Keyframe motion capture method based on joint puppet
By using a keyframe motion capture method based on articulated puppets, the problems of high cost, complex operation, inaccurate data, and poor compatibility in existing technologies are solved, achieving simple, accurate, and natural motion capture, which is suitable for animation production and game character driving.
Patent Information
- Application Number
- CN202511809279.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-03
- Publication Date
- 2026-03-03
AI Technical Summary
Existing motion capture technology is expensive, cumbersome to operate, susceptible to interference during data collection, lacks accuracy in motion data, produces unnatural motion reconstructions, has poor compatibility, and is difficult to meet the needs of ordinary users.
A multi-degree-of-freedom articulated puppet is used, equipped with high-precision sensors and a data transmission module to collect and calibrate joint motion data in real time. Complete motion data is generated through keyframe acquisition, preprocessing, and interpolation algorithms, and combined with physical constraint verification to output a compatible format.
It achieves motion capture that is easy to operate, accurate in data, produces natural movements, and has strong compatibility, improving motion capture efficiency and applicability, and meeting the needs of animation production and game character driving.
Smart Images
Figure CN121600136A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of motion capture technology, and more specifically to a keyframe motion capture method based on articulated puppets. Background Technology
[0002] Currently, motion capture technology is widely used in animation production, game character driving, and other related scenarios. However, existing technologies generally have many limitations. Some technologies rely on relatively complex professional equipment and specially constructed venues, resulting in high costs and cumbersome operation processes, failing to meet the needs of ordinary users. Furthermore, some technologies are easily affected by other factors during data acquisition, leading to insufficient accuracy in the acquired motion data. They often lack effective data processing methods to adequately filter noise and fill in missing information, thus affecting the accuracy of motion reproduction. Simultaneously, many technologies do not fully consider the physical constraints of joint movement in the generated motion data, resulting in unnatural reconstructed movements. Moreover, the output format compatibility is poor, easily leading to malfunctions when transmitting and using different devices and software, limiting the promotion and application development of motion capture technology. Therefore, there is a need to develop a motion capture method that is easy to operate, provides accurate data, produces natural movements, and has strong compatibility. Summary of the Invention
[0003] The purpose of this invention is to provide a keyframe motion capture method for articulated puppets that can solve the above-mentioned problems.
[0004] To achieve the above objectives, the present invention provides the following technical solution:
[0005] A keyframe motion capture method based on articulated puppets includes the following steps:
[0006] S1. Hardware system setup: Select a puppet with multiple degrees of freedom joints as the motion capture carrier, install angle sensors and position sensors at the key joints of the puppet, connect the sensors to the computer terminal through the data transmission module, build a real-time data acquisition link, install motion capture control software on the computer terminal and complete the calibration of the sensors and software, so that the software can identify and map the motion data of each joint of the puppet in real time and establish a one-to-one correspondence between the puppet joints and the virtual joints of the software.
[0007] S2. Keyframe Acquisition: Manually drive the joint puppet to adjust to the key posture of the target action. Then, trigger the keyframe acquisition command through the control software to record the joint sensor data. In addition, acquire multiple keyframes in sequence according to the action sequence logic, and then label the sequence number and action feature description. The software automatically stores the keyframe data in a standardized format to generate a keyframe database.
[0008] S3. Keyframe data preprocessing: Noise filtering is performed on the raw keyframe data. Based on the timestamp of the first keyframe, the time parameters of all subsequent keyframes are adjusted to ensure the consistency of the timeline of the action sequence. Missing values in the keyframe data are detected to ensure the integrity of the joint data of each keyframe.
[0009] S4. Motion Interpolation and Complete Motion Generation: Based on the preprocessed keyframe data, an interpolation algorithm is used to generate transition frames between adjacent keyframes. The motion range of the interpolated transition frames is verified by combining the physical motion constraints of the puppet joints. The keyframes and transition frames are integrated into a complete motion data sequence according to the time sequence. After previewing in the software, the user can manually fine-tune the motion to meet the user's expectations.
[0010] S5. Motion Data Output and Verification: Export the complete motion data sequence to an animation software-compatible format, compare the original motion with the virtual motion using motion playback software, detect the consistency of joint movement trajectory and motion rhythm, and also check the compatibility of the data on different devices to ensure that the data is not lost or the format is correct.
[0011] Preferably, in step S1, the key joints of the puppet include the shoulder joint, elbow joint, hip joint, and knee joint.
