Image correction due to deformation of components of viewing device

Abstract

To enable image correction for deformation of components of a viewing device.SOLUTION: A display assembly displays a virtual object at a select location, and an eye viewing the virtual object has an expected gaze direction. Deformation of the display assembly is detected. The deformation causes the virtual object to be viewable at an altered location, and the eye has an altered gaze direction. The virtual object may be displayed at a corrected location, and the eye viewing the virtual object at the corrected location has a corrected gaze direction that is moved closer to the expected gaze direction than the altered gaze direction.SELECTED DRAWING: Figure 2B

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims priority from U.S. Provisional Patent Application No. 62 / 643,672, filed on Mar. 15, 2018, which is hereby incorporated by reference in its entirety.

[0002] 1) Field of the Invention The present invention generally relates to visual devices and methods for displaying rendered content, and more particularly to detecting and correcting deformations of components of visual devices.

Background Art

[0003] 2) Discussion of Related Fields Visual devices that provide rendered images have become popular for computing, entertainment, and other purposes. A visual device is typically a wearable device with a display for rendering an image, and can include various features such as the ability to show a user a three - dimensional image, to show a user a rendering within a real - world environment whether or not the location within the real - world environment is fixed, and to display a video or other moving rendering to the user.

[0004] The viewing device has various components that deform over time due to their use. When these components deform, the virtual objects being rendered may not be in their original locations, even when the viewing device was still new. For example, a background application may display virtual objects at a location fixed relative to the viewing device or at a location fixed relative to real-world objects surrounding the user. In some cases, the viewing device may have a see-through display so that the user can see real-world objects and perceive the rendered objects at locations fixed relative to the real-world objects. For example, the user may perceive a rendered coffee cup on a real-world table. When the components of the viewing device deform, the coffee cup may no longer be rendered on the table and may instead float at a distance above the table. The coffee cup is thus not presented to the user in a manner that conforms to reality. Additionally, when the coffee cup is used as an interface element for the user to interact with a background application, there may be a mismatch between the location where the background application expects the coffee cup to be and the location where the user interacts with the coffee cup. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEM

[0005] The present invention provides a viewing device for displaying rendered content, including a display assembly configured to display virtual objects at selected locations on the display assembly, wherein the eyes viewing the virtual objects have an expected gaze direction, and a deformation detection system connected to the display assembly and configured to detect the measured gaze direction of the eyes viewing the virtual objects on the display assembly and calculate a deformation of the display assembly based on the measured gaze direction being a modified gaze direction different from the expected gaze direction.

[0006] The present invention also provides a method for displaying rendered content, including steps of: using a display assembly to display a virtual object at a selected location on the display assembly, where the eye viewing the virtual object has an expected gaze direction; detecting a deformation of the display assembly, where the deformation makes the virtual object visible at a modified location and the eye has a modified gaze direction. For example, the present application provides the following items. (Item 1) A viewing device for displaying rendered content, comprising: A display assembly configured to display a virtual object at a selected location on the display assembly, where the eye viewing the virtual object has an expected gaze direction; A deformation detection system connected to the display assembly, the deformation detection system detecting a measured gaze direction of the eye viewing the virtual object on the display assembly and calculating a deformation of the display assembly based on the measured gaze direction being a modified gaze direction different from the expected gaze direction. A viewing device comprising the above. (Item 2) The system according to Item 1, further comprising a correction system connected to the deformation detection system for displaying the virtual object at a corrected location, where the measured gaze direction of the eye viewing the virtual object at the corrected location is a corrected gaze direction, and the difference between the expected gaze direction and the corrected gaze direction is less than the difference between the expected gaze direction and the modified gaze direction. (Item 3) The display assembly includes an optical display, and the deformation is a deformation of the optical display, the system according to item 1. (Item 4) The optical display is deformed in the display deformation direction, and the modified line-of-sight direction is moved with respect to the expected line-of-sight direction in the display deformation direction, the system according to item 3. (Item 5) The optical display is transparent, and the virtual object is visible to the eye at a location on the side of the optical display facing the eye, the system according to item 4. (Item 6) The deformation detection system An eye-tracking camera configured to capture light reflected from the eye, A line-of-sight angle calculation module, the line-of-sight angle calculation module being configured to calculate the measured line-of-sight direction of the eye based on the light captured by the eye-tracking camera, a line-of-sight angle calculation module including, the system according to item 3. (Item 7) The measured line-of-sight direction calculated by the line-of-sight angle calculation module is the modified line-of-sight direction caused by deformation of at least one of the eye-tracking camera and the optical display, the system according to item 6. (Item 8) The difference between the expected line-of-sight direction and the modified line-of-sight direction is in a first direction, the change in the measured line-of-sight direction due to deformation of the eye-tracking camera is in a second direction, the first and second directions are less than 90 degrees relative to each other, and further, A correction system connected to the deformation detection system for displaying the virtual object at a corrected location using the display assembly, the eye viewing the virtual object at the corrected location having a corrected line-of-sight direction that moves from the modified line-of-sight direction toward the expected line-of-sight direction, the system according to item 7. (Item 9) The change from the expected gaze direction to the modified gaze direction is in a first direction, the change in the measured gaze direction due to the deformation of the eye-tracking camera is in a second direction, and the first and second directions are separated by more than 90 degrees with respect to each other. The system according to item 7. (Item 10) The system according to item 9, further comprising a correction system connected to the deformation detection system for displaying the virtual object without moving the virtual object from the modified location using the display assembly. (Item 11) The system according to item 9, further comprising a correction system connected to the deformation detection system for displaying the virtual object at a corrected location using the display assembly, and the eye viewing the virtual object at the corrected location has a measured gaze direction that is a corrected gaze direction, and the corrected gaze direction is moved from the modified gaze direction toward the expected gaze direction. (Item 12) A reference system for detecting a change in the measured gaze direction due to the deformation of the eye-tracking camera, A correction calculation unit, which determines the change in the measured gaze direction due to the deformation of the display assembly by subtracting the change in the measured gaze direction due to the deformation of the eye-tracking camera from the change in the gaze angle detected by the deformation detection system. A correction calculation unit, A correction system connected to the deformation detection system for displaying the virtual object at a corrected location using the display assembly, and the eye viewing the virtual object at the corrected location has a corrected gaze direction that is moved in a direction opposite to the change in the gaze angle due to the deformation of the display assembly. A correction system The system according to item 11, further comprising. (Item 13) The deformation detection system a statistical system configured to receive and analyze a plurality of measured fixation direction measurement values, a fixation angle calculation unit that calculates a plurality of fixation directions, each fixation direction being related to an individual measurement value, the fixation angle calculation unit, a correction calculation unit that determines the modified fixation direction based on a plurality of actual fixation direction measurement values The system according to item 1, comprising: (Item 14) The deformation detection system according to item 1, further comprising an attention generation unit configured to modify the display of the virtual object and attract the user's attention to the virtual object before detecting the deformation. (Item 15) The system according to item 14, wherein the attention generation unit is configured to attract the user's attention to the virtual object by changing the color of the virtual object. (Item 16) The system according to item 14, wherein the attention generation unit is configured to attract the user's attention to the virtual object by reducing the size of the virtual object. (Item 17) A method of displaying rendered content, comprising: displaying a virtual object at a selected location on the display assembly using the display assembly, wherein the eye that visually recognizes the virtual object has an expected fixation direction; detecting a deformation of the display assembly, the deformation making the virtual object visible at a modified location, and the eye having a modified fixation direction The method comprising: (Item 18) The method of item 17, further comprising displaying the virtual object at a corrected location using a display assembly, wherein the eye viewing the virtual object at the corrected location is moved from the modified gaze direction toward the expected gaze direction and has a corrected gaze direction.

