System and method for reducing cyber-discomfort

Abstract

A system and method for reducing cyber-discomfort (12) for navigation in an immersive virtual environment (2) is proposed, comprising a control unit (7), a virtual environment (2) displayed on a display system (3), a position-capture system (6) for the user's physical viewpoint (4), and a navigation system (9) that moves the user's virtual viewpoint within the virtual environment. The movements of the user's virtual viewpoint relative to the virtual environment, generated by the navigation system (9), and the actual rotations of the user's physical viewpoint relative to the real world (11) are monitored. Incentives for rotations of the user's physical viewpoint relative to the real world (11) are determined.Rotation prompts relate to at least partial corrections of discrepancies and / or inconsistencies between the movements from the virtual viewpoint and the actual rotations from the user's physical viewpoint. A pre-positioned visual reference (10) in the virtual visual environment is modified in real time according to the rotation prompts. Abstract figure: Figure 4b.

Description

Title of the invention: System and method for reducing cyber-discomfort Technical field

[0001] The present disclosure relates to a cyber-discomfort reduction system, a corresponding method, a computer program and a storage medium. The present invention aims to induce a physical head movement of the user, so as to reduce or eliminate the visuo-vestibular conflict, by the real-time use of a deformation-driven indicator object. Prior art

[0002] One of the essential tasks that a user can perform in a virtual environment is movement, also called navigation. The physical environment in which he finds himself is generally more restricted than the virtual environment, the user must then use one or more navigation methods.

[0003] Navigation is subject to the phenomenon called cyber-sickness or simulator sickness, which manifests itself by symptoms of discomfort, headaches or dizziness, sometimes even vomiting. This movement can be done, for example, by using joysticks from an immersive room, called a CAVE, or by being equipped with a head-mounted display, or in a driving or flight simulator. Whether navigation is carried out in a CAVE, in a simulator, using a 3D television or a 3D projection system, or equipped with a Virtual Reality (VR), Augmented Reality (AR) or Mixed Reality (MR) head-mounted display, and whether for the purpose of training, research, industrial design or in the field of gaming, the phenomenon of cyber-sickness is encountered by a large number of users, making experimentation difficult, unrepresentative or sometimes interrupting the exercise.

[0004] In the case where the display system used to view the virtual environment occupies a small visual field in a real environment, for example in the case of AR, the field of vision of the player or user is sufficiently small so as not to immerse him totally, keeping his external visual references. Said user is therefore less subject to said nausea.

[0005] Conversely, a user navigating in an immersive virtual environment, such as in a CAVE or with a virtual or augmented reality headset, is frequently subject to cyber-sickness, or simulator sickness in the case of a simulator. One of the main reasons is that the movement perceived visually during virtual movement conflicts with the movement perceived by the vestibular system. The movement most likely to cause simulator sickness is rotation (for example example when maneuvering in a turn - yaw and / or roll, but also when braking - pitching). Indeed, the brain of the user accustomed to moving in the real world expects to receive acceleration and speed measurements from his vestibular system of the inner ear, more precisely from the semicircular canals, consistent with those estimated by the visual system. In the absence of restitution of these physical effects by an adequate system, such as for example a dynamic driving or flight simulator, the brain triggers symptoms resembling those of motion sickness. In the real world, during travel, visual and vestibular information are generally consistent but inconsistent information can also be perceived. This is the case of motion sickness, not for the driver, but for a passenger, who cannot anticipate movements, especially if he is not looking outside.This case is similar to that of a virtual environment. If the passenger looks outside, the probability of motion sickness is reduced. In an immersive virtual environment, particularly in a CAVE or equipped with a head-mounted display, the modification of the visual environment during navigation is dissociated from the physical movement of the user and can therefore generate simulator sickness.

[0006] Simulator sickness is well known in the field of virtual environments. To reduce simulator sickness, it is known to reassociate visual perception with physical movement.

[0007] There are two main categories of means for moving around in a virtual environment.

[0008] Motion compensation devices allow the user to move naturally without having to trigger commands. The omnidirectional Cyberwalk treadmill or the Cybersphere are examples, and there are many other systems (hemispherical ball carpet, moving tile network, active shoes, robot arms attached to the feet, etc.). Most of these devices have the disadvantage of being bulky or intrusive, and poorly suited to general public use. In addition, most are only suitable for natural movements of the observer, without being able to use navigation systems, for example a vehicle or any simulated artificial system.

