Joint bend estimation

Abstract

A system for correcting frame curvature of an augmented reality system is provided. A combination of strain gauges and visual inertial odometers is used to determine strain in the frame. An initial model between strain gauge measurements and actual frame spatial relationships is based on finite element analysis or calibration. During an initial visual inertial odometer data calculation phase, the augmented reality system uses strain data from a strain gauge mounted to the frame to calculate bending or strain of the frame. The subsequent visual inertial odometer data computes a corrected framework model for generating the framework. The corrected framework model is used to calculate corrected tracking data and corrected virtual overlays, which are used to generate a virtual overlay for use in an AR experience provided by an augmented reality system.

Description

Technical Field

[0001] This application claims the benefit of U.S. patent application serial number 18 / 172,874, filed on February 22, 2023, the entire contents of which are hereby incorporated by reference. Technical Field

[0002] The present disclosure relates generally to user interfaces, and more particularly to user interfaces used in augmented reality and virtual reality. Background Art

[0003] Head-mounted devices can be implemented with transparent or translucent displays through which the user of the head-mounted device can view the surrounding environment or real-world scenes. Such devices enable users to view the real-world scene through a transparent or translucent display, and also to see objects generated for display (e.g., virtual objects such as renderings of 2D or 3D graphic models, images, videos, text, etc.), which appear as part of the real-world scene and / or are superimposed on the real-world scene. This is commonly referred to as "augmented reality" or "AR". Head-mounted devices can also completely block the user's field of view and display a virtual environment through which the user can move or be moved. This is commonly referred to as "virtual reality" or "VR". In a hybrid form, an imaging device is used to capture a view of the real-world scene, and then the view, along with the augmentations, is displayed to the user on a display that blocks the user's eyes. As used herein, unless the context indicates otherwise, the term AR refers to augmented reality, virtual reality, and any mixture of these technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] To easily identify the discussion of any particular element or act, the highest digit or digits in a reference number refer to the figure number in which the element is first introduced.

[0005] Figure 1 is a perspective view of a head-mounted device according to some examples.

[0006] Figure 2 Shown according to some examples Figure 1 Another view of the headset.

[0007] Figure 3 is a diagram of forces and their effects on a frame of a head-mounted AR device according to some examples.

[0008] Figure 4A Misalignment errors caused by yaw bending of a head-mounted AR system in response to lateral forces acting on a frame of the head-mounted AR system are shown, according to some examples.

[0009] Figure 4B Misalignment errors caused by pitch movement of a head-mounted AR system are shown, according to some examples.

[0010] Figure 5A is a flow chart of a frame curvature correction method used by a head-mounted AR system according to some examples.

[0011] Figure 5B is a collaboration diagram of components of an AR system according to some examples.

[0012] Figure 6 is a diagrammatic representation of a machine according to some examples within which a set of instructions may be executed, for causing the machine to perform any one or more of the methodologies discussed herein.

[0013] Figure 7 is a block diagram illustrating a networked system including details of a head-mounted AR system according to some examples.

[0014] Figure 8 is a block diagram illustrating a software architecture within which the present disclosure may be implemented, according to some examples.

[0015] Figure 9 is a block diagram illustrating an example messaging system for exchanging data (eg, messages and associated content) over a network, according to some examples. DETAILED DESCRIPTION

[0016] When a user of a head-mounted device wears the device, a virtual overlay of an AR experience is provided to the user. By wearing the head-mounted device, various forces act on the head-mounted device, causing strain and bending. Therefore, it is desirable to have a mechanism for generating a virtual overlay that corrects for the bending of the head-mounted device.

[0017] Understanding the spatial relationships of the system components of a head-mounted AR device is useful for generating accurate virtual overlays for AR experiences. Ergonomic and visually appealing frame designs for head-mounted AR devices result in lightweight glasses. However, such designs may have low stiffness, and this may cause the spatial relationships between different components of the head-mounted AR device (e.g., displays, imaging devices such as cameras, inertial measurement units, and projectors) to change over time. Such relationships may also change during normal operation by the user simply putting on the head-mounted AR device, walking, or touching the frame of the head-mounted device. This may result in incorrect sensing of the surrounding world (e.g., stereo depth estimation), which leads to an unrealistic AR experience. The examples disclosed herein provide coupling strain gauges with a visual inertial odometry (VIO) system to measure changing spatial relationships and provide an improved AR experience for a flexible and ergonomic frame design.

[0018] In some examples, the combination of strain gauge sensors and a VIO system includes a physical frame model that defines a frame of a head-mounted AR device that is part of an AR system. Based on finite element analysis or calibration, a correlation between the strain gauge measurements and the actual frame spatial relationship is determined. During use, the AR system uses strain data from strain gauges mounted to the frame to select a seed for calculation of the frame's bending or strain during an initial VIO data calculation phase. Subsequent VIO data calculations are used to generate a corrected frame model of the frame. The corrected frame model is used to calculate corrected tracking data and corrected virtual overlays, which are used to generate virtual overlays used in the AR experience.

[0019] In some examples, inertial motion data is used to seed the VIO data generation process.

[0020] In some examples, strain gauge data is used instead of VIO data to provide a low-power option for generating a corrected frame model.

[0021] In some examples, an AR system includes a frame and one or more strain gauges operable to measure strain of the frame. The AR system also includes one or more imaging devices mounted to the frame. During operation, the AR system measures tracking video frame data of a real-world scene being viewed by a user of the AR system. As the tracking video frame data is being captured, the AR system also measures strain data of the strain of the frame of the AR system. The AR system generates a corrected frame model of the frame based on the strain data, the tracking video frame data, and the frame model of the frame. The AR system generates corrected tracking data using the corrected frame model and the tracking video frame data. The corrected tracking data is used to generate a virtual overlay, and the corrected frame model is used by an optical engine to render the virtual overlay for display.

[0022] Other technical features may be readily apparent to those skilled in the art from the following drawings, descriptions, and claims.

[0023] Figure 1 is a head-mounted AR system according to some examples (e.g., Figure 1 A stereoscopic view of a head-mounted AR device 100).

[0024] As used herein, unless an alternative meaning is indicated, directional terms such as, but not limited to, “up,” “upper,” “down,” “lower,” “vertical,” “horizontal,” “lateral,” “left,” “right,” “forward,” and “backward” are to be interpreted according to the perspective of a user wearing a head-mounted AR system (such as head-mounted AR device 100).

[0025] The head-mounted AR device 100 may include a frame 102 made of any suitable material, such as plastic or metal, including any suitable shape memory alloy. In one or more examples, the frame 102 includes a first or left optical element holder 104 (e.g., a display or lens holder) and a second or right optical element holder 106 connected by a bridge portion 112. A first or left optical element 108 and a second or right optical element 110 may be disposed within the respective left and right optical element holders 104, 106. The right and left optical elements 110, 108 may be lenses, displays, display components, or a combination thereof. Any suitable display component may be disposed in the head-mounted AR device 100.

[0026] Frame 102 additionally includes a left arm or temple piece 122 and a right arm or temple piece 124. In some examples, frame 102 can be formed from a single piece of material so as to have a unitary or unitary construction.

[0027] The head-mounted AR device 100 may include a computing system such as a computer 120, which may be of any suitable type to be carried by the frame 102 and, in one or more examples, may be of a suitable size and shape to be partially disposed in one of the left temple piece 122 or the right temple piece 124. The computer 120 may include multiple processors, memory, and various communication components that share a common power supply. As discussed below, the various components of the computer 120 may include low-power circuitry, high-speed circuitry, and a display processor. Various other examples may include these elements in different configurations or integrated together in different ways. Additional details of various aspects of the computer 120 may be implemented as shown in the data processor 702 discussed below.

[0028] The computer 120 additionally includes a battery 118 or other suitable portable power supply. In some examples, the battery 118 is disposed in the left temple piece 122 and electrically coupled to the computer 120 disposed in the right temple piece 124. In some examples, the battery 118 includes two separate components, each disposed in a respective temple piece. The head-mounted AR device 100 may include a connector or port (not shown) suitable for charging the battery 118, a wireless receiver, transmitter, or transceiver (not shown), or a combination of such devices.

