Method and device for interactive rendering of time-evolving augmented reality scenes - Patents.com

Abstract

An augmented reality scene description is provided that includes relationships between real and virtual objects and interactive triggering and processing of the augmented reality scene. An augmented reality system can read the scene description and execute a corresponding augmented reality application. The scene description includes a scene graph that structures descriptions of real and virtual objects that can be linked to media content items. It also includes behavior metadata items that describe how a user can interact with the scene objects at runtime. Methods and devices are disclosed for managing behaviors including triggers and actions, and for managing ongoing behaviors when a second scene description is received.

Description

[Technical field]

[0001] The present principles generally relate to the field of rendering of augmented reality scene descriptions and augmented reality rendering. This specification is also understood in the context of formatting and playback when augmented reality applications are rendered on end user devices such as mobile devices or head mounted displays (HMDs). [Background technology]

[0002] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present principles that are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present principles. As such, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0003] Augmented Reality (XR) is a technology that enables interactive experiences in which real-world environments and / or video content are augmented by virtual content that may be defined across multiple sensory modalities, including visual, auditory, haptic, etc. During the runtime of an application, virtual content (e.g., 3D content or audio / video files) is rendered in real-time in a manner that is consistent with the user context (environment, viewpoint, device, etc.). Scene graphs (such as those proposed by Khronos / gLTF, and such as the MPEG scene description format or its extensions defined by Apple / USDZ) are a possible way to represent the rendered content. They combine a declarative description of the scene structure linking real-world objects and virtual objects on the one hand, and a binary representation of the virtual content on the other. Although such scene description frameworks ensure that timed media and the corresponding related virtual content are available at all times during the rendering of an application, they do not describe how a user can interact with the scene objects at runtime of an immersive XR experience.

[0004] There are no XR systems that can obtain an extended reality (XR) scene description that contains metadata that describes how a user can interact with scene objects at runtime and how these interactions can be updated during the runtime of the XR application. [Brief description of the drawings]

[0005] The present disclosure will be better understood, and other particular features and advantages will become apparent, on reading the following description, in which reference is made to the accompanying drawings, in which: [Figure 1] FIG. 1 illustrates an exemplary scene graph of an augmented reality scene description in accordance with the present principles. [Figure 2A] FIG. 2A shows syntax for expressing an illustrative example trigger in accordance with the present principles. [Figure 2B]FIG. 2B shows syntax for expressing an illustrative example action in accordance with the present principles. [Figure 2C] FIG. 2C illustrates syntax for expressing an illustrative example behavior in accordance with the present principles. [Figure 2D] FIG. 2D illustrates an exemplary syntax for supplemental information in accordance with the present principles. [Diagram 3] FIG. 3 illustrates an example architecture of an XR processing engine that may be configured to implement the methods described in connection with FIGS. 5 and 6 in accordance with the present principles. [Figure 4] FIG. 4 illustrates an example of one embodiment of the syntax of a data stream for encoding an augmented reality scene description in accordance with the present principles. [Diagram 5] FIG. 5 shows a method for rendering an augmented reality scene, according to a first embodiment of the present principles. [Figure 6] FIG. 6 shows a method for rendering an augmented reality scene according to a second embodiment of the present principles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] The present principles are described more fully below with reference to the accompanying drawings, in which examples of the present principles are shown. However, the present principles may be embodied in many alternative forms and should not be construed as being limited to the embodiments set forth herein. Thus, while the present principles are susceptible to various modifications and alternative forms, specific examples thereof are shown by way of example in the drawings and are described in detail herein. However, it is to be understood that there is no intention to limit the present principles to the particular forms disclosed, but on the contrary, the present disclosure is intended to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present principles as defined by the appended claims.

[0007] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present principles. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that as used herein, the terms "comprises," "comprising," "includes," and / or "including" specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Furthermore, when an element is referred to as "responsive to" or "connected to" another element, it may be directly responsive to or connected to the other element, or intervening elements may be present. In contrast, when an element is referred to as "directly responsive to" or "directly connected to" another element, there are no intervening elements. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items, and may be abbreviated as " / ".

[0008] In this specification, terms such as first, second, etc. may be used to describe various elements, but it is understood that these elements should not be limited by these terms. These terms are used only to distinguish one element from another element. For example, a first element can be called a second element, and similarly, a second element can be called a first element without departing from the teachings of the present principles.

