowchart showing a method of calculating a vertical field of view according to an exemplary embodiment of the present invention.

[0058] FIG. 6 is a flowchart showing a method of calculating a static distortion according to an exemplary embodiment of the present invention.

[0059] FIG. 7 is a flowchart showing a method of calculating a ghosting level according to an exemplary embodiment of the present invention.

[0060] FIG. 8 is a block diagram showing an apparatus for measuring optical characteristics of an augmented reality device according to an exemplary embodiment of the present invention.

[0061] FIGS. 9A and 9B are diagrams for explaining an environment for measuring optical characteristics of an augmented reality device according to an exemplary embodiment of the present invention.

[0062] FIG. 10 is a diagram for explaining the result of taking a test image on a virtual plane using at least one camera according to an exemplary embodiment of the present invention.

[0063] FIGS. 11A and 11B are diagrams for explaining the coordinates of a plurality of patterns included in a captured image taken using at least one camera according to an exemplary embodiment of the present invention.

[0064] FIGS. 12A and 12B are diagrams for explaining a method of calculating the coordinates of a plurality of patterns according to an exemplary embodiment of the present invention.

[0065] FIG. 13 is a diagram for explaining a method of calculating a virtual image distance according to an exemplary embodiment of the present invention.

[0066] FIGS. 14A and 14B are diagrams for explaining a method of calculating a look down/up angle according to an exemplary embodiment of the present invention.

[0067] FIGS. 15A and 15B are diagrams for explaining a method of calculating a horizontal field of view and a vertical field of view of a plurality of patterns according to an exemplary embodiment of the present invention.

[0068] FIG. 16 is a diagram for explaining a method of calculating a static distortion according to an exemplary embodiment of the present invention.

[0069] FIG. 17 is a diagram for explaining a method of calculating a ghosting level according to an exemplary embodiment of the present invention.

BEST MODE

[0070] The present invention may be modified in various ways and implemented by various exemplary embodiments, so that specific exemplary embodiments are shown in the drawings and will be described in detail herein. However, it is to be understood that the present invention is not limited to the specific exemplary embodiments, but includes all modifications, equivalents, and substitutions included in the spirit and the scope of the present invention. Similar reference numerals are assigned to similar components in the following description of drawings.

[0071] Terms used in the specification, ‘first’, ‘second’, ‘A’, ‘B’, etc., may be used to describe various components, but the components are not to be construed as being limited to the terms. The terms are used only to distinguish one component from another component. For example, the ‘first’ component may be named the ‘second’ component, and vice versa, without departing from the scope of the present invention. The term ‘and/or’ includes a combination of a plurality of relevant items or any one of a plurality of relevant terms.

[0072] It is to be understood that when one element is referred to as being “connected to” or “coupled to” another element, it may be connected directly to or coupled directly to another element or be connected to or coupled to another element, having the other element intervening therebetween. On the other hand, it should be understood that when one element is referred to as being “connected directly to” or “coupled directly to” another element, it may be connected to or coupled to another element without the other element intervening therebetween.

[0073] Terms used in the present specification are used only to describe specific exemplary embodiments rather than limiting the present invention. Singular forms are intended to include plural forms unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” or “have” used in this specification, specify the presence of stated features, numerals, steps, operations, components, parts, or a combination thereof, but do not preclude the presence or addition of one or more other features, numerals, steps, operations, components, parts, or a combination thereof.

[0074] Unless defined otherwise, it is to be understood that all the terms used in the specification including technical and scientific terms have the same meaning as those that are understood by those who are skilled in the art. It will be further understood that terms such as terms defined in common dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0075] Hereinafter, preferred exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0076] The present invention relates to a method and apparatus for measuring optical characteristics of an augmented reality device and measurement may be performed under the following environments. For example, referring to FIG. 9A, the eyes of a user may be positioned in an eye box and a virtual plane output by a virtual reality device may be formed outside a transparent or translucent screen (e.g., the windshield of a vehicle). In this case, the user can see the entire virtual plane by moving only the eyes. Further, referring to FIG. 9B, a plurality of cameras may be disposed around a measurement reference position in an eye box. In more detail, cam.sub.C may be disposed at the measurement reference position, and cam.sub.L and cam.sub.R may be disposed at symmetric positions at both sides thereof. Meanwhile, a plurality of patterns may be horizontally and vertically arranged (e.g., 3×3) in a test image.