[0029] The head-mounted AR device 100 includes a first or left imaging device 114 and a second or right imaging device 116. In some examples, one or more imaging devices of the head-mounted AR device 100 include an imaging sensor and an optical component, such as, but not limited to, a camera. In some examples, the imaging sensor senses electromagnetic radiation in the visible light spectrum. In some examples, the imaging sensor senses electromagnetic radiation in the infrared spectrum.

[0030] In some examples, the head-mounted AR device 100 also includes one or more light sources, such as light emitting diodes (LEDs). In some examples, one or more LEDs of the AR system operate in the infrared light frequency range. In some examples, the one or more light sources emit diffuse light. In some examples, the one or more light sources project light in a specified pattern.

[0031] In some examples, one or more imaging devices of the head-mounted AR device 100 include one or more laser imaging, detection, and ranging (LIDAR) devices.

[0032] Although two imaging devices are depicted, other examples contemplate the use of a single or additional (i.e., more than two) imaging devices. In one or more examples, the head-mounted AR device 100 includes any number of input sensors or other input / output devices in addition to the left imaging device 114 and the right imaging device 116. Such sensors or input / output devices may additionally include biometric sensors, position sensors, motion sensors, and the like.

[0033] In some examples, the left imaging device 114 and the right imaging device 116 provide video frame data for use by the head-mounted AR device 100 to extract 3D information from the real-world scene.

[0034] One or more strain gauges 126 are attached to the frame 102 at the bridge portion 112 of the frame 102. The one or more strain gauges 126 are operable to measure horizontal or longitudinal strain of the frame 102. In some examples, the one or more strain gauges 126 are configured to measure vertical or latitudinal strain of the frame 102. In some examples, the one or more strain gauges 126 are configured to measure torsional strain of the frame 102. In some examples, one or more of the strain gauges 126 are located on other portions of the frame 102, such as, but not limited to, a portion of the right optics holder 106 or a portion of the left optics holder 104.

[0035] The head-mounted AR device 100 may also include a touchpad mounted to or integrated with one or both of the left and right temple pieces 122, 124. In some examples, the touchpad is generally arranged vertically, approximately parallel to the user's temples. As used herein, generally vertically aligned means that the touchpad is more vertical than horizontal, but potentially more vertical than that. Additional user input may be provided by one or more buttons, which, in the example shown, are located on the outer upper edges of the left and right optical element holders 104, 106. The one or more touchpads and buttons provide a means by which the head-mounted AR device 100 can receive input from the user of the head-mounted AR device 100.

[0036] Figure 2 The head-mounted AR device 100 is shown from the perspective of a user wearing the head-mounted AR device 100. For clarity, the Figure 1 As shown in the Figure 1 As described in Figure 2 The head-mounted AR device 100 shown in FIG. 1 includes a left optical element 108 and a right optical element 110 fixed in a left optical element holder 104 and a right optical element holder 106 , respectively.

[0037] The head-mounted AR device 100 includes a front optical assembly 202 including a right projector 204 and a right near-eye display 206 , and a front optical assembly 210 including a left projector 212 and a left near-eye display 216 .

[0038] In some examples, the right near-eye display 206 and the left near-eye display 216 are waveguides. The waveguides include reflective or diffractive structures (e.g., gratings and / or optical elements such as mirrors, lenses, or prisms). Light 208 emitted by the right projector 204 encounters the diffractive structure of the waveguide of the right near-eye display 206, which directs the light toward the user's right eye to provide an image on or in the right optical element 110, which is superimposed on the user's view of the real-world scene. Similarly, light 214 emitted by the left projector 212 encounters the diffractive structure of the waveguide of the left near-eye display 216, which directs the light toward the user's left eye to provide an image on or in the left optical element 108, which is superimposed on the user's view of the real-world scene. The combination of the GPU, the forward optical assembly 202, the left optical element 108, and the right optical element 110 provides the optical engine of the head-mounted AR device 100. The head-mounted AR device 100 uses the optical engine to generate an overlay of the user's real-world scene view to the user of the head-mounted AR device 100, where the overlay includes a display user interface.

[0039] However, it will be understood that other display technologies or configurations may be utilized within the optical engine to display images to the user within the user's field of view. For example, an LCD, LED, or other display panel or surface may be provided instead of the right projector 204 and waveguide.

[0040] In use, information, content, and various user interfaces are presented to the user of the head-mounted AR device 100 on the near-eye display. As described in more detail herein, the user can then use the touchpad and / or buttons, on an associated device (e.g., Figure 7 The user can interact with the head-mounted AR device 100 through voice input or touch input on the client device 726 shown in FIG, and / or hand movements, positions, and postures detected by the head-mounted AR device 100.

[0041] Figure 3FIG2 is a diagram illustrating forces and their effects on a frame of a head-mounted AR device according to some examples. The head-mounted AR device 100 includes a frame 102. A forward-facing left imaging device 114 is attached to the frame at a left distal portion and has a left optical axis 304 projected forward from the left imaging device 114. A forward-facing right imaging device 116 is attached to the frame at a right distal portion and has a right optical axis 302 projected forward from the right imaging device 116. The frame 102 is attached to a left temple piece 122 and a right temple piece 124.

[0042] One or more strain gauges 126 are attached to the frame 102 at the bridge portion 112 of the frame 102. The one or more strain gauges 126 are operable to measure horizontal or longitudinal strain of the frame 102. In some examples, the one or more strain gauges 126 are configured to measure vertical or latitudinal strain of the frame 102. In some examples, the one or more strain gauges 126 are configured to measure torsional strain of the frame 102. In some examples, the one or more strain gauges 126 are located on other portions of the frame 102.

[0043] Frame 102 includes an inertial measurement unit (IMU) 128 that is configured to measure the physical orientation or attitude of frame 102. In some examples, IMU 128 is operable to measure the rotation angles of frame 102 about pitch rotation axis 322, roll rotation axis 318, and yaw rotation axis 324. In some examples, IMU 128 is operable to measure rotational movement of frame 102 about pitch rotation axis 322, roll rotation axis 318, and yaw rotation axis 324, as well as translational movement of frame 102 in 3D space.

[0044] When a horizontal force 308 acts on the right temple piece 124 and the left temple piece 122, the frame 102 may experience opposing yaw bending motions, such as right yaw bending motion 310 and left yaw bending motion 312, at distal portions of the frame 102 where the left temple piece 122 and the right temple piece 124 are attached to the frame 102. These opposing yaw bending motions may induce yaw bending strain in the frame 102 about the yaw rotation axis 324. The one or more strain gauges 126 are operable to measure the yaw bending strain in the frame 102. The yaw bending strain is used to determine a relative change between a right optical axis yaw angle 316 of the right imaging device 116 and a left optical axis yaw angle 328 of the left imaging device 114.

[0045] When an unbalanced vertical force acts on the frame 102, the frame 102 may experience opposing yaw bending motions, such as right yaw bending motion 310 and left yaw bending motion 312, at distal portions of the frame 102 where the left and right temple pieces 122, 124 are attached to the frame 102. These opposing yaw bending motions may induce yaw bending strain in the frame 102 about the yaw rotation axis 324. The one or more strain gauges 126 are operable to measure the yaw bending strain in the frame 102. The yaw bending strain is used to determine a relative change between a right optical axis yaw angle 316 of the right imaging device 116 and a left optical axis yaw angle 328 of the left imaging device 114.

[0046] In some examples, torsional strains in frame 102 may be caused by unbalanced rotational forces acting on portions of frame 102. These torsional strains may induce roll bending strains in frame 102 about roll rotation axis 318. One or more strain gauges 126 can be operable to measure the roll bending strains in frame 102. The roll bending strains are used to determine the relative change between the right optical axis roll angle of right imaging device 116 and the left optical axis roll angle of left imaging device 114.

[0047] In some examples, torsional strain in frame 102 may induce pitch bending strain in frame 102 about pitch rotation axis 322. One or more strain gauges 126 can be operable to measure the pitch bending strain in frame 102. The pitch bending strain is used to determine the relative change between the right optical axis pitch angle of right imaging device 116 and the left optical axis pitch angle of left imaging device 114.

[0048] In some examples, there are two or more IMUs, and each IMU is associated with an imaging device.The roll and / or pitch bending of the frame 102 can be estimated based on the difference in roll movement and pitch movement determined by the two or more IMUs.