[0012] Preferably, in step S1: the angle error of the angle sensor does not exceed 0.1°, and the position error of the position sensor does not exceed 0.1mm.
[0013] Preferably, in step S1: the data transmission module is a Bluetooth 5.0 module or a USB-C module, and the data transmission rate is ensured to be no less than 100Hz.
[0014] Preferably, in step S2, the time interval setting between adjacent keyframes includes: 0.5-1s for simple actions and 0.2-0.5s for complex actions.
[0015] Preferably, in step S2: the standardized data storage format is JSON or FBX format, and the keyframe database contains the joint ID, angle value, position coordinates, and acquisition timestamp information of each keyframe.
[0016] Preferably, in step S2: the key posture includes the starting point, turning point, and ending point of the action.
[0017] Preferably, step S3 uses a Kalman filter algorithm to remove outliers caused by sensor jitter, retains valid motion data, and ensures that the data fluctuation amplitude is controlled within the allowable error range.
[0018] Preferably, in step S4: the interpolation algorithm adopts the Bezier curve interpolation algorithm to generate transition frames between adjacent key frames. The number of transition frames is set according to the smoothness requirements of the action. Usually, 5-10 transition frames are generated between each adjacent key frame to make the joint movement trajectory continuous and without lag.
[0019] Preferably, in step S4, the physical movement constraints of the puppet joints include: a maximum bending angle of 140° for the elbow joint and the inability of the knee joint to bend in the opposite direction.
[0020] Beneficial effects
[0021] This invention, through sensor calibration and data preprocessing, can filter out noise, fill in missing data, and improve the accuracy of motion data capture. Simultaneously, it combines joint physical constraints to generate transition frames, avoiding unnatural movements of the target and making the reconstructed motion smoother and more realistic. Furthermore, the output format set by this invention is compatible with mainstream animation software and has high compatibility, enabling its application in animation production, game character driving, and other scenarios. This not only improves motion capture efficiency but also expands the scope of application of the technology, meeting the demand for high-quality motion capture in related fields.
[0022] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the method of the present invention; Detailed Implementation
[0024] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of the present invention, it should be noted that unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances. Furthermore, the technical features involved in the different embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.
[0025] like Figure 1 As shown, a keyframe motion capture method based on articulated puppets includes the following implementation steps:
[0026] I. Hardware System Setup:
[0027] A puppet with multiple degrees of freedom joints was selected as the motion capture carrier. The puppet can be made using 3D printing materials and manufactured using 3D printing technology. High-precision angle and position sensors with an angle error of no more than 0.1° and a position error of no more than 0.1mm were installed at key joints of the puppet, such as the shoulder, elbow, hip, and knee joints. Furthermore, the sensors can be connected to a computer terminal via Bluetooth 5.0 or USB-C data transmission modules to establish a real-time data acquisition link, ensuring that the sensor data transmission rate is no less than 100Hz to avoid data delay. After installing motion capture control software on the computer terminal, the sensors and software can be calibrated, enabling the software to identify and map the motion data of each joint of the puppet in real time, ultimately establishing a one-to-one correspondence between the puppet joints and the virtual joints in the software.
[0028] II. Keyframe Acquisition
[0029] The jointed puppet is manually driven and adjusted to the key poses of the target action, such as the start point, turning point, and end point of the action. After the pose is stable, the keyframe acquisition command is triggered through the control software to record the angle and position data of each joint sensor. Then, multiple keyframes are acquired sequentially according to the action sequence logic. The time interval between adjacent keyframes is set according to the complexity of the action: the time interval between adjacent keyframes is set to 0.5 to 1 second for simple actions and 0.2 to 0.5 seconds for complex actions. At the same time, each keyframe is labeled with a sequence number and action feature description in the software, such as "hand raise start" and "leg kick peak". After the acquisition is completed, the software automatically stores the keyframe data in a standardized JSON or FBX format to generate a keyframe database. The keyframe database contains information such as joint ID, angle value, position coordinates, and acquisition timestamp.
[0030] III. Keyframe Data Preprocessing
[0031] The acquired keyframe raw data is noise filtered using a Kalman filter algorithm to remove outliers caused by sensor jitter, retain valid motion data, and ensure that data fluctuations are controlled within the allowable error range. Then, data alignment is performed: the time parameters of all subsequent keyframes are adjusted based on the timestamp of the first keyframe to ensure the time axis of the action sequence is consistent and to avoid motion misalignment caused by acquisition delay. If a joint data is missing, it is completed by linear interpolation of the joint data in adjacent keyframes to ensure the integrity of joint data in each keyframe.
