Hierarchical single-axis rotation constraint system and method in motion capture data processing

Abstract

The application discloses a hierarchical single-axis rotation constraint system and method in motion capture data processing, comprising a data import processing module, which is used for converting IK of a role into FK when importing motion capture data, and adjusting initial actions of a waist and legs of the role to be consistent with initial states of the motion capture data; a skeleton replication module, which is used for replicating a driving skeleton in the motion capture data to generate an intermediate skeleton chain, and replicating the intermediate skeleton chain as an IK skeleton; and an intermediate IK skeleton system creation module, which is used for creating an intermediate IK skeleton system based on the IK skeleton, and realizing single-axis rotation constraint on the intermediate IK skeleton system according to a three-level constraint architecture. The application has the advantages of automatically processing role binding, matching skeleton driving and motion capture data, avoiding joint abnormalities caused by multi-axis superimposed rotation, reserving details and characteristics of the motion capture data, eliminating degree of freedom conflicts, and improving animation production quality and efficiency.

Description

Technical Field

[0001] This invention belongs to the field of animation production and game development technology, specifically relating to a hierarchical single-axis rotation constraint system and method in motion capture data processing. Background Technology

[0002] With the ever-increasing demands of animation production and game development, efficient and accurate processing of character rigging and motion capture data has become a key technological bottleneck. Traditional character rigging methods typically require manual adjustment of the relationship between bones and controllers, as well as complex matching and constraint operations on motion capture data. This approach is not only time-consuming and error-prone, but also inefficient, especially when dealing with complex characters or special skeletal structures. More importantly, existing technologies lack a systematic automated solution for the initial alignment and driving process between motion capture data and the rigged character, failing to meet the demands of efficient animation production. The typical processing workflow for motion capture data in Maya currently suffers from the following technical pain points: directly using motion capture data to drive the HumanIK controller can easily result in unnatural spiral rotations (multi-axis superimposed rotations) at the elbow / knee joints; conventional IK processing loses detailed features of the motion capture data, making precise control of Maya's native skeleton impossible; direct constraints can lead to conflicts in degrees of freedom, manifesting as joint tremors or abnormal bending. These problems severely restrict the quality and efficiency of animation output, necessitating a technological solution that automates the entire process from data integration to bone-driven control. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of the aforementioned background technology by providing a hierarchical single-axis rotation constraint system and method for motion capture data processing. This system has the advantages of automatically processing character binding, bone driving, and motion capture data matching, thereby avoiding joint abnormalities caused by multi-axis superimposed rotation, fully preserving the detailed features of motion capture data, effectively eliminating degree-of-freedom conflicts, and ultimately improving the quality and efficiency of animation production.

[0004] The technical solution adopted in this invention is: a hierarchical single-axis rotation constraint system for motion capture data processing, comprising... The data import and processing module is used to convert the character's IK to FK when importing motion capture data, and to adjust the initial movements of the character's waist and legs to be consistent with the initial state of the motion capture data. The skeleton replication module is used to replicate the driving skeletons in the motion capture data to generate an intermediate skeleton chain, and create the corresponding IK skeleton based on the intermediate skeleton chain; The intermediate IK skeleton system creation module is used to create an intermediate IK skeleton system based on the IK skeleton, and to constrain the intermediate IK skeleton system according to the three-level constraint architecture to achieve single-axis rotation constraint.

[0005] Furthermore, the intermediate skeletal chain includes an initial joint, intermediate joints, and an end joint.

[0006] Furthermore, the IK skeleton includes an IK initiation joint, an IK intermediate joint, and an IK distal joint.

[0007] Furthermore, the process of creating the intermediate IK skeleton system is as follows: Select the IK start joint of the IK skeleton as the starting point, and construct the IK control handle together with the IK end joint of the IK skeleton. Use the IK end joint to apply point constraints to the IK control handle, and use the IK end joint to apply directional constraints to the end joints of the intermediate bone chain. Create a polar vector locator, constrain the polar vector locator to the middle joint of the IK skeleton, complete the coordinate system zeroing and preset offset processing of the polar vector locator, use the processed polar vector locator to apply polar vector constraints to the IK handle, and constrain the processed polar vector locator to the middle skeleton chain. Establish the parent-child constraint relationship between the IK starting joint and the processed polar vector positioner.

[0008] Furthermore, the three-level constraint architecture is as follows: Level 1 constraint: motion capture skeleton drives intermediate skeleton chain; Second-level constraint: Construct IK chains separately for key parts, create locators at the intermediate nodes of the IK chains, set the local coordinate system of the locators to zero, and use the processed locators as the polar vector constraint objects of the IK control handles. Level 3 constraint: IK end joint orientation constraint final controller.