[0049] Figure 4A and Figure 4B1 shows depth misalignment errors caused by yaw bending and pitch movement of a head-mounted AR system (e.g., glasses 404) in response to lateral and vertical forces acting on the frame of the head-mounted AR system, according to some examples. When worn by a user, the head-mounted AR system (e.g., glasses 404) experiences optical misalignment errors caused by deformation or bending of the frame 406 of the head-mounted AR system. When the user places the head-mounted AR system on their head, the temple pieces (e.g., left temple piece 430 and right temple piece 432) strain due to opposing lateral forces 412 and lateral forces 414, causing the frame 406 to bend along its length, which is referred to herein as "yaw bending," as indicated by bend lines 416a, 416b, 416c, and 416d. In addition, when the glasses 404 are subjected to vertical forces on one or both of the temple pieces of the glasses 404, the glasses 404 experience pitch movement. The yaw bending and pitch movement can cause misalignment errors in the optical components of the AR glasses 404. These misalignment errors can result in tracking errors when tracking data is generated by the AR system, and in misalignment between the virtual overlays provided by the AR system to the user and the physical objects and features of the real-world scene being viewed by the user while wearing the head-mounted AR system.

[0050] The yaw bend may cause the left imaging device 420 and the right imaging device 424 to experience yaw motion. The yaw motion may cause the left optical axis 418 of the left imaging device 420 to become misaligned, as indicated by misaligned left optical axis 426. The yaw motion may also cause the right optical axis 422 of the right imaging device 424 to become misaligned, as indicated by misaligned right optical axis 428. When using the video frame data of the imaging devices to stereoscopically determine the position of a physical feature 402 in a real-world scene, the system causes a depth or Z error 410 in the Z axis because the physical feature 402 is determined to be at a different location when the AR system generates tracking data for the feature in the real-world scene and, therefore, appears to be a distinct physical feature 408.

[0051] In a similar manner, when virtual objects of a virtual overlay of an AR experience are rendered in video frame data and provided to a user of a head-mounted AR system, the user will experience a misalignment of the provided virtual objects with the real-world scene, as indicated by left viewing optical axis misalignment 446 of left viewing optical axis 444 and right viewing optical axis misalignment 450 of right viewing optical axis 448.

[0052] In the correctly aligned video frame 434 of the virtual overlay, the AR system correctly displays the virtual object 436 aligned with the real-world scene feature 438. The misaligned video frame 442 causes the AR system to display the virtual object 440 in an incorrect position (with respect to the real-world scene feature 438).

[0053] Figure 5A is a flow chart of a frame curvature correction method 500 used by a head-mounted AR system (e.g., head-mounted AR device 100) to correct curvature of a frame (e.g., frame 102) of the head-mounted AR system, and Figure 5B is a collaboration diagram of components of an AR system according to some examples.

[0054] In operation 502, the AR system uses one or more imaging devices 522 (eg, Figure 1 The left imaging device 114 and the right imaging device 116 of the head-mounted AR device 100 are used to capture tracking video frame data 528 of the real-world scene being viewed by the user of the head-mounted AR device 100.

[0055] The AR system also measures strain data 540 using one or more strain gauges 126 mounted on the bridge portion 112 of the frame 102. The strain data 540 includes measurements of the yaw strain, or amount of yaw bending, of the frame 102 as the tracking video frame data 528 is captured by the one or more imaging devices 522. In some examples, one or more of the strain gauges 126 are mounted on portions of the frame 102 other than the bridge portion 112 of the frame 102 and are operable to measure strain of the frame 102 other than the strain on the bridge portion 112 of the frame 102.

[0056] In some examples, one or more strain gauges 126 can be operable to measure the amount of pitch strain or pitch bending of frame 102. In additional examples, one or more strain gauges 126 can be operable to measure the amount of roll strain or roll bending of frame 102.

[0057] In operation 504, the AR system generates visual-inertial odometry data 546 based on the tracking video frame data 528, the strain data 540, and the frame model 516 using the visual-inertial odometry component 544. The frame model 516 includes data of a geometric model of the frame 102, such as, but not limited to, data of geometric relationships between one or more imaging devices 522, such as the left imaging device 114 and the right imaging device 116 of the head-mounted AR device 100, which defines the spatial positions and geometric relationships between various components of the frame 102. The frame model 516 also includes data of the positions and geometric relationships between components of the optical engine 524, such as the left projector 212 and the left optical element 108 of the head-mounted AR device 100, and data of the positions and geometric relationships between the right projector 204 and the right optical element 110 of the head-mounted AR device 100. The frame model 516 also includes frame flexural rigidity values ​​or stiffness values ​​of the frame 102 at various locations along the frame, such as data on the flexural rigidity of the frame when yaw bending forces, pitch movement forces, and roll movement forces act on the frame 102 via the left temple piece 122 and the right temple piece 124 of the head-mounted AR device 100.

[0058] In some examples, the data for frame model 516 (including the frame flexural stiffness value and the frame model) is generated based on a finite element analysis of the frame as designed. In some examples, the data for frame model 516 (including the frame flexural stiffness value and the frame model) is determined through testing and calibration of the frame as constructed. In some examples, the data for frame model 516 (including the frame flexural stiffness value and the frame model) is generated based on a combination of a finite element analysis of the frame as designed and testing and calibration of the frame as constructed.

[0059] In some examples, visual-inertial odometry component 544 determines yaw bend data for frame 102 based on strain data 540 and a lookup table that relates strain data 540 to an amount of yaw bend for frame 102. The AR system uses the yaw bend data during the capture of tracking video frame data 528 to determine a calibrated frame model that indicates the spatial relationship of one or more imaging devices 522. Visual-inertial odometry component 544 generates visual-inertial odometry data 546 based on the tracking video frame data 528 and the calibrated frame model by extracting features from consecutive video frames of the tracking video frame data 528. The AR system identifies the extracted one or more features as reference features to be tracked between consecutive video frames. The AR system determines the apparent 3D position of the reference feature in the consecutive video frames based on the video frame data of the reference feature and the spatial relationship and physical position of the one or more imaging devices 522 determined by the calibrated frame model. By comparing the apparent 3D positions of reference features in consecutive video frames, the AR system can determine the physical orientation or pose and physical movement or translation of frame 102 based on changes in the apparent 3D positions of reference features between consecutive video frames of tracking video frame data 528.

[0060] In some examples, the visual inertial odometry component 544 extracts reference features from the tracking video frame data 528 using computer vision methods including, but not limited to, Harris corner detection, Shi-Tomasi corner detection, scale-invariant feature transform (SIFT), speeded-up robust features (SURF), features from accelerated segment tests (FAST), oriented FAST, and rotated BRIEF (ORB), among others.

[0061] In some examples, the AR system uses an inertial measurement unit 128 (IMU) mounted to the frame 102 of the head-mounted AR device 100 to determine inertial motion data 530 for the frame 102. The inertial motion data 530 includes data about the physical orientation or pose of the frame 102 as the one or more imaging devices 522 capture tracking video frame data 528, such as, but not limited to, the yaw angle of the frame 102, the pitch angle of the frame 102, and the roll angle of the frame 102. In some examples, the inertial motion data 530 includes translation data, such as the yaw movement of the frame 102, the pitch movement of the frame 102, the roll movement of the frame 102, and the spatial translation of the frame 102 as the one or more imaging devices 522 capture tracking video frame data 528. The AR system generates visual-inertial odometry data 546 based on the inertial motion data 530, the tracking video frame data 528, and the strain data 540. For example, the AR system determines seed or initial inertial odometry data based on the inertial motion data 530. The AR system uses the initial inertial odometry data during subsequent generation of visual inertial odometry data 546 based on the tracking video frame data 528 , the strain data 540 , the frame model 516 , and the initial inertial odometry data.

[0062] In some examples, visual inertial odometry component 544 generates visual inertial odometry data 546 based on classifying tracking video frame data 528, inertial motion data 530, and strain data 540 using artificial intelligence methods and a visual inertial odometry model previously generated using machine learning methods. In some examples, the visual inertial odometry model includes, but is not limited to, a neural network, a learning vector quantization network, a logistic regression model, a support vector machine, a random decision forest, a naive Bayes model, a linear discriminant analysis model, a K-nearest neighbor model, and the like. In some examples, the machine learning method may include, but is not limited to, supervised learning, unsupervised learning, semi-supervised learning, reinforcement learning, dimensionality reduction, self-learning, feature learning, sparse dictionary learning, anomaly detection, and the like.