Brief Description of the Drawings

[0007] The present invention will be further described using examples.

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[0024] FIG. 1 of the accompanying drawings illustrates a visual device 20 according to an embodiment of the present invention for use in displaying rendered content to a user's eye 22. The visual device 20 includes a display assembly 24, a deformation detection system 26, a user input device 28, and a correction system 30.

[0025] The display assembly 24 includes a video data receiver 32, a projector 34, and an optical display 36 that are directly or indirectly connected to each other. The display assembly 24 includes a structure (not shown) that can be fixed to the user's head with the optical display 36 in front of the user's eye 22. The optical display 36 is a transparent component that allows the eye 22 to see real-world objects behind the optical display 36 and that can simultaneously project a virtual image to the user such that light associated with real and virtual objects is visible to the user.

[0026] The video data receiver 32 is connected to, or connectable to, a video data channel that carries pixel color and intensity values. The projector 34 has a laser and a scanning device that are capable of creating a two-dimensional pattern based on the video data. The optical display 36 is located at a position for the laser of the projector 34 to couple laser light into the optical display 36. The laser light then propagates through the optical display 36 and exits the optical display 36 towards the eye 22 through the pupil of the optical display 36. The eye 22 thus receives light from real-world objects behind the optical display 36 and light generated by the projector 34. An augmented reality view is then created on the retina 38 of the eye 22, and the augmented reality view includes light from the real-world scene visible to the user through the optical display 36 that is combined with the light created by the projector 34 representing virtual content.

[0027] The deformation detection system 26 includes an attention generation unit 40, an input trigger 42, an eye tracking camera 44, a fixation angle calculation module 46, a statistical system 48, and a correction calculation unit 50.

[0028] The attention generation unit 40 is connected to the video data receiver 32. The attention generation unit 40 is configured to provide override functionality for the video data receiver 32. The attention generation unit 40 may, for example, insert a virtual object into the data stream received by the video data receiver 32, change the color of the virtual object, and / or reduce the size of the virtual object for the purpose of directing the fixation angle of the eye 22 towards the virtual object and focusing on the virtual object. Although the attention generation unit 40 is described, virtual content that can be used as a basis for calibrating the augmented reality system may generally be provided by a rendering system or module.

[0029] The input trigger 42 is connected to the user input device 28 and detects user input through the user input device 28. The user input device 28 may be, for example, one or more of a joystick, a wand, a camera that tracks a user's body part, a button, a touchpad, a sensor-equipped glove, a mouse, a keyboard, etc. The user input device 28 provides the input to the input trigger 42.

[0030] The eye tracking camera 44 is mounted on the display assembly 24 at a position for capturing an image of the eye 22. In some embodiments, one or more cameras per eye are used to image the user's eyes. Alternatively, a single camera having an angle wide enough to capture an image including both of the user's eyes may be used.

[0031] The fixation angle calculation module 46 is connected to the eye tracking camera 44 and the input trigger 42. The fixation angle calculation module 46 calculates the fixation angle of the eye 22 based on the image captured by the eye tracking camera 44. The fixation angle calculation module 46 is connected to the input trigger 42 and is activated by the input trigger 42 such that the fixation angle is calculated by the fixation angle calculation module 46 when user input is detected. Although the system is described using the calculated fixation angle, any other eye fixation orientation characteristic such as, for example, a fixation vector, fixation coordinates, visual axis orientation, or corneal center location may also be used. Additionally, fixation data from the left and right eyes may be used in combination to gather information about where the user's eyes are focused.

[0032] The statistical system 48 is connected to the gaze angle calculation module 46 and receives a large number of gaze angle calculation measurements. The statistical system 48 records the gaze angles received from the gaze angle calculation module 46 each time the input trigger 42 activates the gaze angle calculation module 46. The statistical system 48 thus collects several gaze angles over a certain time period. The statistical system 48 then calculates statistically relevant gaze angles, for example, the median gaze angle from the gaze angles recorded by the statistical system 48. A representative gaze angle may be selected or calculated and used in comparison with the expected gaze angle associated with the display of virtual content. If the representative gaze angle is substantially different from the expected gaze angle, it is concluded that a distortion within the system is occurring.

[0033] The correction calculation unit 50 is connected to the statistical system 48. The correction calculation unit 50 calculates the desired correction at the location of the rendered virtual object created or modified by the attention generation unit 40.