[0009] Furthermore, it also includes a finger baking judgment module, which is used to identify the number of finger bones in the motion capture data. If the number of finger bones is greater than a set threshold, the finger bones are baked; otherwise, the finger baking process is skipped.

[0010] Furthermore, it also includes a function option module, which provides a programmable configuration interface for specific functions.

[0011] Furthermore, the specific functions include any one or more of chest IK fusion, motion capture data displacement matching, and wrist IK fusion.

[0012] Furthermore, it also includes a node removal module, which is used to automatically identify and clean up unknown nodes after applying motion capture data.

[0013] A hierarchical single-axis rotation constraint method for motion capture data processing includes the following steps: When importing motion capture data, convert the character's IK to FK and adjust the initial movements of the character's waist and legs to match the initial state of the motion capture data. The driving skeleton in the motion capture data is copied to generate an intermediate skeleton chain, and the corresponding IK skeleton is created based on the intermediate skeleton chain; An intermediate IK skeleton system is created based on the IK skeleton, and a single-axis rotation constraint is achieved by constraining the intermediate IK skeleton system according to the three-level constraint architecture.

[0014] The beneficial effects of this invention are as follows: This invention achieves initial pose alignment through a data import and processing module, constructs a precisely matched skeletal structure through a bone replication module, and restricts multi-axis rotation to single-axis rotation through an intermediate IK skeleton system creation module combined with a three-level constraint architecture. This effectively solves the problems of abnormal joint rotation, loss of detail, and degree-of-freedom conflict caused by traditional methods. It has the advantages of automating character binding, matching bone drive with motion capture data, avoiding joint abnormalities caused by multi-axis superimposed rotation, preserving the detailed features of motion capture data, eliminating degree-of-freedom conflict, and improving the quality and efficiency of animation production. Attached Figure Description

[0015] Figure 1 This is a system schematic diagram of the present invention.

[0016] Figure 2 This is a constraint diagram of the present invention.

[0017] Figure 3 This is a flowchart of the method of the present invention. Detailed Implementation

[0018] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0019] In current technologies, the requirements for the naturalness and precision of character movements are increasingly demanding in animation production and game development. Traditional character rigging methods rely on manually adjusting the relationship between bones and controllers, requiring complex matching and constraint operations when processing motion capture data. This method is inefficient and error-prone, especially when dealing with complex skeletal structures, making it difficult to guarantee smooth movements. When existing technologies directly use motion capture data to drive controllers, unnatural spiral rotation often occurs in elbow and knee joints. Conventional inverse kinematics processing loses motion details, while direct constraint methods are prone to causing degree-of-freedom conflicts, leading to joint vibration or abnormal bending.

[0020] To address the aforementioned issues, a mechanism is needed to automatically decouple motion capture data from skeletal control. First, initial pose deviations must be eliminated, establishing a consistency benchmark between the skeletal structure and motion capture data. Next, the driving and constraint logics are separated through skeletal replication, preventing direct coupling between the original data and the control system. Finally, a hierarchical constraint architecture needs to be designed to transform multi-axis rotation into single-axis control while preserving detailed motion features. This approach uses an intermediate skeletal chain as a data buffer layer, combined with the coordinate system zeroing operation of the polar vector locator, to form a progressively increasing degree-of-freedom constraint mechanism.

[0021] Therefore, this invention proposes a hierarchical single-axis rotation constraint system for motion capture data processing, such as... Figure 1 As shown, the system includes a data import and processing module, used to convert the inverse kinematics (IK) of the character into forward kinematics (FK) when importing motion capture data, and to adjust the initial movements of the character's waist and legs to match the initial state of the motion capture data; a skeleton replication module, used to replicate the driving bones in the motion capture data to generate an intermediate skeleton chain, and to create corresponding IK skeletons based on the intermediate skeleton chain; and an intermediate IK skeleton system creation module, used to create an intermediate IK skeleton system based on the IK skeletons, and to constrain the intermediate IK skeleton system according to a three-level constraint architecture to achieve single-axis rotational constraints, the constraint process being as follows. Figure 2 As shown.

[0022] The data import and processing module is a functional unit that converts the character control mode from target-driven to skeleton-driven. This can be achieved using a skeleton coordinate system reset algorithm to eliminate initial posture differences. The skeleton replication module generates intermediate transitional skeleton structures, which can be implemented using a depth replication algorithm to isolate the original motion capture data from the control system. The intermediate IK skeleton system creation module is a functional component that constructs hierarchical constraint relationships. This can be achieved using a combination of polar vector locators and orientation constraints to convert multi-degree-of-freedom rotation into single-axis control.