[0063] In some examples, visual inertial odometry component 544 uses a Kalman filter approach to classify tracking video frame data 528 , inertial motion data 530 , and strain data 540 to determine visual inertial odometry data 546 .

[0064] In operation 506, the AR system generates corrected frame model data 534 based on the visual-inertial odometry data 546 and the frame model 516 using the frame model correction component 520. For example, the frame model correction component 520 uses the physical orientation or pose data and translation data of the frame 102 included in the visual-inertial odometry data 546 to determine the forces acting on the frame 102. As the AR system captures tracking video frame data 528 using one or more imaging devices 522, the frame model correction component 520 uses the forces acting on the frame 102 and the frame flexural stiffness values ​​included in the frame model 516 to calculate the strain of the frame 102. The frame model correction component 520 uses the geometric data of the frame 102 included in the frame model 516 and the strain of the frame to calculate changes in the spatial relationship between the one or more imaging devices 522 and the optical components of the optical engine 524. In some examples, the corrected frame model data 534 includes data on the corrected geometric relationship between one or more imaging devices 522 (e.g., the left imaging device 114 and the right imaging device 116 of the head-mounted AR device 100) as the frame 102 is subjected to the measured force or pressure. The corrected frame model data 534 also includes data on the corrected geometric relationship between the left projector 212 and the left optical element 108, and data on the corrected geometric relationship between the right projector 204 and the right optical element 110 of the head-mounted AR device 100.

[0065] In some examples, the frame model correction component 520 uses strain data 540 received from one or more strain gauges 126 to generate corrected frame model data 534. For example, the frame model correction component 520 generates yaw bending data for the frame 102 based on the strain data 540. The frame model correction component 520 uses the yaw bending data and the frame model 516 to generate the corrected frame model data 534. In some examples, the amount of yaw bending is determined based on a lookup table and the strain data 540.

[0066] In operation 508, the AR system uses a tracking data correction component 542 to generate corrected tracking data 536 based on the corrected frame model data 534 and the tracking video frame data 528. The tracking data correction component 542 identifies features of the physical object in the tracking video frame data 528 and maps these features into a 3D model of the real-world scene according to a 3D coordinate system (e.g., a 3D Cartesian coordinate system or a 3D polar coordinate system). For example, when two imaging devices are used to capture the tracking video frame data 528, the distance between the imaging devices and the angle of the optical axes of the two imaging devices can be used along with the video frame data of the feature of the physical object to determine the 3D coordinates of the position of the object using triangulation. As another example, when a single imaging device is used to capture the tracking video frame data 528, the angle of the optical axis of the imaging device and the assumed physical size of the feature can be used to determine the 3D coordinates of the position of the feature. The corrected frame model data 534 includes the corrected distance between the imaging devices mounted on the frame and the corrected optical axis angle of the imaging devices. The use of the corrected distance and optical axis angle of the imaging device reduces errors in the 3D coordinates determined by the tracking data correction component 542 of the locations of features identified in the tracking video frame data 528 .

[0067] In operation 510, the AR system uses AR application 518 to generate virtual overlay data 538 using corrected tracking data 536. Virtual overlay data 538 includes data for virtual objects generated by AR application 518, which are used to create a virtual overlay that is presented to a user of the AR system using optical engine 524. Corrected tracking data 536 is used to map virtual objects into a 3D model of a real-world scene, such that when the virtual objects are rendered into video frame data and presented to the user in a display by optical engine 524, the virtual objects appear to be located in the real-world scene in a specific relationship to features of physical objects identified in corrected tracking data 536. For example, the virtual overlay may include a user interface composed of virtual objects that a user interacts with using the user's hands. The virtual objects appear in the virtual overlay in apparent locations near the position of the user's hands, as determined from corrected tracking data 536, allowing the user to reach and interact with the virtual objects.

[0068] In operation 512, the AR system uses the virtual overlay rendering component 526 to generate corrected virtual overlay video frame data 532 by rendering the virtual objects of the virtual overlay into the video frame data using the virtual overlay data 538 and the corrected frame model data 534. The corrected virtual overlay video frame data 532 is provided to the user in a display via the optical engine 524. The optical engine 524 includes a projector, such as the left projector 212 and the right projector 204 of the head-mounted AR device 100, to project images of the corrected virtual overlay video frame data 532 onto optical elements, such as the left optical element 108 and the right optical element 110 of the head-mounted AR device 100. Misalignment may occur when force or pressure acts on the temple pieces and the frame of the head-mounted AR device 100. The virtual overlay rendering component 526 uses the corrected frame model data 534 to correct the video frame data generated by rendering the virtual object of the virtual overlay data 538 to account for misalignment between the projector and the optical elements of the head-mounted AR device 100.

[0069] In operation 514, the AR system uses the optical engine 524 to provide a virtual overlay to the user based on the corrected virtual overlay video frame data 532. For example, one or more projectors of the head-mounted AR device 100 project an image included in the corrected virtual overlay video frame data 532 onto one or more optical elements of the head-mounted AR device 100, and the user can see the virtual overlay superimposed on the real-world scene viewable by the user through the optical elements.

[0070] In some examples, the AR system recalibrates the strain gauges 126 based on the strain data 540. For example, a user places the frame 102 of the head-mounted AR device 100 in a designated relaxed configuration, in which measurements of the output of the strain gauges 126 can be determined on the relaxed or unstressed frame 102. In some examples, the frame 102 can be placed on a flat, horizontal surface, such as a tabletop, with its corresponding temple pieces fully open and unstressed. In this configuration, the strain gauges 126 are relaxed, and the strain gauges 126 are zeroed or recalibrated using the strain data 540. This enables the AR system to recalibrate the strain gauges 126 as they age.

[0071] In some examples, the configuration of the head-mounted AR device 100 is confirmed based on tracking video frame data 528. For example, tracking video frame data 528 can be used to determine that the head-mounted AR device 100 is not being worn by the user by detecting that the field of view of the imaging device 522 includes a flat surface extending from the base of the frame. In some examples, the configuration of the head-mounted AR device 100 is confirmed based on inertial movement data 530. For example, a movement value of the inertial movement data 530 can be compared to a threshold movement value. In response to determining that the movement value does not exceed the threshold movement value, the AR system determines that the head-mounted AR device 100 is not being worn by the user.

[0072] In some examples, the user places the head-mounted AR device 100 in a designated stressed configuration that applies a known amount of stress to the frame 102. For example, the user can balance the frame 102 on the user's finger at the bridge portion 112 of the frame 102, thereby applying stress to the bridge portion 112. In some examples, the user can hold the head-mounted AR device 100 by one or more of the temple pieces. The strain data 540 collected while the head-mounted AR device 100 remains in the stressed configuration is then used to recalculate sensitivity or recalibrate the strain gauges 126.

[0073] In some examples, as the head-mounted AR device 100 captures tracking video frame data 528 of an alignment object, one or more strain gauges 126 are calibrated based on the tracking video frame data, inertial motion data, and strain data captured from the head-mounted AR device 100 in both an unstressed and stressed configuration. For example, the head-mounted AR device 100 captures initial tracking video frame data, initial inertial motion data, and initial strain data when the frame 102 of the head-mounted AR device 100 is in a relaxed position at a specified pose and pointing toward a specified alignment object, such that the initial tracking video frame data captures the alignment object. Without repositioning the head-mounted AR device 100, the user places the frame 102 in a specified stressed configuration that applies a known amount of stress to the frame 102. The head-mounted AR device 100 captures stressed tracking video frame data, stressed inertial motion data, and stressed strain data, such that the stressed tracking video frame data captures the alignment object. The head-mounted AR device 100 recalibrates the sensitivity of the one or more strain gauges 126 based on the initial tracking video frame data, the initial inertial movement data, the initial strain data, the stressed tracking video frame data, the stressed inertial movement data, and the stressed strain data.