[0034] The correction system 30 is connected to the correction calculation unit 50. The correction system 30 receives correction data from the correction calculation unit 50. The video data receiver 32 is connected to the correction system 30. The correction system 30 corrects the location of the virtual object created or modified by the attention generation unit 40. The correction system 30 also corrects the locations of all other objects in the video stream by the same amount and in the same direction as the location of the virtual object generated and modified by the attention generation unit 40 is corrected.

[0035] In use, the user attaches the viewing device 20 to their head with the optical display 36 facing the front of the eye 22. The user can then view real-world objects through the transmissive optical display 36 and simultaneously view the rendered virtual content.

[0036] The video data receiver 32 receives video data from a background application. The background application may be, for example, a video application for displaying videos, games, web browsers, menus, launchers, 2D content, 3D content, or any other type of virtual content. The video data includes data representing frames of an image received at a video data rate. The video data includes pixels with intensity and color values. The video data receiver 32 provides the video data to the projector 34. The projector 34 creates a 2D pattern for each frame. The pattern includes laser light bundles, and each bundle represents an individual pixel, and its intensity and color may be modulated. The projector 34 couples the pattern into the optical display 36 either directly or indirectly through a lens, mirror, grating, or the like. The pattern passes through the optical display 36 and exits the optical display 36 towards the eye 22. The light beam 54 represents the light transmitted from the optical display 36 towards the eye 22. However, it should be understood that many light beams representing virtual objects are projected from the optical display 36 such that the image received by the retina 38 is similar to the pattern created by the projector 34. In some embodiments, the virtual object may be perceived by the user as being three-dimensional due to one or more wavefront shaping techniques applied to the light representing the virtual object. In embodiments where the moving image continuously changes with each frame of the data provided by the video data receiver 32 to the projector 34, it can be seen by the user.

[0037] The video data received by the video data receiver 32 includes data representing one or more objects to be displayed on the retina 38 of the eye 22. The virtual objects represented within the data received by the video data receiver 32 may in fact be displayed on the optical display 36. However, such virtual objects may not be visible or easily distinguishable on the surface of the optical display 36 due to several factors, including that the optical display 36 is a see-through display and / or the optical display 36 serves primarily as a waveguide for directing light between the projector 34 and the eye 22. The video data provided by the video data receiver 32 to the projector 34 includes data representing the objects, even if the virtual objects may not be visible on the surface of the optical display 36. For purposes of discussion, it will be assumed that a virtual object or a plurality of virtual objects are visible on the surface of the optical display 36. However, for ease of illustration, it should be understood that a plurality of objects are shown on the surface of the optical display 36. The present invention primarily addresses the same calibration methodology regardless of whether the objects are actually visible or not visible on the surface of the optical display 36.

[0038] During normal operation of the visual recognition device, the attention generation unit 40 does not provide override functionality for the normal operation of the video data receiver 32. All video data is presented to the user at a certain video refresh rate without any interference from the deformation detection system 26. The deformation detection system 26 overrides the normal functionality of the video data receiver 32 only a few times a day (for example, 50 to 100 times of continuous use per day) and performs measurements while the video data receiver 32 continues without interruption for the rest of the time. The user input device 28 and the eye tracking camera 44 are connected to the background application. During normal operation of the video data receiver 32, the user may use the user input device 28 to provide commands to the background application or otherwise interact with the virtual content rendered on the optical display 36 while one or more eye tracking cameras 44 continue to monitor the eyes 22. The user may, for example, use the user input device 28 to interact with the virtual objects displayed to the user via the optical display 36 while the background application relies on the eye tracking camera 44 to determine when the user is looking at the virtual objects.

[0039] After factory calibration of the viewing device 20, there is little or no deformation of the display assembly 24. An object displayed using the optical display 36 is in its expected location relative to the viewing angle of the eye 22. Over time with use of the viewing device 20, components of the viewing device 20 that include or are connected to the display assembly 24 begin to deform. The deformation can manifest in deformation of the optical display 36, deformation of the hinge, and deformation of the materials used in the structure that mounts the viewing device 20 to the user's head. The deformation is typically due to small or large stresses applied to the components of the display assembly 24 and the combination of materials of the components of the display assembly 24. The stresses can be generated, for example, when wiring connected to the optical display 36 pulls on the optical display 36, when the user fits the viewing device 20 to or removes it from their head, and when the user operates a hinge, spring, or other dynamic component for the purpose of unpacking or storing the viewing device 20. The material properties of the components of the display assembly 24 can be subject to fatigue when the stresses are repeated, and plastic materials are known to undergo "creep" when subjected to stress over time. Some of the materials of the viewing device 20 can also be subject to thermal loading, and such temperature changes can contribute to the deformation of one or more components. As a result of the deformation, the actual location where the virtual objects appear to the user on the deformed viewing device 20 is not the intended rendering location of those virtual objects. Consequently, the actual gaze of the user will be different from the gaze that would be expected if the user were looking at virtual content rendered at its intended rendering location. In addition, the deformation is continuous, and thus it is expected that the rendering location of the virtual objects as perceived by the user will continue to move over time relative to the intended rendering location. The display assembly 24 initially displays the virtual object at the selected location, and the eye 22 has the expected gaze direction.A modification of the display assembly 24 renders the virtual object visible at the modified location, and the eye 22 has a modified line of sight.

[0040] One or more components of the deformation detection system 26 may be functionally and structurally connected to the display assembly 24 to detect deformation of the display assembly. The correction system 30 is connected to the deformation detection system 26. The correction system 30 uses the display assembly 24 to display the virtual object at the corrected location. When the virtual object is displayed at the corrected location, the eye 22 viewing the virtual object at the corrected location has a corrected line of sight that is moved closer to the expected line of sight than the modified line of sight. The deformation detection system 26 provides override or extended functionality relative to the normal operation of the viewing device 20 described above. The deformation detection system 26 is intermittently activated, for example, 10 to 20 times per hour during continuous operation. Additionally, the deformation detection system 26 is activated for only a few seconds, for example, 3 to 7 seconds, which is about as long as is necessary to make measurements and adjustments. The viewing device 20 operates normally for the remainder of the time.