[0023] Specifically, the data import and processing module establishes the initial alignment between the character skeleton and the motion capture data through coordinate system transformation, providing a reference coordinate system for subsequent constraints. The skeleton replication module generates an intermediate skeleton chain that retains the characteristics of the original motion capture data, while simultaneously creating an independent inverse kinematics skeleton chain as a control carrier. The intermediate inverse kinematics skeleton system creation module progressively restricts rotational degrees of freedom through a three-level constraint architecture: the first level of constraint establishes the driving relationship between the motion capture skeleton and the intermediate skeleton; the second level of constraint eliminates multi-axis rotational components through the coordinate system zeroing operation of the polar vector positioner; and the third level of constraint ensures motion stability through end-joint orientation control. The constraint processing of the polar vector positioner at the intermediate joints can decompose rotational motion into a single axial component while preserving the subtle features of the original motion.

[0024] Through the above technical solution, this invention effectively eliminates the multi-axis superimposed rotation phenomenon in the motion capture data-driven process, avoiding abnormal joint bending. By cooperating with the intermediate skeletal chain and the three-level constraint architecture, precise matching between motion capture data and the character's skeleton is achieved, resolving the degree-of-freedom conflict problem while maintaining the integrity of motion details. The intermediate joint constraint mechanism of the polar vector locator transforms complex rotational motion into single-axis control, significantly improving the naturalness and smoothness of the character's movements.

[0025] The present invention further proposes an intermediate skeletal chain comprising an initial joint, intermediate joints, and an end joint.

[0026] In this context, the starting joint refers to the driving start point of the skeletal chain, which can be generated by copying the root node of the corresponding bone in the motion capture data, and is used to establish the initial binding relationship with the motion capture bone. The intermediate joint refers to the transfer node located in the middle of the skeletal chain, which can be generated by copying the original bone hierarchy structure, and is used to decompose multi-axis rotational degrees of freedom. The end joint refers to the final output node of the skeletal chain, which can be generated by copying the end bone, and is used to establish directional constraint relationships with the target bone.

[0027] Specifically, the initial joint rotates synchronously with the drive source of the motion-captured skeleton to ensure initial posture matching accuracy. Intermediate joints decompose the complex rotations of the original motion-captured data into single-axis progressive motions through a hierarchical structure, with each intermediate joint retaining only a single rotational degree of freedom. The end joints transmit the processed single-axis rotations to the target skeleton through directional constraints, maintaining rotational axis consistency within the constraint space. This three-level joint partitioning, through a physical hierarchical isolation mechanism, transforms complex motions that might otherwise result in multi-axis superimposed rotations into single-axis sequential transmission, eliminating degree-of-freedom conflicts while preserving the original motion characteristics.

[0028] Through the above technical solution, this invention solves the problem of motion transmission deviation caused by the lack of joint hierarchy. By controlling the rotation of three joints in stages, it ensures that the rotational transmission path from motion capture data to the target skeleton maintains uniaxial characteristics. The starting joint performs initial posture calibration, the intermediate joints complete multiaxial rotational decomposition, and the end joint ensures the final output accuracy, forming a complete uniaxial rotational constraint system.

[0029] The present invention further proposes that the IK skeleton includes the IK initiation joint, the IK intermediate joint, and the IK distal joint.

[0030] In this context, the IK initiating joint refers to the driving starting point of the skeletal chain, which can be implemented using the starting position coordinates of the skeletal chain in the motion capture data. It defines the initial spatial position and rotational reference of the skeletal chain. The IK intermediate joint refers to the bending control node of the skeletal chain, which can be implemented using joint coordinates constrained by a polar vector locator. The polar vector constraint restricts the rotational degree of freedom to a single axis. The IK end joint refers to the end execution node of the skeletal chain, which can be implemented using end coordinates constrained by direction. It is used to accurately transfer motion data to the target skeletal chain.

[0031] Specifically, by dividing the IK skeleton into a three-segment hierarchical structure, the starting joint establishes the spatial reference of the skeleton chain, the intermediate joints receive axial constraints from the polar vector locator to eliminate multi-axis rotational degrees of freedom, and the end joints transmit motion data to the intermediate skeleton chain through directional constraints. At the intermediate joints, after the polar vector locator is zeroed out in the coordinate system, the possible X / Y / Z three-axis rotation is simplified to a single-axis rotation, thereby eliminating the helical rotation phenomenon of the elbow and knee joints. When establishing directional constraints between the end joints and the end joints of the intermediate skeleton chain, the hierarchical transmission relationship of the skeleton chain ensures that the rotational details of the motion capture data can be completely preserved and accurately mapped to the target skeleton.