[0074] Figure 6is a diagrammatic representation of a machine 600 within which instructions 610 (e.g., software, programs, applications, applet, apps, or other executable code) may be executed for causing the machine 600 to perform any one or more of the methodologies discussed herein. The machine 600 may be used as Figure 1 The computer 120 of the AR system of the head-mounted AR device 100. For example, the instructions 610 can cause the machine 600 to perform any one or more of the methods described herein. The instructions 610 convert the general unprogrammed machine 600 into a specific machine 600 that is programmed to perform the functions described and illustrated in the manner described. The machine 600 can operate as a standalone device or can be coupled (e.g., networked) to other machines. In a networked deployment, the machine 600 can operate in the capacity of a server machine or a client machine in a server-client network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. The machine 600, in combination with other components of the AR system, may function as, but is not limited to, a server, a client, a computer, a personal computer (PC), a tablet computer, a laptop computer, a netbook, a set-top box (STB), a PDA, an entertainment media system, a cellular phone, a smartphone, a mobile device, a head-mounted device (e.g., a smartwatch), a smart home device (e.g., a smart appliance), other smart devices, a web appliance, a network router, a network switch, a network bridge, or any machine capable of sequentially or otherwise executing instructions 610 specifying actions to be taken by the machine 600. Furthermore, while a single machine 600 is shown, the term "machine" may also be understood to include a collection of machines that individually or collectively execute instructions 610 to perform any one or more of the methodologies discussed herein.

[0075] The machine 600 may include a processor 602, a memory 604, and an I / O device interface 606 that may be configured to communicate with each other via a bus 644. In an example, the processor 602 (e.g., a central processing unit (CPU), a reduced instruction set computing (RISC) processor, a complex instruction set computing (CISC) processor, a graphics processing unit (GPU), a digital signal processor (DSP), an ASIC, a radio frequency integrated circuit (RFIC), another processor, or any suitable combination thereof) may include, for example, a processor 608 that executes instructions 610 and a processor 612. The term "processor" is intended to include multi-core processors, which may include two or more independent processors (sometimes referred to as "cores") that may execute instructions concurrently. Although Figure 6Multiple processors 602 are shown, but the machine 600 may include a single processor with a single core, a single processor with multiple cores (e.g., a multi-core processor), multiple processors with a single core, multiple processors with multiple cores, or any combination thereof.

[0076] The memory 604 includes a main memory 614, a static memory 616, and a storage unit 618, all of which are accessible by the processor 602 via the bus 644. The main memory 604, the static memory 616, and the storage unit 618 store instructions 610 that embody any one or more of the methodologies or functions described herein. The instructions 610 may also reside, completely or partially, within the main memory 614, within the static memory 616, within a non-transitory machine-readable medium 620 within the storage unit 618, within one or more of the processors 602 (e.g., within a cache memory of a processor), or any suitable combination thereof during execution thereof by the machine 600.

[0077] The I / O device interface 606 couples the machine 600 to the I / O devices 646. One or more of the I / O devices 646 may be components of the machine 600, or may be separate devices. The I / O device interface 606 may include various interfaces to the I / O devices 646 that are used by the machine 600 to receive input, provide output, generate output, send information, exchange information, capture measurements, etc. The specific I / O device interface 606 included in a particular machine will depend on the type of machine. It should be understood that the I / O device interface 606 and the I / O devices 646 may include various interfaces to the I / O devices 646 that are used by the machine 600 to receive input, provide output, generate output, send information, exchange information, capture measurements, etc. Figure 6 6. In various examples, the I / O device interface 606 may include an output component interface 628 and an input component interface 632. The output component interface 628 may include an interface to a visual component (e.g., a display such as a plasma display panel (PDP), a light emitting diode (LED) display, a liquid crystal display (LCD), a projector, or a cathode ray tube (CRT)), an acoustic component (e.g., a speaker), a tactile component (e.g., a vibration motor, a resistance mechanism), other signal generators, etc. The input component interface 632 may include an interface to an alphanumeric input component (e.g., a keyboard, a touch screen configured to receive alphanumeric input, an optical keyboard, or other alphanumeric input component), a pointing-based input component (e.g., a mouse, a touchpad, a trackball, a joystick, a motion sensor, or other pointing instrument), a tactile input component (e.g., a physical button, a touch screen that provides the location and / or force of a touch or touch gesture, or other tactile input component), an audio input component (e.g., a microphone), etc.

[0078] In another example, the I / O device interface 606 may include a biometric component interface 634, a motion component interface 636, an environmental component interface 638, or a positioning component interface 640, as well as various other component interfaces. For example, the biometric component interface 634 may include an interface to a component for detecting expressions (e.g., hand expressions, facial expressions, voice expressions, body postures, or eye tracking), measuring biosignals (e.g., blood pressure, heart rate, body temperature, perspiration, or brain waves), identifying a person (e.g., voice recognition, retinal recognition, facial recognition, fingerprint recognition, or EEG-based recognition), etc. The motion component interface 636 may include an interface to an IMU, an acceleration sensor component (e.g., an accelerometer), a gravity sensor component, a rotation sensor component (e.g., a gyroscope), etc. The environmental component interface 638 may include, for example, an interface to an illumination sensor component (e.g., a photometer), a temperature sensor component (e.g., one or more thermometers that detect ambient temperature), a humidity sensor component, a pressure sensor component (e.g., a barometer), an acoustic sensor component (e.g., one or more microphones that detect background noise), a proximity sensor component (e.g., an infrared sensor that detects nearby objects), a gas sensor (e.g., a gas detection sensor that detects concentrations of hazardous gases for safety or measures pollutants in the atmosphere), or other components that can provide indications, measurements, or signals associated with the surrounding physical environment. The positioning component interface 640 includes an interface to a position sensor component (e.g., a GPS receiver component), an altitude sensor component (e.g., an altimeter or barometer that detects air pressure, from which altitude can be derived), an orientation sensor component (e.g., a magnetometer), etc.

[0079] Communication can be achieved using various technologies. The I / O device interface 606 also includes a communication component interface 642 that is operable to couple the machine 600 to the network 622 or the device 624 via the coupling 630 and the coupling 626, respectively. For example, the communication component interface 642 may include an interface to a network interface component or another suitable device that interfaces with the network 622. In other examples, the communication component interface 642 may include an interface to a wired communication component, a wireless communication component, a cellular communication component, a near field communication (NFC) component, Components (e.g. Low energy consumption), Device 624 may be another machine or any of a variety of peripheral devices (eg, a peripheral device coupled via USB).

[0080] In addition, the communication component interface 642 may include an interface to a component that is operable to detect an identifier. For example, the communication component interface 642 may include an interface to a radio frequency identification (RFID) tag reader component, an NFC smart tag detection component, an optical reader component (e.g., an optical sensor for detecting one-dimensional bar codes such as a Universal Product Code (UPC) bar code; multi-dimensional bar codes such as a Quick Response (QR) code, an Aztec code, a Data Matrix, a Dataglyph, a MaxiCode, a PDF417, a Supercode, a UCC RSS-2D bar code, and other optical codes) or an acoustic detection component (e.g., a microphone for identifying an audio signal of a tag). In addition, various information may be obtained via the communication component interface 642, such as location via Internet Protocol (IP) geolocation, location information via RFID tags, and information about the location of the item. Location derived from signal triangulation, location derived via detection of NFC beacon signals that can indicate a specific location, etc.

[0081] Various memories (e.g., memory 604, main memory 614, static memory 616, and / or memory of processor 602) and / or storage unit 618 may store one or more sets of instructions and data structures (e.g., software) that embody any one or more of the methods or functions described herein or used by the methods or functions. These instructions (e.g., instructions 610), when executed by processor 602, cause various operations to implement the disclosed examples.

[0082] Instructions 610 may be sent or received over network 622 via a network interface device (e.g., a network interface component included in communication component interface 642) using a transmission medium and using any of several well-known transmission protocols (e.g., Hypertext Transfer Protocol (HTTP)). Similarly, instructions 610 may be sent or received via a coupling 626 (e.g., a peer-to-peer coupling) with device 624 using a transmission medium.