[0041] The function of the deformation detection system 26 is initiated by the user input device 28 activating the attention generation unit 40 while being connected to the input trigger 42 and the eye tracking camera 44 continues to monitor the eye 22. What is mainly required is that the user interacts with the rendered object received by the video data receiver 32 from the background application, which is small enough to minimize the fixation vector error. The attention generation unit 40 may also modify the color of the virtual object or reduce its size to help draw the user's attention and draw the eye 22 to the small point where the virtual object is located. The video data receiver 32 provides data representing the virtual object to the projector 34. The projector 34 then generates light and projects the light representing the virtual object towards the optical display 36 for visual recognition by the user.

[0042] The virtual object installed or modified by the attention generation unit 40 is of the type that requires the user to interact with the rendered virtual object using the user input device 28. Such virtual objects may be, for example, play buttons, targets, application launch icons, etc. When the user uses the user input device 28 to interact with the rendered virtual object, it is assumed that the user's eye 22 is looking at the rendered virtual object on the optical display 36. The eye tracking camera 44 captures an image of the eye 22 and provides the image data to the fixation angle calculation module 46. The user input device 28 activates the input trigger 42, which commands the fixation angle calculation module 46 to calculate the fixation angle of the eye 22 using the data received from the eye tracking camera 44. The fixation angle calculated by the fixation angle calculation module 46 represents the actual location of the rendered virtual object on the optical display 36 as perceived by the user.

[0043] The fixation angle calculation module 46 provides the fixation angle to the statistical system 48. The statistical system 48 stores the fixation angle. When the deformation detection system 26 is activated for the second time, the process is repeated and the statistical system 48 stores the second fixation angle. The process is repeated until the statistical system 48 stores enough fixation angles to enable the statistical system 48 to calculate a modified fixation angle that is statistically relevant. The statistical system 48 may calculate, for example, a representative value, an average value, or a median fixation angle from the collected fixation angles. The statistical system may calculate a statistically relevant fixation angle from all measurements, but it is preferred that the statistical system uses only fixation angles that are outside a predetermined error range (e.g., 90 arc minutes) as data points for calculating the statistically relevant fixation angle. Alternatively, in some embodiments, instead of accumulating multiple measurements to calculate a statistically determined fixation angle before performing the incremental correction, each measured fixation angle that is determined to be outside the tolerance of the expected fixation angle may result in an incremental correction to the rendering location of the virtual content.

[0044] The statistical system 48 provides the modified fixation angle to the correction calculation unit 50. The correction calculation unit 50 determines the amount of correction required at the fixation angle to return the fixation angle from the modified fixation angle to the expected fixation angle. The correction calculation unit 50 calculates both the direction and amount of the required correction and then calculates the actual correction, which is a very small part of the required correction. The correction calculation unit 50 then provides the actual correction to the correction system 30. The correction system 30 provides the correction to the video data receiver 32. The video data receiver 32 then moves the virtual object and all other objects generated by the attention generation unit 40 according to the direction and magnitude of the actual correction received from the correction system 30.

[0045] The statistical system 48 may require a large number of measurements, e.g., 50 to 100 measurements, before providing the corrected viewing angle to the correction calculation unit 50. Additionally, any corrections made are a very small part of the actual change in the viewing angle due to the deformation of the display assembly 24. Cumulative correction is thus a slow process. As an example, only a single correction may be made during 8 hours of continuous operation per day, and it may take several days or weeks for the viewing angle to be corrected within the acceptable range of the expected viewing angle. Alternatively, several small corrections may be made during the use of the device. The number of corrections may depend on the number of times the user interacts with virtual content that is considered reliable for viewing angle calculation and rendering location calibration. Such a slow process allows for recalculation in case of errors and enables the continued acceleration and deceleration of the deformation of the display assembly 24 with little risk of over-correcting the required corrections that need to be made assuming the continued deformation of the display assembly 24.

[0046] In FIG. 2A, the non-deformed shape 60 represents the optical display 36 before deformation. A rendered object 62 is placed within the optical display 36 to attract the user's attention. When the user views the rendered object 62, an actual gaze vector 64 can be defined. The actual gaze vector 64 is the direction or axis along which the eye 22 is directed for the purpose of visually recognizing the virtual object. The actual gaze vector extends from the center point 22 of the eye 22 through the center of the pupil of the eye. To calculate the actual gaze vector 64, one approach would be to first calculate the actual center point 22 of the eye 22. It may also be possible to calculate the actual gaze vector 64 by using other anatomical information of the eye for that purpose instead of calculating the actual center point 22 of the eye 22. The expected gaze vector 64 extends through the optical display 36, and the user perceives the rendered object 62 as an extended object 68. The extended object 68 is located within a plane represented by the non-deformed shape 70. Since the plane of the non-deformed shape 70 is farther from the plane of the optical display 36, the user perceives the extended object 68 as larger than the rendered object 62 and the field defined by the non-deformed shape 70 as larger than the field defined by the non-deformed shape 60. The user also perceives a table 72. The perception the user has is of the table 72 being extended using the rendered virtual content represented in FIG. 2A by the extended object 68.

[0047] A plurality of infrared light-emitting diodes (LEDs) 74 may be included within the eye-tracking system. Each LED 74 transmits infrared light that forms an individual infrared spot (“glint”) 76 on the surface of the eye 22. Reference numeral 78 represents infrared light that reflects from the spot 76 toward the eye-tracking camera 44. The eye-tracking camera 44 captures all locations of the spots created by the LEDs 74 on the surface of the eye 22. The location of the spots 76 is used by the fixation angle calculation module 46 to calculate the fixation angle or fixation vector of the eye 22. In some embodiments, the eye-tracking camera may also capture the location of the pupil. The pupil location data can be used in combination with the infrared glints to determine the eye position. The fixation angle or fixation vector may be calculated or otherwise determined based on the eye position information.

[0048] The expected fixation vector 64 is shown in FIG. 2A to pass through the centers of the rendered object 62 and the extended object 68. Reference numeral 82 represents light reflected from the eye 22 that is captured by the eye-tracking camera 44. In some embodiments, the eye-tracking camera 44 thus captures the orientation of the eye and the location of the pupil 80. The fixation angle calculation module 46 calculates the actual fixation vector (that matches the expected fixation vector 64 in FIG. 2A) using at least the location of the interactive rendered virtual content. In some embodiments, the location of the eye 22 relative to the optical display 36 may also be used.