[0077] However, it should be noted that the present invention is not limited as being achieved only in this environment and may be achieved in various different environments. For example, the position and size of the eye box, the number and arrangement of cameras, the number and arrangement of patterns included in the test image, etc. may depend on the measurement environment.

[0078] FIG. 1 is a flowchart showing a method of measuring optical characteristics of an augmented reality device according to an exemplary embodiment of the present invention.

[0079] In step S110, an apparatus for measuring optical characteristics takes a test image including a plurality of patterns that is output on a virtual plane by an augmented reality device, using at least one camera disposed around a predetermined measurement reference position.

[0080] For example, referring to FIG. 9B, one camera may be disposed at a measurement reference position at the center of the eye box, and the other cameras may be symmetrically disposed to face the front at the same heights at both sides thereof.

[0081] In this case, the apparatus for measuring optical characteristics is connected with a plurality of cameras through wireless or wired, thereby being able to transmit an instruction to take a test image on the virtual plane.

[0082] Further, one camera may take a test image at a plurality of positions while moving. For example, one camera may move along the arrow shown in FIG. 9B and may take a test image at each of the cam.sub.L position (left position of the measurement reference position), cam.sub.C position (measurement reference position), and cam.sub.R position (right position of the measurement reference position).

[0083] Meanwhile, the example described above is only an exemplary embodiment of the present invention and the right range of the present invention should not be limited to the example described above.

[0084] In step S120, the apparatus for measuring optical characteristics acquires field of view information including information about the field of view of the at least one camera, and photographing system information including information about the arrangement of the at least one camera.

[0085] For example, the apparatus for measuring optical characteristics may acquire field of view information and photographing system information by receiving information of the field of view of a camera and information about the arrangement of a camera from a user. Preferably, the information about the field of view of a camera may be a horizontal field of view and the information about the arrangement of a camera may be the distance between cameras symmetrically disposed at both sides of the measurement reference position. Alternatively, as described above, when one camera takes a test image while moving, the photographing system information may be the distance between a left photographing position and a right photographing position symmetrically defined at both sides of the measurement reference position.

[0086] Finally, in step S130, the apparatus for measuring optical characteristics calculates the coordinates of a plurality of patterns with respect to the measurement reference position on the basis of a plurality of captured images taken by the at least one camera, field of view information, and photographing system information.

[0087] In this case, the apparatus for measuring optical characteristics may calculate 3D coordinates of a plurality of patterns on a virtual plane having the measurement reference position as the origin (0, 0, 0), using information about the sizes of a plurality of captured images, information about the coordinates of a plurality of patterns included in the plurality of captured images in the images, information about the field of view of at least one camera, and information about the arrangement of the at least one camera.

[0088] Meanwhile, a detailed method of calculating the coordinates of a plurality of patterns will be described in detail in the following exemplary embodiment.

[0089] In another exemplary embodiment, when the at least one camera includes a central camera positioned at the measurement reference position, and a left camera and a right camera symmetrically positioned with the measurement reference position therebetween and when a plurality of patterns is horizontally and vertically arranged in one test image, the apparatus for measuring optical characteristics may calculate the coordinates of a plurality of patterns, using the number of horizontal pixels of a plurality of captured images, the coordinates of a plurality of patterns in the plurality of captured images, the field of view of the at least one camera included in field of view information, and the distance between the left camera and the right camera included in the photographing system information.

[0090] For example, referring to FIG. 9B, at least one camera may be a central camera cam.sub.C positioned at the measurement reference position, and a left camera cam.sub.L and a right camera cam.sub.R symmetrically positioned with the measurement reference position therebetween. Further, nine patterns may be horizontally and vertically arranged in a test image.

[0091] In this case, the apparatus for measuring optical characteristics may calculate the 3D coordinates of each of the nine patterns on the virtual plane having the measurement reference position as the origin (0, 0, 0), using the number of horizontal pixels of a plurality of captured images, the coordinates of a plurality of patterns in the plurality of captured images, the field of view of the at least one camera included in field of view information, and the distance between the left camera and the right camera included in photographing system information.

[0092] In another exemplary embodiment, when the apparatus for measuring optical characteristics takes pictures at a central photographing position where the at least one camera takes a picture at the measurement reference position, and a left photographing position and a right photographing position that are symmetrically positioned with the measurement reference position therebetween and the plurality of patterns is horizontally and vertically arranged in the test image, the apparatus for measuring optical characteristics may calculate the coordinates of the plurality of patterns, using the number of horizontal pixels of the plurality of captured images, the coordinates of the plurality of patterns in the plurality of captured images, the field of view of the at least one camera included in the field of view information, and the distance between the left photographing position and the right photographing position included in the photographing system information.