[0083] Figure 7is a block diagram showing a networked system 700 including details of a head-mounted AR device 100 according to some examples. The networked system 700 includes the head-mounted AR device 100, a client device 726, and a server system 732. The client device 726 can be a smartphone, a tablet computer, a tablet phone, a laptop computer, an access point, or any other such device capable of connecting to the head-mounted AR device 100 using a low-power wireless connection 736 and / or a high-speed wireless connection 734. The client device 726 is connected to the server system 732 via a network 730. The network 730 can include any combination of wired and wireless connections. The server system 732 can be one or more computing devices that are part of a service or network computing system. The client device 726 and any elements of the server system 732 and the network 730 can be configured using the respective Figure 8 and Figure 6 The details of the software architecture 804 or machine 600 described in are implemented.

[0084] The head-mounted AR device 100 includes a data processor 702, a display 710, one or more imaging devices 708, and additional input / output elements 716. The input / output elements 716 may include microphones, audio speakers, biometric sensors, additional sensors, pressure or force sensors, or additional display elements integrated with the data processor 702. Figure 8 and Figure 6 Examples of input / output elements 716 are further discussed. For example, input / output elements 716 may include any of the I / O device interfaces in I / O device interfaces 606, including output component interface 628, motion component interface 636, etc. Figure 2 Examples of display 710 are discussed in . In the particular examples described herein, display 710 includes displays for the user's left and right eyes.

[0085] Data processor 702 includes an image processor 706 (eg, a video processor), a GPU and display driver 738, an inertial motion unit 740, an interface 712, low-power circuitry 704, and high-speed circuitry 720. The components of data processor 702 are interconnected by a bus 742.

[0086] Interface 712 refers to any source of user commands provided to data processor 702. In one or more examples, interface 712 is a physical button that, when pressed, sends a user input signal from interface 712 to low-power processor 714. Pressing such a button and then immediately releasing it can be processed by low-power processor 714 as a request to capture a single image, and vice versa. Pressing such a button for a first period of time can be processed by low-power processor 714 as a request to capture video data while the button is pressed and to stop video capture when the button is released, wherein the video captured while the button is pressed is stored as a single video file. Alternatively, pressing the button for an extended period of time can capture a still image. In some examples, interface 712 can be any mechanical switch or physical interface capable of accepting user input associated with a request for data from imaging device 708. In other examples, interface 712 can have a software component or can be associated with a command received wirelessly from another source (e.g., from client device 726).

[0087] The image processor 706 includes circuitry for receiving signals from the imaging device 708 and processing those signals from the imaging device 708 into a format suitable for storage in the memory 724 or for transmission to the client device 726. In one or more examples, the image processor 706 (e.g., a video processor) includes a microprocessor integrated circuit (IC) customized for processing sensor data from the imaging device 708, and volatile memory used by the microprocessor in operation.

[0088] The low power circuit system 704 includes a low power processor 714 and a low power wireless circuit system 718. These elements of the low power circuit system 704 can be implemented as separate elements, or can be implemented as part of a single system on a chip on a single IC. The low power processor 714 includes logic for managing other elements of the head mounted AR device 100. As described above, for example, the low power processor 714 can accept user input signals from the interface 712. The low power processor 714 can also be configured to receive input signals or instruction communications from the client device 726 via the low power wireless connection 736. The low power wireless circuit system 718 includes circuit elements for implementing a low power wireless communication system. Also known as Bluetooth TM Bluetooth Low Energy TM Smart is a standard implementation of a low power wireless communication system that can be used to implement low power wireless circuitry 718. In other examples, other low power communication systems can be used.

[0089] High-speed circuitry 720 includes a high-speed processor 722, memory 724, and high-speed wireless circuitry 728. High-speed processor 722 can be any processor capable of managing the operation and high-speed communications of any general-purpose computing system for data processor 702. High-speed processor 722 includes processing resources for managing high-speed data transmission over high-speed wireless connection 734 using high-speed wireless circuitry 728. In some examples, high-speed processor 722 executes an operating system such as the LINUX operating system or a program such as the UNIX operating system. Figure 8 The high-speed processor 722, which executes the software architecture for the data processor 702, is used to manage data transmission with the high-speed wireless circuit system 728, in addition to any other responsibilities. In some examples, the high-speed wireless circuit system 728 is configured to implement the Institute of Electrical and Electronics Engineers (IEEE) 802.11 communication standard, also referred to herein as Wi-Fi. In other examples, other high-speed communication standards can be implemented by the high-speed wireless circuit system 728.

[0090] The memory 724 comprises any storage device capable of storing imaging device data generated by the imaging device 708 and the image processor 706. Although the memory 724 is shown as being integrated with the high-speed circuitry 720, in other examples, the memory 724 may be a separate, independent element of the data processor 702. In some such examples, electrical wiring may provide a connection from the image processor 706 or the low-power processor 714 to the memory 724 through a chip that includes the high-speed processor 722. In other examples, the high-speed processor 722 may manage addressing of the memory 724 so that the low-power processor 714 will initiate the high-speed processor 722 whenever a read or write operation involving the memory 724 is required.

[0091] The inertial motion unit 740 estimates the physical orientation or pose of the head-mounted AR device 100. For example, the inertial motion unit 740 uses image data from the imaging device 708 and associated inertial data determined using the positioning component interface 640, as well as GPS data, to track the position and determine the pose of the head-mounted AR device 100 relative to a reference frame (e.g., a real-world scene). The inertial motion unit 740 continuously collects and uses updated sensor data describing the movement of the head-mounted AR device 100 to determine an updated three-dimensional pose of the head-mounted AR device 100, which indicates changes in relative position and orientation relative to physical objects in the real-world scene. The inertial motion unit 740 allows the head-mounted AR device 100 to visually place virtual objects relative to physical objects within the user's field of view via the display 710.

[0092] When the head-mounted AR device 100 operates in conventional augmented reality mode, the GPU and display driver 738 can use the pose of the head-mounted AR device 100 to generate frames of virtual content or other content to be presented on the display 710. In this mode, the GPU and display driver 738 generate updated frames of virtual content based on the updated three-dimensional pose of the head-mounted AR device 100, which reflects changes in the position and orientation of the user relative to physical objects in the user's view of the real-world scene.

[0093] One or more functions or operations described herein may also be performed in an application residing on the head-mounted AR device 100, on the client device 726, or on a remote server. For example, one or more functions or operations described herein may be performed by one of the applications 806, such as the messaging application 846.

[0094] Figure 8 8 is a block diagram 800 illustrating a software architecture 804 that can be installed on any one or more of the devices described herein. The software architecture 804 is supported by hardware such as a machine 802 including a processor 820, a memory 826, and an I / O component interface 838. In this example, the software architecture 804 can be conceptualized as a stack of layers, where each layer provides specific functionality. The software architecture 804 includes layers such as an operating system 812, a library 808, a framework 810, and an application 806. In operation, the application 806 invokes an API call 850 through the software stack and receives a message 852 in response to the API call 850.

[0095] The operating system 812 manages hardware resources and provides common services. The operating system 812 includes, for example, a kernel 814, services 816, and drivers 822. The kernel 814 serves as an abstraction layer between the hardware and other software layers. For example, the kernel 814 provides functions such as memory management, processor management (e.g., scheduling), component management, networking, and security settings. Services 816 can provide other common services to other software layers. Drivers 822 are responsible for controlling or interfacing with the underlying hardware. For example, drivers 822 may include display drivers, imaging device drivers, or Low-power drivers, flash drives, serial communication drivers (e.g., Universal Serial Bus (USB) drivers), drivers, audio drivers, power management drivers, etc.

[0096] The library 808 provides a low-level common infrastructure used by the application 806. The library 808 may include a system library 818 (e.g., a C standard library) that provides functions such as memory allocation functions, string manipulation functions, mathematical functions, etc. In addition, the library 808 may include an API library 824, such as a media library (e.g., a library for supporting the presentation and manipulation of various media formats, such as Moving Picture Experts Group 4 (MPEG4), Advanced Video Coding (H.264 or AVC), Moving Picture Experts Group Layer-3 (MP3), Advanced Audio Coding (AAC), Adaptive Multi-Rate (AMR) audio codec, Joint Photographic Experts Group (JPEG or JPG), or Portable Network Graphics (PNG)), a graphics library (e.g., an OpenGL framework for rendering two-dimensional (2D) and three-dimensional (3D) graphics content on a display, GLMotif for implementing a user interface), an image feature extraction library (e.g., OpenIMAJ), a database library (e.g., SQLite for providing various relational database functions), a web library (e.g., WebKit for providing web browsing functions), etc. The library 808 may also include a variety of other libraries 828 to provide many other APIs to the application 806 .