[0009] Some of the figures include arrows on communication paths to indicate a primary direction of communication, however, it should be understood that communication may occur in the opposite direction to that depicted arrow.

[0010] Some examples are described with reference to block diagrams and operational flowcharts, in which each block represents a circuit element, module, or portion of code, including one or more executable instructions for implementing a specified logical function. It should also be noted that in other implementations, the functions noted in the blocks may occur out of the order noted. For example, two blocks shown in succession may in fact be executed substantially simultaneously, or the blocks may be executed in the reverse order, depending on the functionality involved.

[0011] The use of "by one example" or "in one example" herein means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one implementation of the present principles. The appearances of the phrases "by one example" or "in one example" in various places in the specification are not necessarily all referring to the same example, and are not necessarily mutually exclusive of other examples in separate or alternative embodiments.

[0012] Reference signs appearing in the claims are merely illustrative and shall have no limiting effect on the scope of the claims. Although not expressly described, the embodiments and variations may be used in any combination or subcombination.

[0013] FIG. 1 shows an example scene graph 10 of an augmented reality scene description. In this example, the scene graph includes descriptions of real objects 12, e.g., a "flat horizontal surface" (which can be a table or a floor or a plate), and descriptions of virtual objects 13, e.g., an "animation of a walking character". The virtual objects 13 are associated with media content items 14, which are encodings of the data required to render and display the walking character (e.g., as a textured animated 3D mesh). The scene graph 10 also includes nodes 11, which are descriptions of spatial relationships between the real objects described in nodes 12 and the virtual objects described in nodes 13. In this example, nodes 11 describe spatial relationships that would cause a character to walk on a flat surface. When an XR application containing the scene graph 10 is started, the media content items 14 are loaded, rendered, buffered, and displayed when triggered. When a flat surface is detected in the real environment by a sensor (a camera in the example of FIG. 1), the application displays the buffered media content items as described in nodes 11. The timing is managed by the application according to the features detected in the real environment and the timing of animations. A node in the scene graph may also be devoid of description and may only play the role of a parent node to its child nodes.

[0014] XR applications are diverse and may apply to different contexts and real or virtual environments. For example, in an industrial XR application, a virtual 3D content item (e.g., part A of an engine) is displayed when a reference object (part B of the engine) in the real environment is detected by a camera mounted on a head-mounted display device. The 3D content item is placed in the real world at a defined position and scale relative to the detected reference object.

[0015] For example, in an XR application for interior design, a 3D model of a piece of furniture may be displayed when a given image from a catalog is detected in the input camera view. The 3D content is placed in the real world at a position and scale defined relative to the detected reference image. In another application, an audio file may start playing when a user enters an area close to a church (either real or virtually rendered in an augmented reality environment). In another example, an advertising jingle file may be played when a user sees a given can of soda water in the real environment. In an outdoor gaming application, virtual characters may appear depending on the semantics of the scenery observed by the user. For example, a bird character may be suitable for a tree, so if the XR device's sensors detect a real object described by the semantic label "tree", a bird flying around the tree may be added. In a companion application implemented by smart glasses, a car noise may be emitted in the user's headset when a car is detected in the user's camera's field of view to alert the user to a potential danger. Furthermore, the sound may be spatialized to seem to arrive from the direction in which the car was detected.

[0016] XR applications can also augment the real environment with video content instead: the video is displayed on a rendering device, and virtual objects described in the node tree are overlaid when timed events are detected in the video. In such a context, the node tree only contains descriptions of the virtual objects.

[0017] 2A-2D show non-limiting examples of augmented reality scene descriptions according to the present principles.

[0018] In accordance with the present principles, in addition to the node tree described in connection with FIG. 1, behavior metadata items (referred to herein as "behaviors") are added to the scene description. Behaviors are associated with predefined virtual objects and enable run-time interactivity with the predefined virtual objects to a user-specific XR experience. Behaviors are also time-evolving and are updated through a scene description update mechanism. In accordance with the present principles, behaviors are metadata items that may include: One or more triggers, which define one or more conditions that must be met for their activation; - trigger control parameters that define the logical operations between the triggers; - the action to be taken when the trigger is fired according to the trigger control parameters, - action control parameters, which define the order in which actions are executed; - a priority number that allows the selection of the behavior with the highest priority when at least two behaviors on the same virtual object occur simultaneously; - An optional interrupt action to specify how to terminate the action of this behavior that is longer applicable in the scene description update.