[0009] Navigation processes are laws for controlling devices that often already exist (controllers, virtual reality gloves, etc.) that modify the movement process used in real life, allowing for rapid learning and easy use. There are several, for example walking on the spot, which consists of mimicking walking to move forward. Redirected walking on the spot is a solution to the immersion problems due to the missing faces of the CAVE; it rotates the environment imperceptibly so that the user never has to orient themselves towards the missing face. The virtual companion is a virtual animal controlled by reins, it pulls the user and allows rotations.

[0010] For example, "Grabbing the Air" is a navigation method in which the user can grab the air with his hand, bring it back towards him to scroll through the scenery, and make a lateral movement to make it rotate around him. A disadvantage of this system is that it does not reduce simulator sickness because the user's brain does not receive information from his vestibular system that is consistent with that estimated by the visual system.

[0011] Publication US-AÏ 2004 / 0102676 thus discloses a system for coupling the visual environment and navigation in order to reduce motion sickness. Said system requires several hardware devices such as a gyroscope, accelerometers, a positioning system known as GPS or "Global Positioning System" in English, optical sensors and vibration sensors and several software programs to reduce said motion sickness.

[0012] A disadvantage of the disclosed system is the need to use many hardware devices, which results in high costs as well as sophisticated control of all the devices.

[0013] Patent publication No. FR3025645 - 1458421 makes it possible to break down a rotational movement into two movements, each of which is natural, and thus avoids generating motion sickness or cyber-sickness by proposing to first perform a movement that is both visual and physical in the virtual world and then a movement of the operator that is also both visual and physical. However, since this method is not natural, it cannot be used to perform rotations in a natural and understandable way for the operator.

[0014] Apart from the previously cited patent, the use of a navigation method generates a movement rendered only visually, and therefore generates a visuo-vestibular conflict potentially causing simulator sickness. For example, for a rotation to the right, a navigation method will generally use a rotation of the virtual environment to the left to render it. Summary

[0015] One aim of the invention is to remedy the effects of cyber-discomfort by supplementing or modifying a method of rotating navigation in an immersive virtual environment.

[0016] The subject of the invention relates to the reduction of cyber-discomfort for any virtual movement of the observer controlled by a navigation system which generates cyber-discomfort effects insofar as it generates a visuo-vestibular conflict. Said movement can be broken down into a linear movement and a rotational movement to which the invention relates.

[0017] The object of the invention is the reduction of cyber-sickness and simulator sickness for rotational movement, regardless of the axis of said rotation.

[0018] The object of the invention is therefore to provide a means of performing a rotational movement in an immersive virtual environment in an efficient, comfortable manner and without visuo-vestibular discomfort (cyber-sickness or simulator sickness).

[0019] The subject of the invention relates to the display and modification in real time of a visual reference during navigation in a virtual environment. Such a modification is designed to fulfill a visual incentive function making it possible to generate an involuntary rotation of the user's head, according to the commonly accepted hypothesis of stationarity of the surrounding world. During navigation in a virtual environment, this movement of the user's head, and possibly of the body, induced by the real-time modification according to the invention makes it possible to reduce or even eliminate the visuo-vestibular conflict and thus to reduce or even eliminate simulator sickness or "cybersickness" in English, or cyber-discomfort.

[0020] Definitions are now provided for various terms used in the remainder of this document.

[0021] The real world (or physical world) is the reference point of the room in which the user is physically located.

[0022] The user's physical point of view comprises the spatial coordinates of a point representative of the user's vision in the physical world; this point may be, for example, a midpoint arranged between the user's eyes.

[0023] The user's virtual environment (or virtual world) includes all the virtual elements that can be viewed by the user.

[0024] The user's virtual viewpoint comprises the spatial coordinates, in a virtual spatial reference frame, of a point representative of the user's vision in the virtual world. Translation and / or rotation operations may be implemented, for example at the user's initiative, in order to modify the spatial coordinates of the virtual viewpoint.

[0025] The user's virtual visual environment is the portion of the virtual environment displayed on the display system, corresponding to the user's virtual point of view deemed to be located at the origin of the virtual spatial reference.