[0097] The framework 810 provides a high-level common infrastructure used by the applications 806. For example, the framework 810 provides various graphical user interface (GUI) functions, high-level resource management, and high-level location services. The framework 810 can provide a wide range of other APIs used by the applications 806, some of which may be specific to a particular operating system or platform.

[0098] In an example, applications 806 may include a home application 836, a contacts application 830, a browser application 832, a book reader application 834, a location application 842, a media application 844, a messaging application 846, a game application 848, and a broad category of other applications, such as third-party applications 840. Applications 806 are programs that perform functions defined in the program. Various programming languages ​​may be used to create one or more of the variously structured applications 806, such as an object-oriented programming language (e.g., Objective-C, Java, or C++) or a procedural programming language (e.g., C or assembly language). In a specific example, third-party applications 840 (e.g., those written by entities other than the vendor of a particular platform using ANDROID) may be used to create a third-party application 840. TM or IOS TM Software Development Kit (SDK) can be used to develop applications on (such as IOS TM ANDROID TM 、 Mobile software running on the mobile operating system of the Phone or another mobile operating system. In this example, third-party applications 840 can activate API calls 850 provided by the operating system 812 to facilitate the functions described herein.

[0099] Figure 9 is a block diagram illustrating an example messaging system 900 for exchanging data (e.g., messages and associated content) over a network. The messaging system 900 includes multiple instances of client devices 726 that host several applications, including a messaging client 902 and other applications 904. The messaging client 902 is communicatively coupled to other instances of the messaging client 902 (e.g., hosted on respective other client devices 726), a messaging server system 906, and a third-party server 908 via a network 730 (e.g., the Internet). The messaging client 902 can also communicate with the locally hosted applications 904 using an application programming interface (API).

[0100] The messaging client 902 is able to communicate and exchange data with other messaging clients 902 and a messaging server system 906 via the network 730. The data exchanged between the messaging clients 902 and between the messaging clients 902 and the messaging server system 906 includes functions (e.g., commands for activating functions) and payload data (e.g., text, audio, video, or other multimedia data).

[0101] The messaging server system 906 provides server-side functionality to specific messaging clients 902 via the network 730. Although some functionality of the messaging system 900 is described herein as being performed by either the messaging client 902 or the messaging server system 906, the location of some functionality within the messaging client 902 or within the messaging server system 906 may be a design choice. For example, it may be technically preferable to initially deploy some technologies and functionality within the messaging server system 906 but later migrate such technologies and functionality to the messaging client 902, where the client device 726 has sufficient processing power.

[0102] The messaging server system 906 supports various services and operations provided to the messaging clients 902. Such operations include sending data to the messaging clients 902, receiving data from the messaging clients 902, and processing data generated by the messaging clients 902. By way of example, this data may include message content, client device information, geographic location information, media enhancements and overlays, message content persistence conditions, social network information, and live event information. Data exchange within the messaging system 900 is initiated and controlled by functionality available through the user interface (UI) of the messaging clients 902.

[0103] Turning now specifically to the messaging server system 906, an application program interface (API) server 910 is coupled to an application server 914 and provides a programming interface to the application server 914. The application server 914 is communicatively coupled to a database server 916, which facilitates access to a database 920 that stores data associated with messages processed by the application server 914. Similarly, a web server 924 is coupled to the application server 914 and provides a web-based interface to the application server 914. To this end, the web server 924 handles incoming network requests via the Hypertext Transfer Protocol (HTTP) and several other related protocols.

[0104] The application program interface (API) server 910 receives and sends message data (e.g., commands and message payloads) between the client device 726 and the application server 914. Specifically, the application program interface (API) server 910 provides a set of interfaces (e.g., routines and protocols) that can be called or queried by the messaging client 902 to activate the functions of the application server 914. The application program interface (API) server 910 exposes various functions supported by the application server 914, including: account registration; login functionality; sending messages from a particular messaging client 902 to another messaging client 902 via the application server 914; sending media files (e.g., images or videos) from a messaging client 902 to the messaging server 912 for possible access by another messaging client 902; setting up collections of media data (e.g., stories); retrieving a friend list of a user of the client device 726; retrieving such collections; retrieving messages and content; adding and removing entities (e.g., friends) to an entity graph (e.g., a social graph); locating friends in a social graph; and opening application events (e.g., related to the messaging client 902).

[0105] The application server 914 hosts several server applications and subsystems, including, for example, a messaging server 912, an image processing server 918, and a social network server 922. The messaging server 912 implements several message processing technologies and functions, particularly those related to the aggregation and other processing of content (e.g., text and multimedia content) included in messages received from multiple instances of the messaging client 902. As will be described in further detail, text and media content from multiple sources can be aggregated into collections of content (e.g., referred to as stories or galleries). These collections are then available to the messaging client 902. Given the hardware requirements for other processor- and memory-intensive processing of data, such processing can also be performed on the server side by the messaging server 912.

[0106] The application server 914 also includes an image processing server 918 that is dedicated to performing various image processing operations, typically on images or videos within the payload of messages sent from or received at the messaging server 912 .

[0107] The social network server 922 supports various social networking functions and services and makes these functions and services available to the messaging server 912. To this end, the social network server 922 maintains and accesses an entity graph within the database 920. Examples of functions and services supported by the social network server 922 include identifying other users of the messaging system 900 who have relationships with a particular user or who the particular user is "following," as well as identifying interests and other entities of a particular user.

[0108] The messaging client 902 can notify the user of the client device 726 or other users related to such user (e.g., "friends") of activities taking place in a shared or shareable session. For example, the messaging client 902 can provide participants in a conversation (e.g., a chat session) in the messaging client 902 with notifications related to current or recent use of a game by one or more members of a user group. One or more users can be invited to join an active session or initiate a new session. In some examples, a shared session can provide a shared augmented reality experience in which multiple people can collaborate or participate.

[0109] "Carrier signal" means any intangible medium that can store, encode, or carry instructions for execution by a machine, and includes digital or analog communications signals or other intangible media that facilitates communication of such instructions. Instructions may be sent or received over a network using a transmission medium via a network interface device.

[0110] "Client device" refers to any machine that interfaces with a communications network to obtain resources from one or more server systems or other client devices. A client device may be, but is not limited to, a mobile phone, desktop computer, laptop computer, portable digital assistant (PDA), smartphone, tablet computer, ultrabook, netbook, laptop computer, multiprocessor system, microprocessor-based or programmable consumer electronics, game console, set-top box, or any other communications device that a user may use to access a network.

[0111] "Communications network" means one or more parts of a network, which may be an ad hoc network, an intranet, an extranet, a virtual private network (VPN), a local area network (LAN), a wireless LAN (WLAN), a wide area network (WAN), a wireless WAN (WWAN), a metropolitan area network (MAN), the Internet, a part of the Internet, a part of the Public Switched Telephone Network (PSTN), a Plain Old Telephone Service (POTS) network, a cellular telephone network, a wireless network, The method of claim 10 further includes providing a method for transmitting data to a user of the network, the method of claim 10 , wherein the method comprises transmitting data to a user of the network, the method of claim 10 , and the method of claim 10 . The method of claim 10 , wherein the ...

[0112] "Machine-readable media" refers to both machine storage media and transmission media. Thus, the term encompasses both storage devices / medium and carrier / modulated data signals. The terms "machine-readable medium," "machine-readable medium," and "device-readable medium" mean the same thing and may be used interchangeably in this disclosure.

[0113] “Machine storage medium” refers to a single or multiple storage devices and / or media (e.g., a centralized or distributed database, and / or associated caches and servers) that store executable instructions, routines, and / or data. The term includes, but is not limited to, solid-state memory and optical and magnetic media, including memory internal or external to the processor. Specific examples of machine storage media, computer storage media, and / or device storage media include: non-volatile memory, including, for example, semiconductor memory devices such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), FPGAs, and flash memory devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The terms “machine storage medium,” “device storage medium,” and “computer storage medium” mean the same thing and may be used interchangeably in this disclosure. The terms “machine storage medium,” “computer storage medium,” and “device storage medium” expressly exclude carrier waves, modulated data signals, and other such media, at least some of which are encompassed under the term “signal media.”