[0093] In another exemplary embodiment, the apparatus for measuring optical characteristics may calculate the coordinates of a plurality of patterns, using Formula 1.

[00009]$\begin{array}{cc}{z}_{\mathrm{ij}}=\frac{\alpha }{2.Math.\tan \frac{\theta }{2}}.Math.\frac{M}{\left(m_{ij}^L-m_{ij}^R\right)}{x}_{ij}=z_{ij}.Math.\tan \frac{\theta }{2}\left(2.Math.\frac{m_{\mathrm{ij}}^C}{M}-1\right)y_{ij}=z_{ij}.Math.\tan \frac{\theta }{2}\left(2.Math.\frac{n_{ij}^C}{M}-1\right)& \left[\mathrm{Formula}1\right]\end{array}$

[0094] where x.sub.ij, y.sub.ij, and z.sub.ij are x-axial, y-axial, and z-axial coordinates of the horizontal i-th and vertical j-th pattern with respect to the measurement reference position, α is the distance between the left camera and the right camera, M is the number of horizontal pixels of a plurality of captured images, θ is the field of view of at least one camera, m.sup.L.sub.ij is the horizontal coordinate of the horizontal i-th and vertical j-th pattern in the captured image of the left camera, m.sup.R.sub.ij is the horizontal coordinate of the horizontal i-th and vertical j-th pattern in the captured image of the right camera, and m.sup.C.sub.ij is the horizontal coordinate of the horizontal i-th and vertical j-th pattern in the captured image of the central camera.

[0095] In this case, referring to FIG. 10, a central camera cam.sub.C may be disposed at the measurement reference position that is the center of an eye box, and left camera cam.sub.L and a right camera cam.sub.R may be disposed with a distance a therebetween. Further, the apparatus for measuring optical characteristics may take a test image on a virtual plane, using the central camera cam.sub.C, the left camera cam.sub.L, and the right camera cam.sub.R that are disposed to face the front. As a result, the test image of the captured image by cam.sub.L taken using the left camera cam.sub.L may be biased to the right, the test image of the captured image by cam.sub.C taken using the central camera cam.sub.C may not be biased, and the test image of the captured image by cam.sub.R taken using the right camera cam.sub.R may be biased to the left.

[0096] Meanwhile, referring to FIG. 11A, the 3D coordinates of nine patterns shown in a virtual plane may be expressed by P.sub.ij=(x.sub.ij, y.sub.ij, z.sub.ij), where I may be the horizontal index (i=1, 2, 3) of the patterns and j may be the vertical index (j=1, 2, 3) of the patterns. That is, P.sub.ij may be the 3D coordinates of the center of the horizontal i-th and vertical j-th pattern.

[0097] Further, referring FIG. 11B, the pixel coordinates of nine patterns shown in a captured image may be expressed as P.sup.L.sub.ij, P.sup.C.sub.ij, and P.sup.R.sub.ij, and may mean the coordinates of patterns shown in the captured image of each of the left camera cam.sub.L, the central camera cam.sub.C, and the right camera cam.sub.R. In this case, p.sup.L.sub.ij=(m.sup.L.sub.ij, n.sup.L.sub.ij), P.sup.C.sub.ij=(m.sup.C.sub.ij, n.sup.C.sub.ij), and P.sup.R.sub.ij=(m.sup.R.sub.ij, n.sup.R.sub.ij). In this case, P.sup.L.sub.ij, P.sup.C.sub.ij, and P.sup.R.sub.ij may be pixel coordinates of the center of the horizontal i-th and vertical j-th pattern.

[0098] Meanwhile, referring to FIG. 12A, it can be seen that a proportional relationship like the following Formula 2 is formed.

[00010]$\begin{array}{cc}\frac{\alpha }{2\times z\times \tan \left(\theta \text{/}2\right)}=\frac{m_{ij}^L-m_{ij}^R}{M}& \left[\mathrm{Formula}2\right]\end{array}$

[0099] where z is the z-axial distance from a measurement reference position to a virtual plane, θ is the field of view of a camera, α is the distance between a left camera and a right camera, m.sup.L.sub.ij is the horizontal coordinate of a horizontal i-th and vertical j-th pattern in the captured image of the left camera, m.sup.R.sub.ij is the horizontal coordinate of a horizontal i-th and vertical j-th pattern in the captured image of the right camera, and M is the number of horizontal pixels of a captured image.