[0026] The visual reference is a modifiable visual element such as a wireframe representation of a CAVE-type room, an arrow on the ground or any other type of visual reference or artifact that can be displayed superimposed on the virtual visual environment. It is possible to define, for the visual reference, an appearance, a shape and a reference orientation in the virtual world. The modification of the visual reference can be, for example, a modification of appearance, shape and / or orientation relative to this reference appearance, shape and / or orientation.

[0027] The modifiable virtual nose is a particular example of a visual reference that is attached to the embodiment of the user's head in the virtual world. The virtual nose may be displayed in a CAVE-type room, or through a virtual reality headset, or in any other virtual visual environment. Optionally, the virtual nose may have the following general structure: a base fixed relative to the user's virtual viewpoint and a body extending from the base and terminating in an end. The base may be displayed towards the bottom of the field of view in a region that corresponds, for example, in the physical world, to that of the user's nose. The virtual nose may be deformable, i.e., visual parameters of the virtual nose in the virtual environment, such as the position of the end, the shape of the body and / or the orientation of the body, may be made modifiable.The virtual nose may, for example, have a reference shape in which the body is rectilinear, associated with a reference orientation in which the position of the tip is such that the base-tip vector points toward a central direction of the virtual visual environment. In particular, the virtual nose may be configured to indicate the direction of movement, such that its realignment toward a reference direction (e.g., forward) indicates to the user that he or she does not need to turn his or her head. When the shape of the visual reference is modifiable, provision may be made, for example, to curve the body. When the orientation of the visual reference is modifiable, provision may be made to modify the position of the tip.When the appearance of the visual reference is modifiable, it may be possible to modify a degree of transparency and / or a color of the visual reference, or to display an emphasis mark at the edge of the visual reference.

[0028] The navigation method (or navigation system) is the means used by the user to trigger the modification of his virtual point of view in the virtual environment, whether by means of a physical device, a voice command or any action or movement of all or part of his body.

[0029] The present technique provides, through a system, a method and a computer program, different aspects of a visual procedure in the virtual world to induce voluntary movement of the user in the physical world by the use of an interactively modifiable element.

[0030] A system for reducing cyber-discomfort is thus proposed for navigation in an immersive virtual environment, comprising a control unit, a virtual visual environment, corresponding to a virtual point of view of the user, displayed on a display system, a system for capturing the position of the physical point of view of the user, and a navigation system moving the virtual point of view of the user in the virtual environment, said system being capable of: monitoring the movements of the user's virtual point of view relative to the virtual environment generated by the navigation system; monitor actual rotations from the user's physical perspective relative to the real world; determining rotation incentives from the user's physical point of view relative to the real world, the rotation incentives relating to at least partial corrections of deviations and / or discrepancies between the movements from the virtual point of view and the actual rotations from the user's physical point of view; and depending on the rotation incentives, modifying in real time a pre-positioned visual reference in the virtual visual environment.

[0031] It is understood that “the movements from the virtual point of view of the user in relation to the virtual environment” are likely to designate translational movements and / or rotational movements.

[0032] It is understood that a "rotation incentive" relates to a correction of a discrepancy currently observed between movements from the virtual point of view and actual rotations from the physical point of view of the user. The rotation incentive comprises at least one visual component which, when perceived by the user, is such as to induce an additional actual rotation from the physical point of view of the user, this additional actual rotation correcting, entirely or partially, the discrepancy currently observed.

[0033] It is understood that a “discordance” designates a qualitative difference. For example, a translational displacement of the virtual point of view to the left which is not accompanied by any rotation from the physical point of view represents a discordance, because the user visually perceives a displacement without simultaneously performing a physical rotation of the head or body. This discordance is thus the source of a visuo-vestibular conflict.

[0034] It is understood that a “deviation” designates a quantitative difference. For example, a rotation of the virtual point of view of 90° to the left which is accompanied by a rotation of the physical point of view of 10° to the left represents a significant deviation between the displacement visually perceived by the user and the actual rotation of his head or body. This deviation can be expressed here in the form of an angular difference equal to 80° and is also a source of visuo-vestibular conflict.

[0035] The same situation can be described as both a discordance and a deviation. For example, a rotation of the virtual point of view of 50° to the left which is accompanied by a rotation of the physical point of view of 10° to the right represents both a qualitative difference because the directions of rotation are opposite, and a quantitative angular difference equal to 60°.