[0049] It may not always be necessary to perform measurements for the purpose of determining the pre-deformation viewing angle. For example, when the viewing device 20 is new, the display assembly 24 is not deformed, and it can be assumed that the viewing angle of the eye 22 is such that it is represented by the expected viewing vector 64 when the rendered object 62 is positioned as shown. The rendered object 62 can thus be positioned as shown, and the expected initial viewing vector 64 can be determined without any additional measurements. The expected viewing angle and the actual viewing angle will vary based on the location of the rendered content. An "initial" or "pre-deformation" viewing angle can be calculated, but the expected viewing vector can be assumed from the background application or previous calculations. The difference between the assumed expected viewing angle and the newly calculated actual viewing angle can then be calculated.

[0050] In FIG. 2B, the shape 86 represents a deformation of the optical display 36. The deformation of the optical display 36 is represented by the difference in the shape 86 when compared to the undeformed shape 60. The rendered object 62 is still rendered at the same (x, y) location on the display, but the deformation of the display to the user causes the user to perceive the content at a location different from the intended location. Due to the deformation, the rendered object 62 is no longer at the location shown in FIG. 2A, but has moved only by the distance and direction as represented by the vector 88. The rendered object 62 is thus moving in a direction that is the result of the deformation of the optical display 36 in the area of the rendered object 62. A modified gaze vector 90 is defined between the eye 22 and the rendered object 62. The user views the rendered object 62 as an extended object 68 in the plane as represented by the shape 92. The shape 92 is deformed relative to the undeformed shape 70 in a manner similar to the deformation between the shape 86 and the undeformed shape 60.

[0051] When the user looks at the extended object 68, the actual gaze vector 90 passes from the eye 22 to the location of the extended object 68 within the deformed shape 92. In this embodiment, the actual gaze vector 90 is different from the expected gaze vector 64. The eye tracking camera 44 continues to capture eye location information based on the pupil location and / or the glint reflection pattern in the image such that the gaze angle calculation module 46 can calculate the actual gaze vector 90, compare it with the expected gaze vector 64, and infer whether a display assembly deformation has occurred.

[0052] FIG. 3A illustrates how the location of the rendered object 62 is corrected. The projector 34 projects image light 94 associated with the virtual image or object at a predetermined angle toward the optical display 36. The image light 94 may encounter one or more diffractive optical elements such as an internal coupling grating 95, an orthogonal pupil expander 97, and an exit pupil expander 99 disposed within or on the waveguide 101 as part of the optical display 36. As the image light 94 propagates through the waveguide 101, the diffractive optical elements redirect the light in different ways, ultimately causing the image light 94 to exit the waveguide toward the user's eye 22 through the exit pupil expander 99. The user's eye 22 can focus the image light 94 at a location on the retina in order for the user to perceive the rendered object 62.

[0053] Referring to FIGS. 3B and 3C, two examples of an image projected as image light 94 are shown. In FIG. 3B, virtual content object 115 is shown at the center of image 94a. As image 94a is projected towards the non-deformed optical display 36 and travels through its components, the user will see virtual content object 115 at the center of the field of view. However, if image 94a is projected towards a deformed display, virtual content object 115 may be perceived by the user as shifted to the right, for example, such that it is no longer at the center of the field of view. To correct for the shift detected by comparing the expected and actual fixation vectors caused by the deformation, image 94b may be projected instead of image 94a. In image 94b, virtual content object 115 is shifted towards the left of the image such that when the light exits the display deformed in the rightward shift, the right shift of the display cancels out the left shift of the content and virtual content object 115 appears to the user to be at the center of the field of view. Pixel shifting may be accomplished by using LEDs or other similar light sources to illuminate different pixels of a spatial light modulator (SLM) within projector 34. In such an adjustment method, it may be useful to convert the actual and expected fixation angles or fixation vectors into the display coordinate system. For example, the system may expect the user's fixation to be centered on a pixel at coordinates (x1,y1), but finds that the user's fixation is actually centered on a pixel at coordinates (x2,y2) in the display coordinate system. In such a method, the pixel shift can be adjusted by an amount equal to and opposite to the difference between the expected viewing coordinates and the actual viewing coordinates as determined by the user's fixation vector. Alternative means for adjusting the rendering location of the virtual content may also be used.

[0054] In some embodiments, as shown in FIG. 3D, the correction may be performed by adjusting the projector 34 itself. For a complete correction, the rendering location of the rendered object 62 needs to move from location 100 to the corrected location 104 in the direction represented by vector 102. For a complete correction, the projector 34 may insert the light 106 into the diffractive optical element of the optical display 36 at an adjusted angle such that the rendered object 62 is visible closer to the intended location within the field of view. The user will perceive the rendered object 62 as if it has moved from location 100 along vector 102 towards location 104. However, a complete correction is not performed. Instead, the rendered object 62 is moved only a small portion of the distance between location 100 and location 104 along the direction represented by vector 102. The projector 34, therefore, inserts the light at an angle that is slightly steeper than the image light 94 but not as steep as the light 106 for the purpose of performing a partial correction.

[0055] Figure 4 illustrates potential fixation vector errors 120 and 122 in two user interaction events. Anatomically, the eye is continuously moving when it is focused on a static image such as the enlarged object 68. Natural eye movement typically results in an error or deviation of about 60 arc minutes from the central fixation vector corresponding to the direct path from a selected anatomical marker of the eye, e.g., the center point 66 of the eye 22, to the enlarged object 68. In some embodiments, the fixation vector may be defined as the direct path from the center of the eye's cornea to the enlarged object 68 or as the extension of the eye's visual axis. When the user is looking at the enlarged object 68, a fixation vector within the expected fixation vector range having a 60 arc minute radius from the fixation vector 90 may be considered to be directed towards the location of the enlarged object 68. The fixation angle calculation module 46 of FIG. 1 may also have some error regarding a given eye size, shape, etc., and such additional error can be added, for example, to the radius of the expected fixation vector range of about 30 arc minutes. When the user is looking at the enlarged object 68 and it is determined that the calculated fixation vector is within a 90 arc minute radius of the fixation vector 90, the system is considered to be adequately calibrated.