[0100] In this case, it is apparent that Formula 1 may be obtained by changing Formula 2.

[0101] For example, referring to FIG. 12B, the apparatus for measuring optical characteristics may calculate x.sub.11, y.sub.11, and z.sub.11 through Formula 1, using the result of taking pictures using the central camera cam.sub.C, the left camera cam.sub.L, and the right camera cam.sub.R for the same pattern (i=1 and j=1).

[0102] FIG. 2 is a flowchart showing a method of calculating a virtual image distance according to an exemplary embodiment of the present invention.

[0103] In step S210, an apparatus for measuring optical characteristics takes a test image including a plurality of patterns that is output on a virtual plane by an augmented reality device, using at least one camera disposed around a predetermined measurement reference position.

[0104] In step S220, the apparatus for measuring optical characteristics acquires field of view information including information about the field of view of the at least one camera, and photographing system information including information about the arrangement of the at least one camera.

[0105] In step S230, the apparatus for measuring optical characteristics calculates the coordinates of a plurality of patterns with respect to the measurement reference position on the basis of a plurality of captured images taken by the at least one camera, field of view information, and photographing system information.

[0106] Finally, in step S240, the apparatus for measuring optical characteristics calculates a virtual image distance between the measurement reference position and the virtual plane, using the coordinates of the measurement reference position and the coordinates of at least one of the plurality of patterns.

[0107] For example, referring to FIG. 13, the apparatus for measuring optical characteristics may calculate a virtual image distance by calculating the distance from (0, 0, 0) that is the measurement reference position to the coordinates (x.sub.22, y.sub.22, z.sub.22) of P.sub.22.

[0108] In another exemplary embodiment, the apparatus for measuring optical characteristics may calculate a virtual image distance, using Formula 3.

D.sub.VI=√{square root over (x.sub.22.sup.2+y.sub.22.sup.2+z.sub.22.sup.2)}   [Formula 3]

[0109] where D.sub.VI is a virtual image distance, and x.sub.22, y.sub.22, and z.sub.22 are 3D coordinates of the pattern of i=2 and j=2.

[0110] FIG. 3 is a flowchart showing a method of calculating a look down/up angle according to an exemplary embodiment of the present invention.

[0111] In step S310, an apparatus for measuring optical characteristics takes a test image including a plurality of patterns that is output on a virtual plane by an augmented reality device, using at least one camera disposed around a predetermined measurement reference position.

[0112] In step S320, the apparatus for measuring optical characteristics acquires field of view information including information about the field of view of the at least one camera, and photographing system information including information about the arrangement of the at least one camera.

[0113] In step S330, the apparatus for measuring optical characteristics calculates the coordinates of a plurality of patterns with respect to the measurement reference position on the basis of a plurality of captured images taken by the at least one camera, field of view information, and photographing system information.

[0114] Finally, in step S340, the apparatus for measuring optical characteristics calculates a look down/up angle to the virtual plane from the measurement reference position, using the coordinates of the measurement reference position and the coordinates of at least one of the plurality of patterns.

[0115] The look down/up angle, which is the angle showing the height difference between an eye box and a virtual plane, shows whether a user looks up or looks down the virtual plane.

[0116] For example, when the coordinates (x.sub.22, y.sub.22, z.sub.22) of P.sub.22 are calculated with respect to (0, 0, 0) that is the measurement reference position where the user's eyes are positioned, it may be a looking-down situation if y.sub.22<0, as shown in FIG. 14A, and it may be a looking-up situation if y.sub.22>0, as shown in FIG. 14B.

[0117] In another exemplary embodiment, the apparatus for measuring optical characteristics may calculate look down/up angle, using Formula 4.

[00011]$\begin{array}{cc}{\theta }_{down/up}={\cos }^{-1}\frac{\sqrt{x_{22}^2+z_{22}^2}}{\sqrt{x_{22}^2+y_{22}^2+z_{22}^2}}& \left[\mathrm{Formula}4\right]\end{array}$

[0118] where θ.sub.down/up is a look down/up angle, and x.sub.22, y.sub.22, and z.sub.22 are 3D coordinates of the pattern of i=2 and j=2.

[0119] FIG. 4 is a flowchart showing a method of calculating a horizontal field of view according to an exemplary embodiment of the present invention.