[0036] Advantageously, the system is also capable of: performing a comparison between several predefined modification modes of the visual reference by means of a supervised learning model, on the basis of a respective evaluation of the user's tracking of the rotation recommendations when the visual reference is respectively modified according to each of the predefined modification modes, and choose, from the predefined editing modes, a custom editing mode for the user based on the comparison result.

[0037] Thus, it is possible, for example, to display the visual reference in its reference appearance, shape and orientation when the user's physical viewpoint and virtual viewpoint are aligned, within a predefined threshold of angular deviation, but to modify the visual reference when this deviation exceeds the predefined threshold. The modification may include a change in appearance, for example of color, and / or shape and / or orientation. This change may be progressive and a function of the amplitude of the angular deviation. Modifications of a different nature may be provided depending on the situation encountered.

[0038] For example, in a situation where the user's physical viewpoint remains unchanged during and / or following a translation of the virtual viewpoint forwards or backwards, provision may be made to modify the length of the visual reference and / or to make a slight change in orientation of the visual reference upwards or downwards, in the direction of a point located slightly above the horizon in the virtual environment.

[0039] Considering a situation where the user's physical viewpoint remains unchanged during and / or following a rotation of the user's virtual viewpoint to the right, provision may be made to distort the visual reference to the right, thereby causing a stimulus for the user. If the user reacts to the stimulus by rotating his or her head or body to the right, then provision may be made to modify the visual reference again so as to restore its reference appearance, shape and / or orientation.

[0040] Advantageously, monitoring the actual rotations from the user's physical point of view relative to the real world comprises collecting, by means of the position capture system from the user's physical point of view, time series indicative of angular parameters relating to the orientation of the user's head, the angular parameters including positions, speeds, accelerations and / or jolts.

[0041] Advantageously, the visual reference is modified according to a command linked to the navigation system and to the rotational movement of the user's head, thus the user's brain perceives information from his vestibular system consistent with that estimated by the visual system, which significantly reduces, or even eliminates the risk of simulator pain depending on the system response time.

[0042] The human brain has a plasticity that allows it to tolerate certain inconsistencies, in amplitudes and temporality. It is therefore not necessarily a question of coordinating and synchronizing rotations precisely (although we try to stick to it as closely as possible). The idea is to induce a "sufficient" head movement to allow the user to maintain visuo-vestibular coherence. Artificial intelligence means are mentioned in this document for various reasons, and in particular for the purpose of helping to stick as closely as possible to the user's perception and their perceptual characteristics.

[0043] Advantageously, at the start of the user's navigation in the virtual environment by means of the navigation system, the visual reference is preferably oriented aligned with respect to the user's physical point of view. Said visual reference may optionally not be displayed when the navigation system is not in use.

[0044] Advantageously, the visual reference is generated virtually and displayed with the virtual environment by the display system when the user uses the navigation system.

[0045] Advantageously, modifying the visual reference comprises modifying the shape, orientation and / or appearance of the visual reference.

[0046] Advantageously, during rotational navigation, the visual reference rotates in the desired direction so that the physical viewpoint also rotates in the same direction.

[0047] At the same time, the virtual world rotates in the opposite direction relative to the real world, reduced by all or part of the rotational movement from the physical point of view of the observer, due to the impact of the rotation of the visual reference.

[0048] The rotation speeds relative to the real world of the visual reference and the virtual world are advantageously controlled as a function of perceptual thresholds, the elapsed time, as well as the rotation speed from the physical point of view relative to the real world.

[0049] The rotation perceived by the user is that of his head relative to the virtual world, that is to say the accumulation of the rotation of the virtual world relative to the real world and the rotation of his head relative to the real world.

[0050] When the user stops using the navigation system, the visual reference stops and may no longer be displayed. The virtual world also stops relative to the real world. The rotation performed during navigation is the sum of the rotation of the virtual world relative to the real world and the rotation of the head relative to the real world.

[0051] Also provided is a method for reducing cyber-discomfort for navigation in an immersive virtual environment, the method being implemented by a system for reducing cyber-discomfort comprising a control unit, a virtual visual environment, corresponding to a virtual point of view of the user, displayed on a display system, a system for capturing the position of the physical point of view of the user, and a navigation system moving the virtual point of view of the user in the virtual environment, said method comprising: monitor the movements of the user's virtual point of view relative to the virtual environment generated by the navigation system; monitor actual rotations from the user's physical perspective relative to the real world; determining rotation incentives from the user's physical point of view relative to the real world, the rotation incentives relating to at least partial corrections of deviations and / or discrepancies between the movements from the virtual point of view and the actual rotations from the user's physical point of view; and depending on rotation incentives, modify in real time a pre-positioned visual reference in the virtual visual environment.