[0056] One problem is that the relatively large 90-minute angular radius of the error in the fixation vector makes it difficult to determine the exact location of the perceived position of the extended object 68. To account for potential errors, the statistical system 48 of FIG. 1 may collect multiple data points to discover trends. The trends in the determined fixation vectors are accumulated to discover the likely locations of the perceived positions of the extended object 68 as displayed by a system with a certain amount of distortion. Since the amount of positional mismatch that is noise due to eye movement or algorithmic errors and the amount due to the actual distortion of the display assembly 24 of FIG. 1 are still uncertain, a complete correction of the fixation direction is not performed. As an example, the correction increment can be between 0.01 and 0.5 minute of arc, for example, 0.1 minute of arc. Alternatively, the amount of the correction increment can be based on the amount of detected distortion, with larger distortions potentially requiring larger increments. As an example, the correction increment can be two orders of magnitude less than the amount of detected distortion.

[0057] Figures 5A-5D illustrate one of many scenarios that can be unfolded. In Figure 5A, several gaze vector measurements are taken, which point to locations 124A-124C. The empty circles at locations 124A-124C represent the calculated measured gaze angles. The dark circle at location 126 indicates that this is where the system expected there to be a virtual object. The measured gaze vector locations 124A-124C are used by the system to calculate a statistically relevant location 130 of where the virtual object is likely to be currently located. The measured gaze vectors at locations 124A-124C indicate that the virtual object may have moved from the initial expected location 126 to a modified location 130 that is statistically determined in the direction represented by vector 128. In Figure 5B, the virtual object rendering position is moved in the direction represented by vector 132, which is opposite to the direction represented by vector 128 and smaller in magnitude. The virtual object is assumed to be located at location 130 and has moved in the direction of vector 132 towards the expected rendering location 126 to a new location 134.

[0058] In FIG. 5C, additional data points 124D - 124G are collected, and these are statistically determined to be located at the location 136 where the virtual object was modified. Location 136 is on the side of location 126 opposite to location 130. The change in the object location can be the result of the continued deformation of the display system. Also, when it is determined that the virtual object was at location 130 and / or the virtual object moved in the opposite direction, it is possible that an error occurred due to the noisy data in FIG. 5A. When adjusting the rendering location by vector 132 as shown in FIG. 5B, if the virtual object was actually perceived to be at location 136 as shown in FIG. 5C, it can be seen that through the inaccurate recalibration of FIG. 5B, the virtual object may have been moved to a new location 138. The location of vector 132 in FIG. 5B thus represents how the system "thought" it was moving the virtual object at that point in FIG. 5B, but since vector 132 is in a different location in FIG. 5C where more data is available for the purpose of analyzing the location of the virtual object, it can be seen here that it represents a higher likelihood that the virtual object was moved at the time of FIG. 5B. Vector 132 has the same magnitude and direction in FIGS. 5B and 5C. The only difference in vector 132 between FIGS. 5B and 5C is that the location of vector 132 is different. The location of vector 132 in FIG. 5B represents how the system thought it was moving the virtual object, and the location of vector 132 in FIG. 5C represents what likely occurred when the virtual object was moved in FIG. 5C. In FIG. 5C, the movement of the virtual object from location 136, in the direction represented by vector 132, to location 138, which can be traced back to FIG. 5B, can be seen to be an error because the virtual object moved further away from the expected location 126 instead of moving closer to it. In such an embodiment, it is advantageous that incremental adjustments are made instead of full adjustments.

[0059] In FIG. 5D, additional data points 124H-124L are collected, which indicate that the virtual object is likely to be in the new location 140. Vector 132 is in the same location in FIG. 5D as in FIG. 5C and represents the error that occurred at the time of FIG. 5B. Location 140 passes through location 138, and thus the error caused by moving the virtual object from location 138 in the direction represented by vector 132 is eliminated.

[0060] FIGS. 5A-5D do not illustrate every possible scenario that can unfold, but rather serve to illustrate that by moving the virtual object in small increments, as opposed to a single large movement that attempts to correct all movements of the virtual object due to deformation of the display assembly 24, inaccurate adjustments that may be made based on noisy data are prevented from being noticeable to the user.

[0061] FIG. 6A illustrates a view as seen by a user, including a real-world table 72 and a rendered object in the form of a coffee mug, which can be an extended object 68 in the planes of the shapes 70 and 92 of FIG. 2B, for example. The coffee mug is being moved within the user's view as represented by vector 150. The designation "display" in vector 150 indicates that the movement of the virtual object as shown by vector 150, i.e., the non-deformed shape, is due to the deformation of the display assembly 24 of FIG. 1.

[0062] Figure 6B illustrates the movement of the fixation angle as calculated by the fixation angle calculation module 46 of FIG. 1 based on the view of the eye tracking camera 44 of FIG. 1. A deformation of the display assembly 24 of FIG. 1 results in a movement of the fixation angle as measured by the eye tracking camera 44 in the direction indicated by vector 152. Vectors 150 and 152 of FIGS. 6A and 6B are equal to each other. The movement of the fixation angle calculated in FIG. 6B is thus identical to the movement of the virtual object within the user's field of view as shown in FIG. 6A, according to the tolerance of the eye and tracking algorithms as described with reference to FIG. 4.

[0063] In FIG. 6C, the virtual object is incrementally moved in the direction indicated by vector 154. Vector 154 is in a direction opposite to vector 152, but each vector is only a part of the length of vector 152. The sum of vectors 154 is equal to vector 152, except that they are in opposite directions. If the virtual object is moved by the entire distance of all vectors 154, the virtual object is returned over time to its position prior to the deformation of the display assembly 24 as shown in FIG. 6A, taking into account the previous movement of the virtual object due to the display deformation.

[0064] FIGS. 6A-6C illustrate a scenario where there is no deformation of the eye tracking camera 44 of FIG. 1. Since there is no deformation of the eye tracking camera 44, the measurements made by the eye tracking camera 44 result in a measurement of the fixation angle that matches the actual fixation angle of the user's eye 22 with respect to the display, according to the tolerance discussed above.