[0120] In step S410, an apparatus for measuring optical characteristics takes a test image including a plurality of patterns that is output on a virtual plane by an augmented reality device, using at least one camera disposed around a predetermined measurement reference position.

[0121] In step S420, the apparatus for measuring optical characteristics acquires field of view information including information about the field of view of the at least one camera, and photographing system information including information about the arrangement of the at least one camera.

[0122] In step S430, the apparatus for measuring optical characteristics calculates the coordinates of a plurality of patterns with respect to the measurement reference position on the basis of a plurality of captured images taken by the at least one camera, field of view information, and photographing system information.

[0123] Finally, in step S440, the apparatus for measuring optical characteristics calculates the horizontal field of view of the measurement reference position, using the coordinates of the measurement reference position and the coordinates of two patterns positioned at both horizontal ends of the plurality of patterns on the virtual plane.

[0124] For example, referring to FIG. 15A, the apparatus for measuring optical characteristics may calculate an angle ∠P.sub.21OP.sub.23 as a horizontal field of view, using the 3D coordinates O=(0, 0, 0) of the measurement reference position and the 3D coordinates of two patterns P.sub.21=(x.sub.21, y.sub.21, z.sub.21) and P.sub.23=(x.sub.23, y.sub.23, z.sub.23) positioned at both horizontal ends of the plurality of patterns on the virtual plane.

[0125] In another exemplary embodiment, the apparatus for measuring optical characteristics may calculate a horizontal field of view, using Formula 5.

[00012]$\begin{array}{cc}{\theta }_{FOV}^H={\cos }^{-1}\frac{{.Math.\stackrel{\_}{P_{21}O}.Math.}^2+{.Math.\stackrel{\_}{P_{23}O}.Math.}^2-{.Math.\stackrel{\_}{P_{21}{P}_{23}}.Math.}^2}{2.Math..Math.\stackrel{\_}{P_{21}O}.Math..Math.\stackrel{\_}{P_{23}O}.Math.}& \left[\mathrm{Formula}5\right]\end{array}$

[0126] where θ.sup.H.sub.FOV is a horizontal field of view, O is the coordinate of a measurement reference position, and P.sub.21 and P.sub.23 are coordinates of two patterns positioned at both horizontal ends of a plurality of patterns.

[0127] FIG. 5 is a flowchart showing a method of calculating a vertical field of view according to an exemplary embodiment of the present invention.

[0128] In step S510, an apparatus for measuring optical characteristics takes a test image including a plurality of patterns that is output on a virtual plane by an augmented reality device, using at least one camera disposed around a predetermined measurement reference position.

[0129] In step S520, the apparatus for measuring optical characteristics acquires field of view information including information about the field of view of the at least one camera, and photographing system information including information about the arrangement of the plurality of cameras.

[0130] In step S530, the apparatus for measuring optical characteristics calculates the coordinates of a plurality of patterns with respect to the measurement reference position on the basis of a plurality of captured images taken by the at least one camera, field of view information, and photographing system information.

[0131] Finally, in step S540, the apparatus for measuring optical characteristics calculates the vertical field of view of the measurement reference position, using the coordinates of the measurement reference position and the coordinates of two patterns positioned at both vertical ends of the plurality of patterns on the virtual plane.

[0132] For example, referring to FIG. 15B, the apparatus for measuring optical characteristics may calculate an angle ∠P.sub.12OP.sub.32 as a vertical field of view, using the 3D coordinates O=(0, 0, 0) of the measurement reference position and the 3D coordinates of two patterns P.sub.12=(x.sub.12, y.sub.12, z.sub.12) and P.sub.32=(x.sub.32, y.sub.32, z.sub.32) positioned at both vertical ends of the plurality of patterns on the virtual plane.

[0133] In another exemplary embodiment, the apparatus for measuring optical characteristics may calculate a vertical field of view, using Formula 6.

[00013]$\begin{array}{cc}{\theta }_{FOV}^V={\cos }^{-1}\frac{{.Math.\stackrel{\_}{P_{12}O}.Math.}^2+{.Math.\stackrel{\_}{P_{32}O}.Math.}^2-{.Math.\stackrel{\_}{P_{12}{P}_{32}}.Math.}^2}{2.Math..Math.\stackrel{\_}{P_{12}O}.Math..Math.\stackrel{\_}{P_{32}O}.Math.}& \left[\mathrm{Formula}6\right]\end{array}$

[0134] where θ.sup.V.sub.FOV is a vertical field of view, O is the coordinate of a measurement reference position, and P.sub.12 and P.sub.32 are coordinates of two patterns positioned at both vertical ends.