[0052] Advantageously, the proposed method comprises: a step of displaying a visual reference, a step of rotation of the visual reference linked to the navigation system, and to the orientation of the user's physical point of view in relation to the real world, a step of deactivation of the display of the visual reference.

[0053] According to the proposed technique, the display system can be stationary relative to the real world, as in most CAVE or immersive room type installations, or linked to the user's head, as in the case of a virtual or augmented reality headset. Brief description of the drawings

[0054] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which: Fig.l

[0055] [Fig.l] is a schematic view of an immersive room with a user navigating in a virtual environment. Fig. 2

[0056] [Fig.2] is a schematic top view illustrating an example of use of the invention with a CAVE type environment. Fig. 3

[0057] [Fig.3] is a schematic top view illustrating the use of the invention with a virtual or augmented reality headset. [Fig.2] and [Fig.3] illustrate references used for the description of the invention. Fig. 4a, 4b, 4c and 4d

[0058] [Fig.4a], [Fig.4b], [Fig.4c] and [Fig.4d] are schematic views of modification in rotation of the virtual environment and modification of the visual reference from the user's physical point of view. Description of the embodiments

[0059] In the following description, identical reference numerals designate identical parts or parts having similar functions.

[0060] According to [Fig.l] which presents an embodiment of the invention, a user (1) can navigate virtually in a virtual environment (2) broadcast on a display system (3). This display system (3) can comprise for example one screen for a “powerwall” type system, two screens for a “workbench” type system, three to 6 screens for a “CAVE” type system, or more generally one or more screens of any shape(s) for an immersive room. The display system (3) can also be an extended reality headset, namely virtual, augmented or mixed / fused reality.

[0061] The representation of the virtual environment (2) depends on the physical point of view (4) of the user (1) in relation to the real world (11), on the vision pyramid (5) according to which he views said representation, as well as on the position of the virtual point of view of the user. The physical point of view (4) of the user (1) is measured continuously, directly or indirectly, by a position capture system (6), such as for example cameras or an inertial unit.

[0062] The images broadcast on the display system (3) are generated by a control unit (7) connected to said display system as well as to the position capture system (6).

[0063] The user (1) may or may not be equipped with a pair of specific glasses (8) to allow him a stereoscopic perception of the virtual environment (2) on the display system (3), or any other relief visualization system.

[0064] A navigation system (9) allows the user (1) to move around in the virtual environment (2). This system can be activated by an external operator (not shown) or by the user (1) himself, by means of movements of all or part of his body and / or physical interfaces such as a controller, a joystick, a treadmill, a steering wheel or pedals for example.

[0065] Optionally, a system may be provided to control the generation and display of a user avatar. The avatar is displayed superimposed on the virtual environment (2) and is prepositioned relative to the user's physical point of view. The avatar is a representation of all or part of the user's body and can take the form of a character, an articulated skeleton, a head, a hand, or more generally any form, articulated or not, that the user could assimilate to a representation of his person in the virtual environment. The main function of the avatar is to transcribe in real time movements or gestures that the user makes in the physical world. There are many known avatar generation technologies for this purpose. These technologies can rely, for example, on position data such as those from the position capture system (6). Some known avatar generation and display technologies also rely on data from a device manipulated by the user.This may then be user interaction data with a physical interface of such a device and / or position data from position sensors integrated into such a device. This data is then used to generate a representation of the hand manipulating the device.

[0066] Finally, the invention provides a system for reducing cyber-discomfort, cybersickness or simulator sickness (12), which controls the display and modification of a visual reference (10), displayed superimposed on the virtual environment (2). Like the avatar described above, this visual reference (10) is prepositioned relative to the physical point of view of the user and can take, for example, the form of a vertical grid as in [Fig.l], an arrow on the ground or any other form, artifact or object, articulated or not. A virtual nose attached to the user's avatar, a whole or partial car cockpit, or an object held in a hand of the user's avatar, for example a rifle, a sword, a stick, etc. in a game, are all particular examples of visual reference.