[0114] A "processor" refers to any circuit or virtual circuit (a physical circuit emulated by logic executed on an actual processor) that manipulates data values ​​according to control signals (e.g., "commands," "opcodes," "machine code," etc.) and produces associated output signals that are used to operate a machine. For example, a processor may be a central processing unit (CPU), a reduced instruction set computing (RISC) processor, a complex instruction set computing (CISC) processor, a graphics processing unit (GPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a radio-frequency integrated circuit (RFIC), or any combination thereof. A processor may also be a multi-core processor having two or more independent processors (sometimes referred to as "cores") that can execute instructions simultaneously.

[0115] "Signal medium" refers to any intangible medium that is capable of storing, encoding, or carrying instructions for execution by a machine, and includes digital or analog communication signals or other intangible media that facilitate the communication of software or data. The term "signal medium" may be taken to include any form of modulated data signal, carrier wave, etc. The term "modulated data signal" means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. The terms "transmission medium" and "signal medium" mean the same thing and may be used interchangeably in this disclosure.

[0116] Changes and modifications may be made to the disclosed examples without departing from the scope of the present disclosure. These and other changes or modifications are intended to be included within the scope of the present disclosure as expressed in the following claims.

Claims

1. A computer-implemented method comprising: capturing, by the one or more processors, tracking video frame data of a real-world scene using one or more imaging devices of an augmented reality (AR) system; measuring, by one or more processors, strain data of a strain of a frame of the AR system using one or more strain gauges of the AR system as the tracking video frame data is captured; generating, by the one or more processors, a corrected frame model of the frame based on the strain data, the tracking video frame data, and the frame model of the frame; as well as Corrected tracking data is generated by the one or more processors based on the corrected frame model and the tracking video frame data.

2. The computer-implemented method of claim 1 , further comprising: generating, by the one or more processors, virtual overlay data based on the corrected tracking data; generating, by the one or more processors, corrected virtual overlay video frame data based on the corrected frame model and the virtual overlay data; as well as A virtual overlay is provided to a user of the AR system based on the corrected virtual overlay video frame data using an optical engine of the AR system by the one or more processors.

3. The computer-implemented method of claim 1 , wherein: The operation of generating a corrected frame model of the frame further includes: generating visual-inertial odometry data based on the tracking video frame data, the strain data, and the frame model; and The corrected frame model is generated based on the visual-inertial odometry data and the frame model.

4. The computer-implemented method of claim 3, wherein: The operation of generating the visual inertial odometry data further includes: generating yaw bending data of the frame based on the strain data; and The visual-inertial odometry data is generated based on the tracking video frame data, the yaw bending data, and the frame model.

5. The computer-implemented method of claim 3, wherein: The operation of generating the visual inertial odometry data further includes: measuring, by the one or more processors, inertial movement data of the frame using an inertial measurement unit of the frame as the tracking video frame data is captured; generating initial inertial odometry data based on the inertial movement data; and The visual inertial odometry data is generated based on the initial inertial odometry data, the tracking video frame data, the strain data, and a frame-of-frame model of the frame.

6. The computer-implemented method of claim 1 , wherein: At least one of the one or more strain gauges is mounted on a bridge portion of the frame.

7. The computer-implemented method of claim 1 , wherein: The AR system includes a head-mounted AR device.

8. An AR system comprising: frame; one or more strain gauges operable to measure strain of the frame; one or more imaging devices mounted to the frame; one or more processors; as well as A memory storing instructions that, when executed by the one or more processors, cause the AR system to perform operations including: capturing tracking video frame data of a real-world scene using the one or more imaging devices; measuring, by one or more processors, strain data of a strain of a frame of the AR system using one or more strain gauges of the AR system as the tracking video frame data is captured; generating, by the one or more processors, a corrected frame model of the frame based on the strain data, the tracking video frame data, and the frame model of the frame; as well as Corrected tracking data is generated by the one or more processors based on the corrected frame model and the tracking video frame data.

9. The AR system according to claim 8, wherein: The AR system further includes an optical engine mounted to the frame, and When the instructions are executed by the one or more processors, the AR system further causes the AR system to perform the following operations: generating virtual overlay data based on the corrected tracking data; generating corrected virtual overlay video frame data based on the corrected frame model and the virtual overlay data; and Using the optical engine, a virtual overlay is provided to a user of the AR system based on the corrected virtual overlay video frame data.

10. The AR system according to claim 8, wherein: The instructions, which when executed by the one or more processors cause the AR system to perform operations of generating a corrected frame model of the frame, further cause the AR system to perform operations including: generating visual-inertial odometry data based on the tracking video frame data, the strain data, and the frame model; and The corrected frame model is generated based on the visual-inertial odometry data and the frame model.

11. The AR system according to claim 10, wherein: The instructions, when executed by the one or more processors, cause the AR system to perform operations of generating the visual-inertial odometry data further cause the AR system to perform operations including: generating yaw bending data of the frame based on the strain data; as well as The visual-inertial odometry data is generated based on the tracking video frame data, the yaw bending data, and the frame model.

12. The AR system according to claim 11, wherein: The instructions, which when executed by the one or more processors cause the AR system to perform operations including generating the visual-inertial odometry data, further cause the AR system to perform operations including: determining, by the one or more processors, inertial movement data for the frame using an inertial measurement unit of the frame as the tracking video frame data is captured; generating initial inertial odometry data based on the inertial movement data; and The visual inertial odometry data is generated based on the initial inertial odometry data, the tracking video frame data, the strain data, and a frame-of-frame model of the frame.

13. The AR system according to claim 8, wherein: At least one of the one or more strain gauges is mounted on a bridge portion of the frame.

14. The AR system according to claim 8, wherein: The AR system includes a head-mounted AR device.

15. A non-transitory computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform operations comprising: capturing, using one or more imaging devices of the AR system, tracking video frame data of the real-world scene; measuring, by one or more processors, strain data of a strain of a frame of the AR system using one or more strain gauges of the AR system as the tracking video frame data is captured; generating, by the one or more processors, a corrected frame model of the frame based on the strain data, the tracking video frame data, and the frame model of the frame; as well as Corrected tracking data is generated by the one or more processors based on the corrected frame model and the tracking video frame data.

16. The non-transitory computer-readable storage medium of claim 15, wherein: When the instructions are executed by the computer, the computer further performs the following operations: generating virtual overlay data based on the corrected tracking data; generating corrected virtual overlay video frame data based on the corrected frame model and the virtual overlay data; as well as A virtual overlay is provided to a user of the AR system based on the corrected virtual overlay video frame data using an optical engine of the AR system.

17. The non-transitory computer-readable storage medium of claim 15, wherein: The instructions, which when executed by the computer cause the computer to perform operations of generating a corrected frame model of the frame, further cause the computer to perform operations comprising: generating visual-inertial odometry data based on the tracking video frame data, the strain data, and the frame model; and The corrected frame model is generated based on the visual-inertial odometry data and the frame model.

18. The non-transitory computer-readable storage medium of claim 17, wherein: The instructions, when executed by the computer, that cause the computer to perform operations of generating the visual-inertial odometry data further cause the computer to perform operations comprising: generating yaw bending data of the frame based on the strain data; as well as The visual-inertial odometry data is generated based on the tracking video frame data, the yaw bending data, and the frame model.

19. The non-transitory computer-readable storage medium of claim 18, wherein: The instructions, when executed by the computer, cause the computer to perform operations including generating the visual-inertial odometry data, further cause the computer to perform operations including: determining inertial motion data for the frame using an inertial measurement unit of the frame as the tracking video frame data is captured; generating initial inertial odometry data based on the inertial movement data; and The visual inertial odometry data is generated based on the initial inertial odometry data, the tracking video frame data, the strain data, and a frame-of-frame model of the frame.

20. The non-transitory computer-readable storage medium of claim 15, wherein: The AR system includes a head-mounted AR device.

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