[0135] FIG. 6 is a flowchart showing a method of calculating a static distortion according to an exemplary embodiment of the present invention.

[0136] In step S610, an apparatus for measuring optical characteristics takes a test image including a plurality of patterns that is output on a virtual plane by an augmented reality device, using at least one camera disposed around a predetermined measurement reference position.

[0137] In step S620, the apparatus for measuring optical characteristics acquires field of view information including information about the field of view of the at least one camera, and photographing system information including information about the arrangement of the at least one camera.

[0138] In step S630, the apparatus for measuring optical characteristics calculates the coordinates of a plurality of patterns with respect to the measurement reference position on the basis of a plurality of captured images taken by the at least one camera, field of view information, and photographing system information.

[0139] Finally, in step S640, the apparatus for measuring optical characteristics calculates a static distortion for each of three axes with respect to the measurement reference position on the basis of the coordinates of the plurality of patterns on the virtual plane.

[0140] In this case, referring to FIG. 16, the static distortion, which is induced by projection of a virtual reality device, shows the deviation degree of 3D coordinates of a plurality of patterns from a line corresponding to each of three axes (x, y, z).

[0141] Meanwhile, the apparatus for measuring optical characteristics may calculate a static distortion for each of three axes, using Formula 7.

[00014]$\begin{array}{cc}{\mathrm{DT}}_{\mathrm{Linearity}}^x=\frac{\underset{i=1}{\overset{3}{.Math.}}.Math.x_{i1}+x_{i3}-2x_{i2}.Math.}{3}D{T}_{\mathrm{Linearity}}^y=\frac{\underset{i=1}{\overset{3}{.Math.}}.Math.y_{1i}+y_{3i}-2y_{2i}.Math.}{3}D{T}_{\mathrm{Linearity}}^z=\frac{\underset{i=1}{\overset{3}{.Math.}}.Math.z_{1i}+z_{3i}-2z_{2i}.Math.}{6}+\frac{\underset{i=1}{\overset{3}{.Math.}}.Math.z_{i1}+z_{i3}-2z_{i2}.Math.}{6}& \left[\mathrm{Formula}7\right]\end{array}$

[0142] where DT.sup.x.sub.Linearity, DT.sup.y.sub.Linearity, and DT.sup.z.sub.Linearity are linear distortion values from x, y, and z axes, respectively, and x.sub.ab, y.sub.ab, and z.sub.ab are x, y, and z coordinates of the horizontal a-th (a=1, 2, 3) and vertical b-th (b=1, 2, 3) pattern, respectively.

[0143] FIG. 7 is a flowchart showing a method of calculating a ghosting level according to an exemplary embodiment of the present invention.

[0144] In step S710, an apparatus for measuring optical characteristics takes a test image including a plurality of patterns that is output on a virtual plane by an augmented reality device, using at least one camera disposed around a predetermined measurement reference position.

[0145] In step S720, the apparatus for measuring optical characteristics acquires field of view information including information about the field of view of the at least one camera, and photographing system information including information about the arrangement of the at least one camera.

[0146] In step S730, the apparatus for measuring optical characteristics calculates the coordinates of a plurality of patterns and the coordinates of a plurality of ghost patterns with respect to the measurement reference position on the basis of a plurality of captured images taken by the at least one camera, field of view information, and photographing system information.

[0147] For example, a ghost pattern may be generated on an automotive windshield that transmits a half of input light and reflects the other half. In more detail, referring to FIG. 17, two physical layers of a windshield cause a ghost phenomenon, so a pattern on a virtual plane and a ghost pattern corresponding to the pattern may be seen overlapping like double images or may be seen blurred to a user.

[0148] In this case, the apparatus for measuring optical characteristics may calculate the coordinates of a plurality of ghost patterns corresponding to the coordinates of a plurality of patterns, respectively, in the same way as the method of calculating the coordinates of a plurality of patterns.

[0149] Finally, in step S740, the apparatus for measuring optical characteristics may calculate ghosting levels on the basis of the coordinates of the plurality of patterns and the coordinates of the plurality of ghost patterns.

[0150] In this case, the apparatus for measuring optical characteristics may calculate a ghosting level from the gap between an original pattern and a corresponding ghost pattern.

[0151] In more detail, the apparatus for measuring optical characteristics may calculate a ghosting level, using Formula 8.