[0067] The cyber-discomfort reduction system (12) is connected to the position capture system (6) and to the navigation system (9), which allows it to collect and monitor the temporal developments from the physical point of view and from the virtual point of view of the user. Depending on these temporal developments, the cyber-discomfort reduction system can determine (quantitative) deviations and / or (qualitative) discrepancies between the movements from the virtual point of view on the one hand and the rotations from the physical point of view on the other hand. The cyber-discomfort reduction system controls the changes in the visual reference in real time depending on these deviations and / or discrepancies.

[0068] Different modifications of the visual reference can be implemented. These can be modifications of shape, i.e. deformations, modifications of orientation, size, color, appearance, transparency, sharpness, etc. Several types of modifications of the visual reference can be implemented simultaneously, for example a deformation can be combined with a change of color.

[0069] The successive application in real time of such modifications has the effect of animating the visual reference by slaving, for example, its appearance or its current form to the discrepancies between the rotations from the physical point of view and the movements from the virtual point of view of the user.

[0070] [Fig.2] illustrates in top view a use of the invention with a CAVE type system. The virtual world (2) is represented by the hatched surface. The display system (3) of the CAVE is symbolized by the 3 strong lines, and the visual reference (10) is symbolized by the 3 dotted lines.

[0071] [Fig. 3] illustrates in top view a use of the invention with a virtual or augmented reality headset. As for [Fig. 2], the virtual world (2) is represented by the hatched surface, and the visual reference (10) is represented by the dotted lines.

[0072] According to Figures 2 and 3, several references can be used to describe and understand the operation of the invention.

[0073] “R real world” is the real world reference point (11), i.e. the reference point of the room physical environment in which the user is located.

[0074] “R virtual world” is the reference of the virtual environment (2) displayed by the display system (3).

[0075] “R head” is the reference point from the user’s physical point of view (1).

[0076] “R visual reference” is the reference linked to the visual reference (10) on which the including the invention.

[0077] Finally, “R display system” is the reference of the display system (3) on which the representation of the virtual environment is broadcast.

[0078] In most CAVE or immersive room type installations, the display system (3) is immobile relative to the real world (11). In this case, “R display system” and “R real world” are fixed relative to each other. When using a virtual or augmented reality headset, the display system (3) is linked to the user’s head (1), and therefore in this case it is “R display system” and “R head” which are immobile relative to each other. For the sake of clarity, “R display system” is therefore not shown in [Fig.3], being almost confused with “R head”.

[0079] Figures 4a, 4b, 4c and 4d represent examples of rotations in an extended reality headset type environment, using the navigation system (9) and the cyber-discomfort reduction system (12) according to an embodiment of the invention (12).

[0080] [Fig.4a] represents the user's virtual visual environment in an initial state before the rotation to the right. In the initial state, the user's head and the visual reference (10) are aligned, i.e. "R head" and "R visual reference" are aligned. In this initial state, the visual reference (10) may not be displayed. In [Fig.4a], the visual reference (10) is an elongated virtual nose having a base located towards the origin of the "R visual reference" reference, a straight body and a rounded end.

[0081] [Fig.4b] represents the virtual visual environment of the user in a current state, during the rotation to the right of the virtual point of view by means of the navigation system (9).

[0082] The speed of this rotation to the right is noted "virtual co-point of view". The virtual visual environment represented in [Fig.4b] has simultaneously undergone a rotation of the same speed in the opposite direction (to the left in this example) relative to the real world.

[0083] The rotation perceived by the user (1) is that of his head relative to the virtual world (2), i.e. the total of the rotation of the virtual world (2) relative to the real world (11) and the rotation of his head relative to the real world (11). It has been shown that the brain reacts mainly to the acceleration felt, and to a lesser extent to the speed of movement, as well as to the derivative of the acceleration or "jerk".

[0084] To avoid or at least limit the visuo-vestibular conflict, it is necessary that the movements from the virtual point of view correspond substantially to the movements from the physical point of view. In other words, it is necessary that, while the navigation system operates the rotation movement from the virtual point of view, the user performs a synchronized rotation movement from the physical point of view, in the same direction (here to the right).

[0085] The cyber-discomfort reduction system simultaneously monitors the movements of the virtual point of view operated by the navigation system and the rotations of the physical point of view simultaneously operated by the user.