[0032] Through the above technical solution, the present invention effectively eliminates the unnatural spiral rotation phenomenon of the elbow and knee joints when driven by motion capture data. At the same time, through the hierarchical constraint mechanism, the rotational details of the motion capture data are completely preserved, so that the bone control accuracy reaches the same rotation angle and axial offset as the original motion capture data.

[0033] This invention further proposes a process for creating an intermediate IK skeleton system, including a combination of techniques such as constructing IK handles and applying point and orientation constraints, creating polar vector locators and implementing polar vector constraints, and establishing parent-child constraint relationships. The specific process is as follows: Select the IK start joint of the IK skeleton as the starting point, and construct the IK control handle together with the IK end joint of the IK skeleton. Use the IK end joint to apply point constraints to the IK control handle, and use the IK end joint to apply directional constraints to the end joints of the intermediate bone chain. Create a polar vector locator, constrain the polar vector locator to the middle joint of the IK skeleton, complete the coordinate system zeroing and preset offset processing of the polar vector locator, use the processed polar vector locator to apply polar vector constraints to the IK handle, and constrain the processed polar vector locator to the middle skeleton chain. Establish the parent-child constraint relationship between the IK starting joint and the processed polar vector positioner.

[0034] In this context, the IK handle refers to the inverse kinematics control structure built from the starting and ending joints, specifically implemented using the IKHandle tool in Maya software, used to establish the end-position control mechanism of the skeletal chain. The polar vector locator is a virtual controller used to constrain the rotation direction of joints, specifically implemented using a locator object in conjunction with constraint nodes, eliminating multi-axis rotation interference through coordinate system zeroing. Coordinate system zeroing refers to the operation of aligning the locator's local coordinate system with the global coordinate system, specifically implemented using the freeze transform command, used to eliminate the initial offset of the skeletal structure. Preset offset processing refers to the configuration operation of adjusting the locator position according to the bone length, specifically implemented using numerical offset parameter settings, used to adapt to the skeletal structure of characters with different body types. Parent-child constraint relationships establish hierarchical control links between objects, specifically implemented using the parentConstraint node, used to form a closed-loop control system.

[0035] Specifically, during the IK control handle construction phase, the end effector joints apply point constraints to the control handle to synchronize the end effector position with the motion capture data, while directional constraints on the end effector joints of the intermediate skeletal chain restrict their rotational degrees of freedom. After the polar vector positioner is constrained to the intermediate joints, the rotational axis superposition error is eliminated by zeroing the coordinate system, and a preset offset ensures spatial matching between the positioner and the skeletal structure. The processed positioner applies polar vector constraints to the control handle, simplifying 3D rotation into planar single-axis rotation. Simultaneously, the constraint relationship between the positioner and the intermediate skeletal chain forms dual control. The establishment of parent-child constraint relationships enables the initial joint and the positioner to form a motion association, further solidifying the constraint effect of single-axis rotation. The synergistic effect of each constraint level, through the combination of mathematical zeroing and physical constraints, effectively eliminates the degree-of-freedom conflicts caused by multi-axis rotation.

[0036] This invention restricts rotational degrees of freedom to a single plane through a dual constraint structure of an intermediate skeletal chain and a polar vector locator. Furthermore, it achieves precise matching of the skeletal structure through a combination of locator zeroing operation and preset offset processing. A stable hierarchical control system is formed by establishing parent-child constraint relationships.

[0037] Through the above technical solutions, this invention achieves effective control of the rotational degrees of freedom of motion-captured skeletons, restricting the originally possible three-dimensional multi-axis rotation to a single-axis movement, eliminating abnormal joint bending and shaking. The zeroing process of the locator coordinate system solves the problem of overlapping rotational axes caused by initial skeleton posture deviations, and the preset offset configuration ensures adaptability to characters of different body types. The construction of the closed-loop constraint system avoids joint shaking caused by degree-of-freedom conflicts in traditional methods, keeping the motion trajectory of the animated character smooth and stable.

[0038] This invention further proposes a three-level constraint architecture. The first level constraint establishes an initial association through motion capture skeleton driving the intermediate skeleton chain. The second level constraint constructs an IK chain separately at key parts, creates a locator at the intermediate node of the IK chain, sets the local coordinate system of the locator to zero, and uses the processed locator as the polar vector constraint object of the IK control handle. The third level constraint constrains the final controller through IK end joint orientation constraint.