[0065] Figures 7A - 7E collectively illustrate the effects that a deformation of the eye - tracking camera 44 of FIG. 1 can have in combination with a deformation of the display. FIG. 7A illustrates the movement of virtual objects within the user's view due to the deformation of the display assembly 24 of FIG. 1 when the deformation of the camera is not considered. FIG. 7A is thus identical to FIG. 6A. Note that any deformation of the eye - tracking camera 44 does not affect the positioning of virtual objects within the user's field of view as illustrated in FIG. 7A, but does affect the gaze vector calculated with respect to the display. Thus, even when the camera deformation also exists and its effects are considered, FIG. 7A will still represent the movement of virtual objects within the user's field of view.

[0066] FIG. 7B illustrates the movement of the gaze angle as calculated by the gaze - angle calculation module 46 of FIG. 1 based on the image data received from the eye - tracking camera 44, without considering the effect of the camera deformation, as in FIG. 7A. FIG. 7B is thus identical to FIG. 6B, assuming no deformation of the eye - tracking camera 44.

[0067] FIG. 7C illustrates the effect of the calculated gaze angle when considering the effect of the deformation of the eye - tracking camera 44 but without the effect of the deformation of the display. Referring to FIG. 2A, the deformation of the eye - tracking camera 44 causes an error in the position measurement of the eye 22 within the view of the eye - tracking camera 44. Such an error in the eye - tracking camera 44 causes a change in the image data that the eye - tracking camera 44 provides to the gaze - angle calculation module 46 of FIG. 1. The gaze angle calculated by the gaze - angle calculation module 46 is thus affected by the deformation of the eye - tracking camera 44. FIG. 7C illustrates the movement of the gaze angle, calculated due to the deformation of the eye - tracking camera 44 and represented by vector 156. The error in gaze - angle accuracy with respect to the display caused by the camera deformation is usually relatively small. The movement of the gaze angle due to the camera deformation is typically about 1 / 20 of the movement of the gaze angle due to the display deformation.

[0068] FIG. 7D illustrates the combination 158 of vectors 152 and 156. In this embodiment, the vector 156 representing the effect of camera deformation is at an angle of less than 90° with respect to the vector 152 representing display deformation. The vector of the combination 158 is thus longer than the vector 152 representing the effect of display deformation.

[0069] In FIG. 7E, the virtual object is moved within the user's field of view as represented by the vector 160. Each vector 160 is in a direction opposite to the combination 58 of FIG. 7D. The virtual object is moved in increments each time the user interacts with a qualified virtual object. Over a period of several days or weeks, the correction vector 160 sums any tolerances required by the tracking algorithm in addition to the combination 158 within the tolerance of the anatomical eye. As described above, the effect of camera deformation is relatively small. The virtual object is thus moved from a location closer to the location shown in FIG. 7A than the location shown in FIG. 7E. In the case of a virtual coffee mug intended to appear to the user as being located on the table 72, the coffee mug will thus return onto or very close to the table.

[0070] FIGS. 8A and 8B are similar to FIGS. 7A and 7B. In FIG. 8C, the effect of camera deformation results in a movement of the viewing angle as represented by the vector 164. The angle between the vector 164 and the vector 152 is greater than 90°.

[0071] FIG. 8D illustrates the combined vector 166. The combined vector 166 represents the calculated change in the viewing angle due to display deformation and camera deformation. The combined vector 166 is smaller than the vector 152 representing the effect of display deformation. The effects of display deformation and camera deformation can be considered to be in "opposite" directions in FIG. 8D and in the "same" direction in FIG. 7D.

[0072] FIG. 9 illustrates one possible solution when the effects of display deformation and camera deformation are in opposite directions with respect to the calculated gaze angle. The correction system 30 of FIG. 1 does not correct the positioning of the virtual object. The user need not concern himself, for example, with whether the "play" button is located on the table or floating at a certain distance above the table. In addition, the play button should function properly as an interface element for the background application.

[0073] Figures 10A - 10C illustrate a solution as an alternative to the solution of FIG. 9. In FIG. 10A, the gaze angle change due to the deformation of the camera is calculated such that the viewing device starts when it is still new, also referred to as the "out of box" state. The calculated change in the eye position with respect to the eye - tracking camera due to camera deformation is determined periodically using the eye - tracking camera 44 and the data analysis of the generated eye - tracking images. The methodology for calculating the eye position or eye center at any given point in time is similar to the methodology described with reference to FIG. 2A. The image of the eye 22 continues to serve as a basis for calculating the eye - center position of each eye with respect to one or more eye - tracking cameras. The change in the eye - center position within the collected image frames can be attributed to the change in the location of the eye - tracking camera with respect to the eye. There is a certain degree of error associated with device conformity and the consistency of how the user wears the device, but the use of multiple image frames in data analysis improves the accuracy of determining eye - tracking camera deformation. For example, the eye center calculated from the eye - tracking images taken during the setup phase of the device is determined to be at a certain coordinate location (x, y, z). Over time, eye - tracking camera deformation can occur such that the camera tilts slightly downward. The position of the eye in the image captured using the deformed eye - tracking camera will change such that the eye center is shown to be at a higher y - axis location within the eye - tracking image, for example, at the coordinate location (x, y + 1, z). The change between the two coordinate locations is linked to the change in the eye - tracking camera, and the difference can be used to correct the rendering location of the virtual content on the display. The eye - tracking camera deformation is represented in FIG. 10A as vector 170 and can occur in one, two, or three dimensions.

[0074] The eye-tracking camera 44 is run continuously, for example, at a rate of 30 frames per second. When determining the deformation of the eye-tracking camera 44, it is not necessary to wait for a specific virtual content rendering and the user to interact for data collection to be performed. A stream of image data may be available for comparison with a baseline at any given point in time. The use of a set of data points from the eye-tracking camera 44 for comparison with the baseline data provides a robust system. For example, the use of at least the last 10 images from the eye-tracking camera 44 can improve accuracy over the use of only one or two images.