[0086] Based on this monitoring, the cyber-discomfort reduction system is capable of determining at any time one or more values ​​relating to a felt movement, such as the felt movement speed, the felt acceleration and / or the felt jerk, and of applying a pre-established strategy for limiting or eliminating the visuo-vestibular conflict in order to:

[0087] choosing, on the basis of the value(s) relating to the felt movement, a target value of the rotation speed from the physical point of view and

[0088] modify the visual reference according to the difference between the target value and the currently recorded value of the rotation speed from the physical point of view.

[0089] In the example of [Fig.4b] it is considered that the value recorded at a current instant of the rotation speed from the physical point of view, noted “co physical point of view”, is lower than the target value determined by the cyber-reduction system. discomfort, noted as “co-target from a physical point of view”.

[0090] In [Fig.4b], the modification of the visual reference is a deformation: the body of the deformable nose becomes curved, which shifts the end to the right without the position of the base being significantly modified.

[0091] This distortion is perceived by the user, consciously or not, as an incentive to increase the speed of rotation of his head to the right to get closer to the target speed. The visuo-vestibular conflict is reduced, as is cyber-discomfort.

[0092] Generally speaking, the modification of the visual reference must be considered as being subject to a shift observed between a movement from the virtual point of view and a corresponding rotation from the physical point of view. This shift can be defined qualitatively and / or quantitatively.

[0093] This point can be illustrated by comparing three situations, all three beginning with the initial state associated with [Fig.4a] and ending with three distinct current states respectively associated with the examples in Figures 4b, 4c and 4d.

[0094] The first situation is associated with [Fig.4b] and concerns a rotational movement of the virtual point of view to the right associated with an insufficiently rapid rotation of the physical point of view to the right. In this first situation, the visual reference is slightly distorted, in real time during navigation in the virtual world, due to the gap between “co-physical point of view” and “co-target physical point of view”. This slight distortion is shown in [Fig.4b].

[0095] The second situation is associated with [Fig.4c] and concerns a rotation of the virtual point of view to the right associated with a sufficiently rapid rotation of the physical point of view to the right. In this second situation, the cyber-discomfort reduction system determines that the difference between “co-physical point of view” and “co-target physical point of view” is substantially zero or less than a predetermined threshold and does not implement any modification of the visual reference. In [Fig.4c], the visual reference is thus not distorted.

[0096] The third situation is associated with [Fig.4d] and concerns a significant discrepancy or gap between the movement of the virtual viewpoint (to the left) and the rotation of the physical viewpoint. Such a situation is likely to occur when

[0097] the movement of the virtual point of view is particularly rapid compared to the rotation of the physical point of view (significant difference), or

[0098] the movement from the virtual point of view is not accompanied by any rotation from the physical point of view (discordance), or

[0099] the rotation of the physical point of view is carried out in the opposite direction to that of the movement of the virtual point of view (discordance).

[0100] A significant difference is then obtained between “co physical point of view” and “co target physical point of view”, resulting in a large amplitude modification of the visual reference. Thus, for example, the visual reference is distorted more significantly in [Fig.4d] than in [Fig.4b]: the curvature of the body is more marked.

[0101] Figures 4a to 4d illustrate an application of a particular example of a pre-established strategy for limiting or eliminating visuo-vestibular conflict.

[0102] It should be emphasized that this strategy can be scalable and in particular personalized according to the user's particular sensitivity to the visuo-vestibular conflict and / or according to the user's receptivity to the modification of the visual reference.

[0103] For this purpose of personalization, it is possible to offer the user a set of available modification modes and to request a selection by the user of a modification mode to be favored. Optionally, the modification mode thus selected can then be saved as user profile data.

[0104] The proposed modification modes may differ from each other by the nature (shape and / or size and / or color, etc.) of the modification(s) carried out and / or by the value of one or more parameters influencing the amplitude of this or these modifications.

[0105] The amplitude of a modification made can be characterized by an amplitude parameter whose determination in real time depends not only on the target value, but also on the mathematical function making it possible to calculate the amplitude parameter as a function of the difference between the target value and the recorded value of the rotation speed from the physical point of view of the user. In general, the modifications of the visual reference can be controlled as a function of different criteria, alone or combined with each other, these criteria being able to relate for example to perceptual thresholds, to the elapsed time, as well as to the rotation speed of the user's head in relation to the real world and / or to other measured or inferred parameters.

[0106] Parameters influencing the magnitude of a modification made may include parameters of such a mathematical function, such as expected maximum and minimum values ​​for the magnitude parameter, a slope in the particular case of a linear function, etc.