[0039] The intermediate skeleton chain refers to the transitional skeleton structure generated by copying the motion-captured skeleton. Specifically, it can be implemented using a chain structure of starting joints, intermediate joints, and end joints. This establishes an indirect driving relationship between the motion-captured data and the target skeleton, avoiding freedom conflicts caused by direct constraints. The motion-captured skeleton (the skeleton directly bound to the character's body) acts as the driving source, driving the intermediate skeleton chain (an artificially constructed auxiliary skeleton chain) through the IK (Inverse Kinematics) algorithm, ensuring that the initial positions / poses of the intermediate skeleton's starting, intermediate, and end joints perfectly match the motion-captured data. The locator is an auxiliary object used to control the rotational degrees of freedom of the IK chain. Specifically, it can be implemented using virtual coordinate points with local coordinate systems zeroed out, ensuring the accuracy of rotational constraints by eliminating coordinate system offset interference. Polar vector constraints are the operation method that restricts the rotation axis of the IK handle. Specifically, it can be implemented by establishing a polar vector association between the locator and the IK handle, simplifying multi-axis rotation into single-axis rotation, thereby avoiding abnormal joint bending. Separate IK chains are constructed for key parts such as the elbow and knee (e.g., the elbow IK chain includes the upper arm and forearm bones) to avoid coupling interference with other skeleton chains. By using the polar vector constraint of the locator (allowing rotation only around a single axis), potentially multi-axis rotations (such as simultaneous bending of the elbow around the X-axis and twisting around the Y-axis) are restricted to single-axis rotations (such as bending only around the X-axis), reducing the complexity of animation production and avoiding motion distortion caused by multi-axis coupling. Orientation constraints refer to the constraint method controlling the rotation direction of the end-joint. This can be achieved by passing the rotation parameters of the IK end-joint to the final controller, ensuring accurate reproduction of motion details. The function of the constraint final controller is to lock the direction and angle of the final motion, ensuring that the movement of the end-joint (such as the wrist or ankle) conforms to the expectations of the motion capture data and avoiding deviations caused by multi-axis rotation.

[0040] Specifically, the motion capture skeleton first drives the intermediate skeleton chain to synchronize the initial posture and establish basic motion trajectory matching. After constructing independent IK chains at key locations, the coordinate system zeroing operation of the intermediate node locator eliminates rotational interference sources. Then, polar vector constraints restrict the rotational degree of freedom of the IK control handle to a single axis. Finally, the IK end joint applies directional constraints to the controller, transmitting the rotational parameters constrained by the single axis to the target skeleton, forming a complete constraint system from basic posture matching to precise end-effector control.

[0041] Through the above technical solutions, the present invention can eliminate the phenomenon of multi-axis rotation superposition of joints during motion capture data driving, and avoid joint shaking or abnormal bending; through the layered processing of intermediate skeletal chains and polar vector constraints, the detailed features of motion capture data are preserved while restricting degrees of freedom; and through end-effector orientation constraints, the target skeleton is precisely controlled, ensuring the consistency of motion stability and data reproduction.

[0042] The present invention further proposes a finger baking judgment module to identify the number of finger bones in motion capture data. If the number of finger bones is greater than a set threshold, the finger bones are baked; otherwise, the finger baking step is skipped.

[0043] The finger baking judgment module is a logical unit that controls the processing flow by detecting the number of skeletal nodes. Specifically, it can be implemented using a skeletal node traversal algorithm combined with conditional statements to dynamically identify the complexity of the finger skeletal structure. The threshold setting refers to a pre-defined critical number of bones that triggers the baking process. This can be implemented using configuration file parameters or a dynamic calculation algorithm to balance data processing accuracy and computational efficiency. The baking process involves converting skeletal animation data into a keyframe sequence. This can be implemented using a keyframe interpolation algorithm combined with bone weight calculation to preserve the detailed features of complex finger movements.

[0044] Specifically, when motion capture data is imported into the system, the finger baking judgment module counts the number of finger joint nodes by traversing the skeletal hierarchy. When the number of finger bones exceeds a set threshold, the baking process is automatically triggered, converting continuous motion data into a discrete keyframe sequence using a keyframe interpolation algorithm. When the number of finger bones does not reach the threshold, the process jumps directly to the subsequent processing stage. This judgment mechanism uses conditional branch control to perform resource-intensive computations only when the complexity of the skeletal structure reaches a preset standard, thereby avoiding unnecessary baking operations on simple skeletal structures.

[0045] This invention establishes a correlation mechanism between the number of bones and the processing flow, enabling dynamic allocation of processing resources and effectively eliminating redundant computations in low-complexity scenarios. Through this technical solution, the invention can automatically select the processing path based on the actual complexity of the finger bones, significantly reducing computation time for simple bone structures while ensuring the integrity of complex finger movement data, thus improving the overall efficiency of motion capture data processing.