[0019] When the second scene description is received, some of the behaviors of the first scene description may be "ongoing", i.e., they have already been triggered and their actions are in progress. The second scene description may be provided as update metadata, which is metadata describing the differences between the first and second scene descriptions. The second scene description includes a node tree describing objects that may be common or different to objects of the first scene description. Objects of the node tree of the first scene description may no longer exist in the second scene description. If objects related to ongoing actions of ongoing behaviors are missing in the second scene description, these ongoing behaviors are no longer applicable. Similarly, if ongoing behaviors are not defined in the second description, the ongoing behaviors are no longer applicable. The interrupt action field describes how exactly to interrupt ongoing actions of ongoing behaviors.

[0020] The format of the node tree is not described here. For example, the MPEG-I scene description framework using the Khronos glTF extension mechanism may be used for the node tree. In this example, the interactivity extension according to the present principles may be applied at the glTF scene level and is called MPEG_scene_interactivity. The corresponding semantics are shown in the following table:

[0021] [Table 1]

[0022] An "M" in the "Used" column means that this field is mandatory in an XR scene description format according to the present principles; an "O" in the "Used" column means that the field is optional.

[0023] 2A-2D, the virtual 3D object is continuously displayed and transformed during the media sequence. When the user's left hand is detected, the virtual 3D object is placed over the user's left hand and continuously follows the user's left hand.

[0024] To support this example interaction scenario, two behaviors are defined: -The first behavior with the following parameters: A single trigger related to a time series of media between 20 and 40 seconds with continuous firing, and Two consecutive actions for activating and transforming a virtual 3D object (node ​​0). -A second behavior with the following parameters: A single trigger associated with the detection of the user's left hand with successive activations, and A single action to place the virtual object (node ​​0) in the user's left hand.

[0025] The items in the array of field "triggers" are defined according to the following table:

[0026] [Table 2]

[0027] For every field in the table, a default value can be determined.

[0028] FIG. 2A shows a syntax compliant with the present principles for expressing the triggers of the illustrative example above. FIG. 2A shows a header indicating that interactivity metadata according to the present principles belongs to a scene description. We explain two triggers required for two behaviors of the illustrative embodiment. The triggers may be listed in the behavior field. Listing them in separate arrays allows the same trigger to be used for several behaviors.

[0029] The items of the array in the field "actions" (shown in Figure 2B) are defined according to the following table:

[0030] [Table 3-1]

[0031] [Table 3-2]

[0032] For every field in the table, a default value can be determined.

[0033] 2B shows a syntax consistent with the present principles for expressing the actions of the illustrative example described above. The field "actions" contains a description of the three actions required to execute the two behaviors of the illustrative example, plus one disable action. The first action to enable the object at node 0 in the node tree has index 0, since it is the first action in the action array. In this example, the action to place the object at node 0 on the user's left hand according to a transformation matrix has index 1, and the action to transform the object at node 0 has index 2. The fourth action to disable the object at node 0 with index 3 is an interrupt action common to the two behaviors.

[0034] The items of the array in the field "behaviors" (shown in Figure 2C) are defined according to the following table:

[0035] [Table 4]

[0036] For every field in the table, a default value can be determined.

[0037] FIG. 2C illustrates a syntax consistent with the present principles for expressing the behaviors of the illustrative example described above. The field "behaviors" contains a description of the two behaviors of the illustrative example. The list of triggers and actions is indicated by indexes in the trigger array of FIG. 2A and the action array of FIG. 2B. The interrupt action of the two behaviors references action number 3 in the action array. The second behavior has a higher priority than the first behavior. Since the two behaviors apply to the same node 0 of the node tree, the second behavior will be selected if the two behaviors are active at the same time.

[0038] FIG. 2D shows an exemplary syntax of supplemental information according to the present principles. For example, scenes and nodes can be named. Triggers, actions and behaviors can also have unique ID numbers or unique names. Therefore, when a scene description is updated, it is easy to detect whether an ongoing behavior or node belongs to the new scene description.