[00015]$\begin{array}{cc}\mathrm{Ghost}=\frac{\left(\underset{i=1}{\overset{3}{.Math.}}\underset{j=1}{\overset{3}{.Math.}}\sqrt{\begin{array}{c}{\left(x_{\mathrm{ij}}-x_{\mathrm{Gij}}\right)}^2+\\ {\left(y_{\mathrm{ij}}-y_{\mathrm{Gij}}\right)}^2+{\left(z_{\mathrm{ij}}-z_{\mathrm{Gij}}\right)}^2\end{array}}\right)}{\left(9\right)}& \left[\mathrm{Formula}8\right]\end{array}$

[0152] where Ghost is a ghosting level, x.sub.ij, y.sub.ij, and z.sub.ij are the x, y, and z coordinates of a horizontal i-th (i=1, 2, 3) and vertical j-th (j=1, 2, 3) pattern, and x.sub.Gij, y.sub.Gij, and z.sub.Gij are the x, y, and z coordinates of a horizontal i-th and vertical j-th ghost pattern.

[0153] FIG. 8 is a block diagram showing an apparatus for measuring optical characteristics of an augmented reality device according to an exemplary embodiment of the present invention.

[0154] Referring to FIG. 8, an apparatus 800 for measuring optical characteristics of an augmented reality device according to an exemplary embodiment of the present invention includes a photographing unit 810, an acquiring unit 820, and a calculating unit 830.

[0155] The photographing unit 810 takes a test image including a plurality of patterns that is output on a virtual plane by an augmented reality device, using at least one camera disposed around a predetermined measurement reference position.

[0156] The acquiring unit 820 acquires field of view information including information about the field of view of the at least one camera, and photographing system information including information about the arrangement of the at least one camera.

[0157] Finally, the calculating unit 830 calculates the coordinates of a plurality of patterns with respect to the measurement reference position on the basis of a plurality of captured images taken by the at least one camera, field of view information, and photographing system information.

[0158] In another exemplary embodiment, the at least one camera is a central camera positioned at the measurement reference position, and a left camera and a right camera symmetrically positioned with the measurement reference position therebetween. When a plurality of patterns is horizontally and vertically arranged in one test image, the calculating unit 830 may calculate the coordinates of a plurality of patterns, using the number of horizontal pixels of a plurality of captured images, the coordinates of a plurality of patterns in the plurality of captured images, the field of view of at least one camera included in field of view information, and the distance between the left camera and the right camera included in the photographing system information.

[0159] In another exemplary embodiment, the calculating unit 830 may calculate the coordinates of a plurality of patterns, using Formula 9.

[00016]$\begin{array}{cc}{z}_{\mathrm{ij}}=\frac{\alpha }{2.Math.\tan \frac{\theta }{2}}.Math.\frac{M}{\left(m_{ij}^L-m_{ij}^R\right)}{x}_{ij}=z_{ij}.Math.\tan \frac{\theta }{2}\left(2.Math.\frac{m_{\mathrm{ij}}^C}{M}-1\right)y_{ij}=z_{ij}.Math.\tan \frac{\theta }{2}\left(2.Math.\frac{n_{ij}^C}{M}-1\right)& \left[\mathrm{Formula}9\right]\end{array}$

[0160] where x.sub.ij, y.sub.ij, and z.sub.ij are x-axial, y-axial, and z-axial coordinates of the horizontal i-th and vertical j-th pattern with respect to the measurement reference position, α is the distance between the left camera and the right camera, M is the number of horizontal pixels of a plurality of captured images, θ is the field of view of at least one camera, m.sup.L.sub.ij is the horizontal coordinate of the horizontal i-th and vertical j-th pattern in the captured image of the left camera, m.sup.R.sub.ij is the horizontal coordinate of the horizontal i-th and vertical j-th pattern in the captured image of the right camera, and m.sup.C.sub.ij is the horizontal coordinate of the horizontal i-th and vertical j-th pattern in the captured image of the central camera.

[0161] In another exemplary embodiment, the calculating unit 830 may further calculate a virtual image distance between a measurement reference position and a virtual plane, using the coordinates of the measurement reference position and the coordinates of at least one of a plurality of patterns on the virtual plane.

[0162] In another exemplary embodiment, the calculating unit 830 may calculate a virtual image distance, using Formula 10.

D.sub.VI=√{square root over (x.sub.22.sup.2+y.sub.22.sup.2+z.sub.22.sup.2)} [Formula 10]

[0163] where D.sub.VI is a virtual image distance, and x.sub.22, y.sub.22, and z.sub.22 are the coordinates of one of a plurality of patterns.