[0046] The present invention further proposes a function option module for providing a programmable configuration interface for specific functions.

[0047] The function option module refers to a system component with functional expansion capabilities. It can be implemented using a plug-in architecture, with dynamic loading of function modules through an interface layer. This module decouples the core system from the functional implementation through abstract interface design, enabling system scalability. The programmable configuration interface is an interactive channel that supports external programming control. It can be implemented using an application programming interface (API) or a scripting interface, allowing users to configure function parameters through programming instructions. This interface defines function call methods through standardized protocols, enabling plug-and-play functionality for the function modules.

[0048] Specifically, the function option module receives external commands through a programmable configuration interface and invokes the corresponding functional processing logic based on the command type. For example, when chest IK fusion is required, the interface parses the programming command and activates the corresponding skeletal fusion algorithm module. In motion capture data displacement matching scenarios, the interface interacts with the displacement compensation algorithm through the coordinate transformation module to complete the data alignment operation. This module adopts a layered architecture design, with the interface layer responsible for command parsing and resource scheduling, and the function layer executing specific business logic, ensuring that functional expansion does not affect the operational stability of the core constraint architecture.

[0049] This invention establishes a function extension mechanism through a programmable configuration interface, enabling users to independently select and enable specific function combinations such as chest IK fusion and wrist IK fusion based on the character's skeletal structure characteristics or animation production needs, without modifying the underlying system architecture.

[0050] Through the above technical solution, this invention achieves dynamic configuration capability for motion capture data processing, allowing users to flexibly select and enable specific functional modules according to actual project needs, thus solving the problem of insufficient adaptability caused by the fixed functions of traditional systems. This solution ensures seamless integration of newly added functional modules with the original constraint architecture through interface layer instruction parsing and resource scheduling mechanisms, improving functional expansion efficiency while maintaining system stability.

[0051] This invention further proposes a flexible expansion and customization process for any one or more functions among chest IK fusion, motion capture data displacement matching, and wrist IK fusion through a programmable configuration interface.

[0052] Chest IK fusion refers to kinematic matching of the chest skeleton with the driving data using inverse kinematics algorithms. Specifically, it can be achieved using inverse skeletal chain calculation methods to eliminate joint angle deviations caused by trunk movements. Motion capture data displacement matching involves establishing a spatial correspondence between the overall character displacement and the motion capture data using spatial coordinate transformation algorithms. This can be achieved using rigid body transformation matrix calculation methods to address differences in the spatial coordinate systems between the character's root node and the motion capture data source. Wrist IK fusion involves inverse kinematic optimization of the motion trajectory of the hand's end effectors. This can be achieved using end effector path interpolation algorithms to maintain the natural bending shape of the hand joints during complex movements.

[0053] Specifically, the programmable configuration interface encapsulates the three types of functions into independent functional units through a parameterized configuration module. When processing chest movements, the inverse kinematics algorithm automatically calculates the rotation angle of the thoracic vertebrae, ensuring biomechanical consistency between chest cavity movements and shoulder actions. When processing overall character displacement, the coordinate transformation module calculates the spatial offset between the character's root node and the motion capture data source in real time, eliminating coordinate system differences through rigid body transformation. For hand movements, the end effector path interpolation algorithm continuously optimizes the wrist joint's rotation trajectory, preventing unnatural distortion of the hand bones. These three types of functions can be activated individually to process specific parts or combined to form a composite processing mode, with the computational priority and influence weight of each function dynamically adjusted through interface parameters.

[0054] This invention enables the dynamic combination of functional modules through a programmable interface, allowing the system to automatically adapt to the processing requirements of different skeletal structures. Through this technical solution, the invention achieves precise control of the motion characteristics of key parts during motion capture data processing. While maintaining the stability of the core constraint mechanism, it can automatically select the optimal processing mode for different character skeletal features. When processing biological characters, the chest and wrist fusion function can be activated simultaneously; when processing mechanical characters, the focus is on displacement matching accuracy. This solution effectively solves the technical bottleneck of traditional technologies that require repeated modification of constraint relationships when processing irregular skeletons or complex movements, and avoids the degree-of-freedom conflict problem caused by multi-part coordinated movement.

[0055] This invention further proposes a node removal module for automatically identifying and cleaning up unknown nodes after applying motion capture data.