[0039] Figure 3 shows an example architecture of an XR processing engine 30 that can be configured to implement the methods described in relation to Figures 5 and 6. The devices according to the architecture of Figure 3 are linked with other devices via their bus 31 and / or via I / O interfaces 36.

[0040] The device 30 includes the following elements coupled together by a data and address bus 31: a microprocessor 32 (or CPU), for example a DSP (Digital Signal Processor); -ROM (read-only memory) 33, -RAM (random access memory) 34; a storage interface 35; an I / O interface 36 for receiving data to be transmitted from an application; - a power source, e.g. a battery, which is not shown in FIG.

[0041] According to one example, the power source is external to the device. In each of the mentioned memories, the word "register" used herein may correspond to a small volume area (a few bits) or a very large area (e.g., the entire program or a large amount of received or decoded data). The ROM 33 includes at least the programs and parameters. The ROM 33 can store algorithms and instructions for performing the techniques according to the present principles. When switched on, the CPU 32 uploads the program in the RAM and executes the corresponding instructions.

[0042] The RAM 34 contains, in registers, the programs executed by the CPU 32 and uploaded after switching on the device 30, the input data in registers, intermediate data for different states of the methods in registers, and other variables used for the execution of the methods in registers.

[0043] The implementations described herein may be implemented, for example, in a method or process, an apparatus, a computer program product, a data stream, or a signal. Even if discussed only in the context of a single form of implementation (e.g., discussed only as a method or device), the implementation of the discussed features may also be implemented in other forms (e.g., a program). An apparatus may be implemented, for example, in appropriate hardware, software, and firmware. The method may be implemented in a device such as a processor, which generally refers to a processing device, including, for example, a computer, a microprocessor, an integrated circuit, or a programmable logic device. Processors also include communication devices, such as, for example, computers, mobile phones, portable / personal digital assistants ("PDAs"), and other devices that facilitate communication of information between end users.

[0044] The device 30 is linked, for example, via a bus 31 to a set of sensors 37 and a set of rendering devices 38. The sensors 37 may for example be a camera, a microphone, a temperature sensor, an inertial measurement unit, a GPS, a humidity measurement sensor, an IR or UV light sensor, or a wind sensor. The rendering devices 38 may for example be a display, a speaker, a vibrator, heat, a fan, etc.

[0045] According to an embodiment, the device 30 is configured to implement the method described in relation to Figs. 5 and 6, -Mobile devices, -Communication devices, -Gaming devices, - a tablet (or tablet computer), -Laptop, -Still camera, - Equipped with a video camera.

[0046] FIG. 4 shows an example of an embodiment of a syntax for a data stream encoding an augmented reality scene description according to the present principles. FIG. 4 shows an exemplary structure 4 of an XR scene description. The structure consists of containers that organize the stream in independent elements of the syntax. The structure may include a header section 41 that is a set of data common to all syntax elements of the stream. For example, the header section includes some of the metadata about the syntax elements, explaining the nature and role of each of them. The structure also includes a payload that includes a syntax element 42 and a syntax element 43. The syntax element 42 includes data representing the media content item described in the node of the scene graph associated with the virtual element. Images, meshes, and other raw data may be compressed according to a compression method. The syntax element 43 is part of the payload of the data stream and includes data encoding the scene description, as described in relation to FIGS. 2A-2D.

[0047] Fig. 5 shows a method 50 for rendering an augmented reality scene according to embodiment 1 of the present principles. When a first scene description is received, the triggers of the trigger array are considered. One or more of them may be discarded because the rendering device is not equipped to detect their condition. For example, a trigger may be based on temperature if the rendering device does not have a thermal sensor. Thus, the steps of method 50 are applied to at least one trigger and, if possible, to all triggers of the scene description. In step 51, a condition described in the metadata describing the trigger is tested by the rendering device using the associated sensor. If the condition is not met, the activation status set to false is taken as the trigger at run time in step 52. If the condition is met, the rendering device checks in step 53 whether the activation status of the trigger is already set to true. If not, in step 54 the activation status of the trigger is set to true and step 56 is executed. If so, the rendering device checks whether the field activate_once of the trigger in the scene description is set to true. If so, step 56 is skipped. If not, step 56 is executed, which fires the trigger. At step 56, all behaviors that use this trigger are notified that the trigger has been fired or re-fired.