[0107] Furthermore, as already indicated, the target value is calculated based on the movements recorded from the physical point of view and from the virtual point of view, according to a pre-established calculation method. The pre-established calculation method may itself result from a choice among several available calculation methods. Thus, the parameters influencing the amplitude of a modification carried out may relate to the choice of the calculation method for determining the target value and / or to the adjustment of coefficients- ficients involved in this calculation method.

[0108] It is also possible to implement supervised machine learning means to determine the modification mode to be favored among the set of available modification modes.

[0109] Such means may be based, for example, on an analysis of the movements made by the user in response to different tested modes of modification of the visual reference and / or on responses from the user to requests relating, for example, to his comfort during an immersion session in the virtual environment where different types of modifications are successively tested.

Claims

Claims

1. Cyber-discomfort reduction system (12) for navigation in an immersive virtual environment (2), comprising a control unit (7), a virtual visual environment (2), corresponding to a virtual point of view of the user, displayed on a display system (3), a position capture system (6) from the physical point of view of the user (4), and a navigation system (9) moving the virtual point of view of the user in the virtual environment, said system (12) being capable of: monitoring movements from the virtual point of view of the user relative to the virtual environment generated by the navigation system (9); monitoring actual rotations from the physical point of view of the user relative to the real world (11);determining rotation incentives from the user's physical point of view with respect to the real world (11), the rotation incentives relating to at least partial corrections of deviations and / or discrepancies between the movements from the virtual point of view and the actual rotations from the user's physical point of view; and depending on the rotation incentives, modifying in real time a visual reference (10) prepositioned in the virtual visual environment, in which modifying the visual reference comprises modifying the shape of the visual reference.;

2. The system of claim 1, wherein the visual reference (10) is virtually generated and displayed with the virtual environment (2) by the display system (3).

3. The system of claim 1 or 2, wherein modifying the visual reference (10) comprises modifying the orientation and / or appearance of the visual reference.

4. The system of claim 3, wherein the visual reference (10) comprises: a base fixedly positioned relative to the user's physical viewpoint, an end, and a body extending from the base toward the end.

5. The system of claim 4, wherein modifying, in real time, the shape of the visual reference includes, at a minimum, curving the body of the visual reference.

6. The system of claim 4 or 5, wherein modifying, in real time, the orientation of the visual reference comprises, at least, modifying the orientation of the end of the visual reference.

7. System according to one of claims 1 to 6, in which the system is further capable of: performing a comparison between several predefined modification modes of the visual reference by means of a supervised learning model, on the basis of a respective evaluation of the user's follow-up of the rotation recommendations when the visual reference is respectively modified according to each of the predefined modification modes, and choosing, from among the predefined modification modes, a personalized modification mode for the user on the basis of the result of the comparison.

8. System according to one of claims 1 to 7, in which monitoring the actual rotations from the physical point of view of the user relative to the real world comprises collecting, by means of the position capture system (6) from the physical point of view of the user (4), time series indicative of angular parameters relating to the orientation of the user's head, the angular parameters including positions, speeds, accelerations and / or jolts.

9. A method for reducing cyber-discomfort for navigation in an immersive virtual environment (2), the method being implemented by a cyber-discomfort reduction system (12) comprising a control unit (7), a virtual visual environment (2), corresponding to a virtual point of view of the user, displayed on a display system (3), a position capture system (6) from the physical point of view of the user (4), and a navigation system (9) moving the virtual point of view of the user in the virtual environment, said method comprising: monitoring movements from the virtual point of view of the user relative to the virtual environment generated by the navigation system (9); monitoring actual rotations from the physical point of view of the user relative to the real world (11); determining rotation incentives from the physical point of view of the user in relation to the real world (11), the rotation incentives relating to at least partial corrections of deviations and / or discrepancies between the movements from the virtual point of view and the effective rotations from the physical point of view of the user; and depending on the rotation incentives, modifying in real time a visual reference (10) prepositioned in the virtual visual environment, in which modifying the visual reference comprises modifying the shape of the visual reference.

10. Computer program comprising instructions for implementing the method according to claim 9 when this program is executed by a processor.

11. A non-transitory recording medium readable by a computer on which is recorded a program for implementing the method according to claim 9 when this program is executed by a processor.

Images