[0056] The node removal module is a program unit that performs automated node detection and removal. Specifically, it uses a node traversal algorithm combined with a pre-defined rule base to identify non-standard nodes in the skeletal hierarchy by matching them with abnormal feature patterns. This module eliminates redundant nodes from interfering with the skeletal system through an active screening mechanism. Unknown nodes refer to unexpected intermediate nodes generated during motion capture data conversion, including improperly released temporary control nodes or residual invalid constraint nodes. These can be identified by detecting non-standard naming rules or abnormal constraint relationships in node attributes. This feature maintains the purity of the skeletal system by eliminating unnecessary nodes.

[0057] Specifically, after the motion capture data completes the mapping of the driving skeleton, the node removal module initiates a scanning program to traverse all associated nodes. By comparing the preset standard skeleton naming rules with the node attribute parameters, temporary nodes not defined in the original binding architecture are filtered out. For detected unknown nodes, a hierarchical deletion strategy is adopted to first remove their constraints before performing physical deletion. This process is automatically triggered after each frame of data processing to ensure that interference factors that may cause conflicts in degrees of freedom are eliminated before subsequent constraint calculations.

[0058] In some implementations, the node removal module can be configured to selectively retain debug nodes with specific tags, such as temporary nodes marked "debug" during the development phase. The cleanup operation can be set to perform a depth-first traversal of the skeletal hierarchy, and a secondary verification mechanism can be used for end effector nodes to avoid accidental deletion.

[0059] This invention achieves fully automated node management through a programmed detection mechanism, which not only covers node screening at all skeletal levels, but also processes dynamically generated temporary nodes in real time, fundamentally avoiding joint abnormalities caused by delays in manual operation.

[0060] Through the above technical solution, this invention effectively solves the problem of joint degree-of-freedom conflict caused by unknown node residues during motion capture data-driven processes, eliminating the resulting unnatural shaking and abnormal bending phenomena. The processed skeletal system maintains the uniqueness of constraint relationships, ensuring the stable operation of the single-axis rotation constraint architecture.

[0061] Based on the above-mentioned hierarchical single-axis rotation constraint system, this invention further proposes a hierarchical single-axis rotation constraint method for motion capture data processing, such as... Figure 3As shown, the process includes the following steps: when importing motion capture data, the inverse kinematics of the character is converted into forward kinematics, and the initial movements of the character's waist and legs are adjusted to match the initial state of the motion capture data; the driving bones in the motion capture data are copied to generate an intermediate bone chain, and a corresponding inverse kinematics bone is created based on the intermediate bone chain; an intermediate inverse kinematics bone system is created based on the inverse kinematics bone, and the intermediate inverse kinematics bone system is constrained according to the three-level constraint architecture to achieve single-axis rotation constraint.

[0062] In this context, IK to FK conversion refers to switching the kinematic mode from end-effector-based control to joint chain sequence control during the character skeleton control mode transition. This can be achieved using skeleton rotation angle reset and controller calculation algorithms to eliminate initial posture differences. The intermediate skeleton chain refers to the transitional skeleton structure generated by skeleton replication driven by motion capture data. Specifically, it can be generated using a skeleton replication tool to create a copy with the same topology as the original skeleton, used to isolate the original motion capture data from the constraint system and avoid degree-of-freedom conflicts. The three-level constraint architecture refers to the phased implementation of skeleton control transfer mechanisms. This can be achieved by establishing directional constraints, polar vector constraints, and parent-child constraints at each level, used to decompose multi-axis rotations into single-axis rotations while maintaining motion stability.

[0063] Specifically, during the motion capture data import phase, the character's inverse kinematics control mode is converted to a forward kinematics mode, aligning the initial rotation angles of the character's skeleton with the motion capture data and eliminating posture deviations in the waist and legs. Subsequently, an intermediate skeleton chain is generated by copying the drive skeleton, establishing a transition layer identical to the original motion capture skeleton structure, while simultaneously generating an inverse kinematics skeleton as a constraint manipulation object. During the construction of the intermediate inverse kinematics skeleton system, polar vector constraints are applied to the inverse kinematics control handles using polar vector locators, limiting potentially multi-axis rotations to a single rotation axis. Finally, a three-level constraint architecture is used to progressively transfer control. The first level constraint allows the intermediate skeleton chain to inherit the posture characteristics of the motion capture data; the second level constraint uses polar vector locators to implement single-axis rotation restrictions; and the third level constraint transmits the processed motion to the final controller, thereby eliminating abnormal joint movements while preserving the detailed features of the original motion capture data.

[0064] This method constructs a dual structure of intermediate skeletal chain and inverse kinematic skeleton to form a physically isolated constraint operation space, avoiding degree-of-freedom interference caused by direct constraints. Through a three-level constraint architecture, the multi-axis rotation problem is transformed into single-axis control step by step, and the coordinate system zeroing operation of the polar vector locator is used to eliminate the rotation axis coupling phenomenon.