[0048] At runtime, every behavior has an in progress status that indicates whether the behavior's trigger has been activated according to its activation mode, and therefore whether the behavior's action has actually been performed.

[0049] FIG. 6 shows a method 60 for rendering an augmented reality scene according to embodiment 2 of the present principles. In method 60, an augmented reality application is already running. A first scene description with interactivity extensions according to the present principles has already been received and is used to run the XR application. At least one behavior is ongoing, i.e. its action is executed. In step 61, a second scene description is obtained. If the second scene extension does not have interactivity extensions, the second scene extension is considered to have an empty array of behaviors. The obtained data may be a partial description indicating differences between the first scene description and the second scene description. The second description may include new behaviors that were not included in the first description or behaviors equivalent to behaviors included in the first scene description. Method 60 is applied to all ongoing behaviors of the first scene description. In step 62, the rendering device checks whether a given ongoing behavior of the first scene description is applicable to an object of the node tree of the second scene description. In effect, the actions of the ongoing behavior of the first scene description are applied to the objects described in the node tree of the first scene description. If the node tree of the second description does not contain these objects, or if these objects are modified in the second scene description and the actions of the ongoing behavior are not applied to these modified objects, the ongoing behavior is no longer applicable. Then, in steps 63 and 64, the ongoing behavior is interrupted and stopped. If the ongoing behavior is still applicable in the context of the second scene description, the ongoing behavior continues and step 65 is executed. In a variant, if the second scene description does not contain a behavior equivalent to the ongoing behavior, the ongoing behavior is considered to be no longer applicable.

[0050] In step 63, the interrupt action is executed (if there is an interrupt action in the description). In step 64, any ongoing behavior is stopped. Then step 65 is executed. In step 65, the second scene description replaces the first description in the running XR application. Method 60 is repeated if a new scene description is received.

[0051] The implementations described herein may be implemented, for example, in a method or process, an apparatus, a computer program product, a data stream, or a signal. Even if discussed only in the context of a single form of implementation (e.g., discussed only as a method or device), the implementation of the discussed features may also be implemented in other forms (e.g., a program). An apparatus may be implemented, for example, in appropriate hardware, software, and firmware. The method may be implemented in a device such as a processor, which generally refers to a processing device, including, for example, a computer, a microprocessor, an integrated circuit, or a programmable logic device. Processors also include communication devices, such as, for example, smartphones, tablets, computers, mobile phones, handheld / personal digital assistants ("PDAs"), and other devices that facilitate communication of information between end users.

[0052] Implementations of the various processes and features described herein may be embodied in a variety of different equipment or applications, particularly equipment or applications associated with, for example, data encoding, data decoding, view generation, texture processing, and other processing of images and associated texture and / or depth information. Examples of such equipment include encoders, decoders, post-processors that process output from decoders, pre-processors that provide input to encoders, video coders, video decoders, video codecs, web servers, set-top boxes, laptops, personal computers, mobile phones, PDAs, and other communication devices. As should be clear, the equipment may be mobile and installed in a mobile vehicle.

[0053] In addition, the method may be implemented by instructions executed by a processor, and such instructions (and / or data values ​​produced by the implementation) may be stored on a processor-readable medium, such as, for example, an integrated circuit, a software carrier, or other storage device, such as, for example, a hard disk, a compact diskette ("CD"), an optical disk (such as, for example, a DVD, often referred to as a digital versatile disk or digital video disk), a random access memory ("RAM"), or a read-only memory ("ROM"). The instructions may form an application program tangibly embodied on the processor-readable medium. The instructions may be, for example, hardware, firmware, software, or a combination. The instructions may be found, for example, in an operating system, a separate application, or a combination of the two. Thus, a processor may be characterized as both, for example, a device configured to execute a process and a device that includes a processor-readable medium (such as a storage device) having instructions for executing a process. Furthermore, the processor-readable medium may store data values ​​produced by the implementation in addition to or in place of instructions.

[0054] As will be apparent to one of ordinary skill in the art, implementations may result in a variety of signals formatted to carry information that may be, for example, stored or transmitted. Information may include, for example, instructions for performing a method or data generated by one of the described implementations. For example, a signal may be formatted to carry as data rules for writing or reading syntax of the described embodiments, or to carry as data the actual syntax values ​​written by the described embodiments. Such a signal may be formatted, for example, as an electromagnetic wave (e.g., using the radio frequency portion of the spectrum) or as a baseband signal. Formatting may include, for example, encoding a data stream and modulating a carrier wave with the encoded data stream. The information that the signal carries may be, for example, analog information or digital information. The signal may be transmitted by a variety of different wired or wireless links, as is known. The signal may be stored in a processor-readable medium.