[0075] FIG. 10B illustrates that vector 166 is the sum of vectors 152 and 170. Vector 152 can be calculated by subtracting camera deformation vector 170 from vector 166. Since vector 152 represents the effect of the display deformation on the location of the virtual object, the virtual object can be moved in the direction opposite to vector 152.

[0076] In FIG. 10C, the virtual object is incrementally moved as represented by vector 172. The sum of vector 172 is equal to vector 152 except that it is in the opposite direction.

[0077] As shown in FIG. 11, the viewing device 20 may further include a reference system 180 for the purpose of performing calculations as shown in FIGS. 10A-10C. The reference system 180 may include many baseline calculations, images, and / or measurements such as interpupillary distance, eye center location, device fit information, eye shape information, visual axis location, etc. The reference system 180 includes an out-of-box reference fixation angle 182 that is calculated when the viewing device 20 is still new. The out-of-box reference fixation angle 182 is stored in memory. The reference system 180 further has an updated fixation angle 184 stored in memory. The updated fixation angle 184 is calculated on a periodic basis and represents the most recently calculated fixation angle. The reference system 180 further includes a change 186 in the fixation angle due to camera distortion. The change 186 is the difference between the updated fixation angle 184 and the out-of-box reference fixation angle 182. The change 186 is represented in FIG. 10A by the sum of the vectors 170. The correction calculation unit 50 functions to calculate the vector 152 in FIG. 10B. Other aspects of the viewing device 20 in FIG. 11 are the same as the viewing device in FIG. 1, and like reference numerals indicate like components. The out-of-box reference fixation angle is described as being a baseline for comparison, but any other eye characteristic, measurement, calculation, or image may be used instead of or in addition to the out-of-box reference fixation angle.

[0078] FIG. 12 illustrates a method as described above in this specification. At 200, a virtual object is displayed at a selected location, and the eye viewing the virtual object has an expected gaze direction. At 202, an expected gaze vector range is determined based on the selected location. At 204, a user interaction event is detected and the user interacts with the virtual object. At 206, light reflected from the eye is captured using an eye-tracking camera. At 208, a modified gaze vector is calculated based on the light captured by the eye-tracking camera. At 210, a comparison is made between the determined modified gaze vector and the expected gaze vector range. Elements 200-210 can be grouped into element 212, i.e., to detect a deformation of the display assembly, where the deformation makes the virtual object visible at a modified location and the eye has a modified gaze direction. It may be possible to perform element 212 without the specific elements enumerated as elements 200-210. Further, although a gaze vector is calculated, it may be possible to determine the gaze direction using a method other than one that requires calculation of the gaze vector.

[0079] At 214, a determination is made as to whether the actual gaze vector is outside the range of the gaze vector. If the determination at 214 is negative, the process returns to 200. If the determination at 214 is positive, a correction amount and a direction amount for the virtual content rendering location are calculated. At 220, the virtual content rendering location is adjusted by the calculated correction amount and direction. Elements 218 and 220 can be grouped into element 222, i.e., for the display of the virtual object at the corrected location, where the eye viewing the virtual object at the corrected location has a corrected gaze direction that is moved closer to the expected gaze direction than the modified gaze direction.

[0080] FIG. 13 shows a diagrammatic representation of a machine in an exemplary form of a computer system 900 within which a set of instructions for causing the machine to carry out any one or more of the methodologies discussed herein may be executed. In alternative embodiments, the machine may operate as a stand-alone device or may be connected (e.g., networked) to other machines. Further, although only a single machine is illustrated, the term "machine" shall also be construed to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to carry out any one or more of the methodologies discussed herein.

[0081] The exemplary computer system 900 includes a processor 902 (e.g., a central processing unit (CPU), a graphics processing unit (GPU), or both), main memory 904 (e.g., dynamic random access memory (DRAM) such as read only memory (ROM), flash memory, synchronous DRAM (SDRAM), or Rambus DRAM (RDRAM)), and static memory 906 (e.g., flash memory, static random access memory (SRAM), etc.) that communicate with each other via a bus 908 and a laser driver chip 12 or other light source driver.

[0082] The computer system 900 may further include a disk drive unit 916 and a network interface device 920.

[0083] The disk drive unit 916 includes a machine-readable medium 922 on which is stored one or more sets of instructions 924 (e.g., software) embodying any one or more of the methodologies or functions described herein. The software may also reside, completely or at least partially, within the main memory 904 and / or within the processor 902 during execution thereof by the computer system 900, and the main memory 904 and the processor 902 also constitute a machine-readable medium.

[0084] Software may also be transmitted or received via network 928 through network interface device 920.

[0085] Machine-readable medium 924 is illustrated in the exemplary embodiments as a single medium, but the term "machine-readable medium" should be interpreted to include a single medium or multiple media (e.g., a centralized or distributed database and / or associated cache and server) that store one or more sets of instructions. The term "machine-readable medium" should also be interpreted to include any medium that is capable of storing, encoding, or carrying a set of instructions for machine execution and that causes a machine to perform any one or more of the methodologies of the present invention. The term "machine-readable medium" shall accordingly be interpreted to include, without limitation, solid-state memory, optical and magnetic media, and carrier wave signals.

[0086] Laser driver chip 12 includes a data store 161 and its own processor 162. Data store 161 is used to store instructions and data structures specific to the operation of the laser source. Processor 162 has access to a data structure for reading instructions from the data store and executing routines to drive the laser source so that the laser source generates laser light. The laser source forms part of a projector that receives data such as video data. A scanning device forms part of the projector, which enables the projector to display laser light over a two-dimensional area and, in some cases, within a three-dimensional space, and any pattern, color, saturation, and other light qualities created by the projector are based on values within the video data.

[0087] Although the laser source and the laser driver chip 12 have been illustrated and discussed, it may be possible to use other display systems. Other display systems may include, for example, displays that utilize light emitting diode (LED) technology, organic light emitting diode (OLED) technology, high brightness light emitting diode (SLED), or the like.

[0088] Although an exemplary embodiment has been described and shown in the accompanying drawings, such embodiments are merely illustrative of the invention and not limitations thereof, and it should be understood that the invention is not limited to the specific structures and arrangements shown and described, as modifications may occur to those skilled in the art.

Claims

【Claim 1】 The invention described in this specification.

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