[0164] In another exemplary embodiment, the calculating unit 830 may further calculate a look down/up angle from a measurement reference position to a virtual plane, using the coordinates of the measurement reference position and the coordinates of at least one of a plurality of patterns on the virtual plane.

[0165] In another exemplary embodiment, the calculating unit 830 may calculate look down/up angle, using Formula 11.

[00017]$\begin{array}{cc}{\theta }_{down/up}={\cos }^{-1}\frac{\sqrt{x_{22}^2+z_{22}^2}}{\sqrt{x_{22}^2+y_{22}^2+z_{22}^2}}& \left[\mathrm{Formula}11\right]\end{array}$

[0166] where θ.sub.down/up is a look down/up angle, and x.sub.22, y.sub.22, and z.sub.22 are the coordinates of one of a plurality of patterns.

[0167] In another exemplary embodiment, the calculating unit 830 may further calculate the horizontal field of view of a measurement reference position, using the coordinates of the measurement reference position and the coordinates of two patterns positioned at both horizontal ends of a plurality of patterns on a virtual plane.

[0168] In another exemplary embodiment, the calculating unit 830 may calculate a horizontal field of view, using Formula 12.

[00018]$\begin{array}{cc}{\theta }_{FOV}^H={\cos }^{-1}\frac{{.Math.\stackrel{\_}{P_{21}O}.Math.}^2+{.Math.\stackrel{\_}{P_{23}O}.Math.}^2-{.Math.\stackrel{\_}{P_{21}{P}_{23}}.Math.}^2}{2.Math..Math.\stackrel{\_}{P_{21}O}.Math..Math.\stackrel{\_}{P_{23}O}.Math.}& \left[\mathrm{Formula}12\right]\end{array}$

[0169] where θ.sup.H.sub.FOV is a horizontal field of view, O is the coordinate of a measurement reference position, and P.sub.21 and P.sub.23 are coordinates of two patterns positioned at both horizontal ends.

[0170] In another exemplary embodiment, the calculating unit 830 may further calculate the virtual field of view of a measurement reference position, using the coordinates of the measurement reference position and the coordinates of two patterns positioned at both virtual ends of a plurality of patterns on a virtual plane.

[0171] In another exemplary embodiment, the calculating unit 830 may calculate a virtual field of view, using Formula 13.

[00019]$\begin{array}{cc}{\theta }_{FOV}^V={\cos }^{-1}\frac{{.Math.\stackrel{\_}{P_{12}O}.Math.}^2+{.Math.\stackrel{\_}{P_{32}O}.Math.}^2-{.Math.\stackrel{\_}{P_{12}{P}_{32}}.Math.}^2}{2.Math..Math.\stackrel{\_}{P_{12}O}.Math..Math.\stackrel{\_}{P_{32}O}.Math.}& \left[\mathrm{Formula}13\right]\end{array}$

[0172] where θ.sup.V.sub.FOV is a vertical field of view, O is the coordinate of a measurement reference position, and P.sub.12 and P.sub.32 are coordinates of two patterns positioned at both vertical ends.

[0173] In another exemplary embodiment, the calculating unit 830 may further calculate a static distortion for each of three axes with respect to a measurement reference position on the basis of the coordinates of a plurality of patterns on a virtual plane.

[0174] In another exemplary embodiment, the calculating unit 830 may further calculate the coordinates of a plurality of ghost patterns corresponding to the coordinates of a plurality of patterns, respectively, on the basis of a plurality of captured images, field of view information, and photographing system information, and may further calculate ghosting levels on the basis of the coordinates of the plurality of patterns and the coordinates of the plurality of ghost patterns.

[0175] Meanwhile, the exemplary embodiments of the present invention described above may be written as programs that can be executed in a computer and may be implemented in a common digital computer that executes the programs using a computer-readable recording medium.

[0176] The computer-readable recording medium includes a magnetic storage medium (e.g., a ROM, a floppy disk, and a hard disk) and an optical reading medium (e.g., a CD-ROM and a DVD).

[0177] Preferred exemplary embodiments of the present invention were described. It would be understood by those skilled in the art that the present invention may be modified without departing from the scope of the present invention. Therefore, the disclosed exemplary embodiments should be considered in terms of explaining, not limiting. The scope of the present invention is not shown in the above description, but claims, and all differences within an equivalent range should be construed as being included in the present invention.