[0055] A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made. For example, elements of different implementations can be combined, supplemented, modified, or deleted to produce other implementations. In addition, those skilled in the art will understand that other structures and processes can be substituted for those disclosed, and the resulting implementations perform at least substantially the same functions in at least substantially the same manner to achieve at least substantially the same results as the disclosed implementations. Thus, these and other implementations are contemplated by the present application.

Claims

1. 1. A method for rendering an augmented reality scene to a user in a timed environment, comprising: - obtaining a description of the augmented reality scene, said description comprising: a scene tree linking nodes describing at least one of timed objects, virtual objects, or relationships between objects; A plurality of behavior data items, where one behavior data item is at least one trigger, where a trigger is a description of a condition; at least one trigger that is activated when a condition is detected in the timed environment; - obtaining a description of the augmented reality scene, the description comprising a plurality of behavior data items including at least one action, the one action being a description of a process to be executed by an augmented reality engine on an object described by a node of the scene tree; - applying an action of a behavior data item conditional on said at least one trigger of said behavior data item being activated; A method comprising:

2. - if said description of the augmented reality scene is obtained, attributing to at least one trigger of said description a activation status set to false; - setting the activation status of the at least one trigger to true and activating the trigger the first time the condition of the at least one trigger is satisfied.

3. 3. The method of claim 2, further comprising: when the condition of the at least one trigger is satisfied, if the activation status of the trigger is set to true, then the trigger is activated only if the description of the trigger allows a second activation.

4. The method according to any one of claims 1 to 3, wherein a behavior data item includes a priority parameter, and when the at least one trigger of the at least two behavior data items is activated, the at least one action of one of the at least two behavior data items is applied according to the priority parameter of the at least two behavior data items.

5. 1. A method for updating at run-time a first description of an augmented reality scene including behavior data items with a second description of the augmented reality scene, the method comprising: for each ongoing behavior data item of the first description, if the ongoing behavior data item is not applicable to the second description, the method comprising: - processing an interrupt action, if one exists, for said ongoing behavior data item in said first description; - stopping said ongoing behavior data item; applying said second description.

6. 1. A device for rendering an augmented reality scene to a user in a timed environment, said device comprising: - obtaining a description of the augmented reality scene, said description comprising: a scene tree linking nodes describing at least one of timed objects, virtual objects, or relationships between objects; A plurality of behavior data items, where one behavior data item is at least one trigger, where a trigger is a description of a condition; at least one trigger that is activated when a condition is detected in the timed environment; - obtaining a description of the augmented reality scene, the description comprising a plurality of behavior data items including at least one action, the one action being a description of a process to be executed by an augmented reality engine on an object described by a node of the scene tree; - applying an action of a behavior data item conditional on said at least one trigger of said behavior data item being activated; A device comprising a processor and associated memory configured to perform the steps of:

7. The processor, - if said description of the augmented reality scene is obtained, attributing to at least one trigger of said description an activation status set to false; - setting the activation status of said at least one trigger to true and activating said trigger the first time said condition of said at least one trigger is satisfied; The device of claim 6 , further configured to:

8. 8. The device of claim 7, wherein the processor is further configured to, when the condition of the at least one trigger is satisfied, if the activation status of the trigger is set to true, activate the trigger only if the description of the trigger allows a second activation.

9. A device according to any one of claims 6 to 8, wherein a behavior data item includes a priority parameter, and the processor is configured to apply the at least one action of one of the at least two behavior data items in accordance with the priority parameter of the at least two behavior data items when the at least one trigger of the at least two behavior data items is activated.

10. 1. A device for updating at run-time a first description of an augmented reality scene comprising behavior data items with a second description of the augmented reality scene, the device comprising: for each ongoing behavior data item of the first description, if the ongoing behavior data item is not applicable to the second description, - processing an interrupt action, if one exists, for an ongoing behavior data item in said first description; - stopping said ongoing behavior data item; and applying the second description.

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