[0065] Through the above technical solution, the present invention solves the problem of multi-axis superimposed rotation when motion capture data drives character skeletons. It avoids degree-of-freedom conflicts caused by direct constraints by using the physical isolation characteristics of the intermediate skeleton chain. It retains the detailed features of motion capture data by using the hierarchical control transfer mechanism of the three-level constraint architecture. At the same time, it eliminates joint shaking or abnormal bending by using the axial restriction function of the polar vector locator.

[0066] It should be noted that the information interaction and execution process between the above modules / units are based on the same concept as the method embodiments of this application. For details on their specific functions and technical effects, please refer to the method embodiments section, and they will not be repeated here.

[0067] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0068] It should be noted that although several modules or units for the device used to perform actions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to the embodiments of this application, the features and functions of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0069] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Contents not described in detail in this specification belong to prior art known to those skilled in the art.

Claims

1. A hierarchical single-axis rotation constraint system for motion capture data processing, characterized in that: include The data import and processing module is used to convert the character's IK to FK when importing motion capture data, and to adjust the initial movements of the character's waist and legs to be consistent with the initial state of the motion capture data. The skeleton replication module is used to replicate the driving skeletons in the motion capture data to generate an intermediate skeleton chain, and to create the corresponding IK skeleton based on the intermediate skeleton chain; The intermediate IK skeleton system creation module is used to create an intermediate IK skeleton system based on the IK skeleton, and to constrain the intermediate IK skeleton system according to the three-level constraint architecture to achieve single-axis rotation constraint.

2. The hierarchical single-axis rotation constraint system in motion capture data processing according to claim 1, characterized in that: The intermediate skeletal chain includes an initial joint, intermediate joints, and an end joint.

3. The hierarchical single-axis rotation constraint system in motion capture data processing according to claim 1, characterized in that: The IK skeleton includes the IK initiation joint, the IK intermediate joint, and the IK end joint.

4. The hierarchical single-axis rotation constraint system in motion capture data processing according to claim 1, characterized in that, The process of creating the intermediate IK skeleton system is as follows: Select the IK start joint of the IK skeleton as the starting point, and construct the IK control handle together with the IK end joint of the IK skeleton. Use the IK end joint to apply point constraints to the IK control handle, and use the IK end joint to apply directional constraints to the end joints of the intermediate bone chain. Create a polar vector locator, constrain the polar vector locator to the middle joint of the IK skeleton, complete the coordinate system zeroing and preset offset processing of the polar vector locator, use the processed polar vector locator to apply polar vector constraints to the IK handle, and constrain the processed polar vector locator to the middle skeleton chain. Establish the parent-child constraint relationship between the IK starting joint and the processed polar vector positioner.

5. The hierarchical single-axis rotation constraint system in motion capture data processing according to claim 1, characterized in that, The three-level constraint architecture is as follows: Level 1 constraint: motion capture skeleton drives intermediate skeleton chain; Second-level constraint: Construct IK chains separately for key parts, create locators at the intermediate nodes of the IK chains, set the local coordinate system of the locators to zero, and use the processed locators as the polar vector constraint objects of the IK control handles. Level 3 constraint: IK end joint orientation constraint final controller.

6. The hierarchical single-axis rotation constraint system in motion capture data processing according to claim 1, characterized in that: It also includes a finger baking judgment module, which is used to identify the number of finger bones in motion capture data. If the number of finger bones is greater than a set threshold, the finger bones are baked; otherwise, the finger baking step is skipped.

7. The hierarchical single-axis rotation constraint system in motion capture data processing according to claim 1, characterized in that: It also includes a function option module, which provides a programmable configuration interface for specific functions.

8. The hierarchical single-axis rotation constraint system in motion capture data processing according to claim 1, characterized in that: The specific functions include any one or more of chest IK fusion, motion capture data displacement matching, and wrist IK fusion.

9. The hierarchical single-axis rotation constraint system in motion capture data processing according to claim 1, characterized in that: It also includes a node removal module, which is used to automatically identify and clean up unknown nodes after applying motion capture data.

10. A hierarchical single-axis rotation constraint method for motion capture data processing, characterized in that: When importing motion capture data, convert the character's IK to FK and adjust the initial movements of the character's waist and legs to match the initial state of the motion capture data. The driving skeleton in the motion capture data is copied to generate an intermediate skeleton chain, and the corresponding IK skeleton is created based on the intermediate skeleton chain; An intermediate IK skeleton system is created based on the IK skeleton, and a single-axis rotation constraint is achieved by constraining the intermediate IK skeleton system according to the three-level constraint architecture.

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