[0032] IV. Motion Interpolation and Complete Motion Generation
[0033] Based on the preprocessed keyframe data, and using the Bézier curve interpolation algorithm, transition frames are generated between each adjacent keyframe. The number of transition frames is set according to the smoothness requirements of the motion, usually 5-10 transition frames are generated between each adjacent keyframe. Combined with the physical motion constraints of the puppet joints, such as: the maximum bending angle is 140°, and the knee joint cannot bend backwards, the motion range of the interpolated transition frames is checked. If the joint angle of a transition frame exceeds the constraint, it is automatically adjusted to a reasonable range. Then, the keyframes and transition frames are integrated in time sequence to generate a complete motion data sequence. The motion effect can be previewed through the software, and the user can also manually fine-tune the relevant joint parameters until the motion meets the user's expectations.
[0034] V. Motion Data Output and Verification
[0035] The complete motion data sequence is exported to a format compatible with mainstream animation software, such as FBX or BVH, for use in animation production or game character driving scenarios. Then, the original puppet motion is compared with the generated virtual motion using motion playback software to check the consistency of joint movement trajectory and motion rhythm. At the same time, the compatibility of motion data is checked on different devices such as animation workstations or game engines to ensure that there is no data loss or format error.
[0036] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0037] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A keyframe motion capture method based on articulated puppets, characterized in that, Includes the following steps: S1. Hardware system setup: Select a puppet with multiple degrees of freedom joints as the motion capture carrier, install angle sensors and position sensors at the key joints of the puppet, connect the sensors to the computer terminal through the data transmission module, build a real-time data acquisition link, install motion capture control software on the computer terminal and complete the calibration of the sensors and software, so that the software can identify and map the motion data of each joint of the puppet in real time and establish a one-to-one correspondence between the puppet joints and the virtual joints of the software. S2. Keyframe Acquisition: Manually drive the joint puppet to adjust to the key posture of the target action. Then, trigger the keyframe acquisition command through the control software to record the joint sensor data. In addition, acquire multiple keyframes in sequence according to the action sequence logic, and then label the sequence number and action feature description. The software automatically stores the keyframe data in a standardized format to generate a keyframe database. S3. Keyframe data preprocessing: Noise filtering is performed on the raw keyframe data. Based on the timestamp of the first keyframe, the time parameters of all subsequent keyframes are adjusted to ensure the consistency of the timeline of the action sequence. Missing values in the keyframe data are detected to ensure the integrity of the joint data of each keyframe. S4. Motion Interpolation and Complete Motion Generation: Based on the preprocessed keyframe data, an interpolation algorithm is used to generate transition frames between adjacent keyframes. The motion range of the interpolated transition frames is verified by combining the physical motion constraints of the puppet joints. The keyframes and transition frames are integrated into a complete motion data sequence according to the time sequence. After previewing in the software, the user can manually fine-tune the motion to meet the user's expectations. S5. Motion Data Output and Verification: Export the complete motion data sequence to an animation software-compatible format, compare the original motion with the virtual motion using motion playback software, detect the consistency of joint movement trajectory and motion rhythm, and also check the compatibility of the data on different devices to ensure that the data is not lost or the format is correct.
2. The keyframe motion capture method based on an articulated puppet as described in claim 1, characterized in that, In step S1: the key joints of the puppet include the shoulder joint, elbow joint, hip joint, and knee joint.
3. The keyframe motion capture method based on an articulated puppet as described in claim 1, characterized in that, In step S1: the angle error of the angle sensor does not exceed 0.1°, and the position error of the position sensor does not exceed 0.1mm.
4. The keyframe motion capture method based on an articulated puppet as described in claim 1, characterized in that, In step S1: the data transmission module is a Bluetooth 5.0 module or a USB-C module, and the data transmission rate is ensured to be no less than 100Hz.
5. The keyframe motion capture method based on an articulated puppet as described in claim 1, characterized in that, In step S2, the time interval between adjacent keyframes is set as follows: 0.5-1s for simple actions and 0.2-0.5s for complex actions.
6. The keyframe motion capture method based on an articulated puppet as described in claim 1, characterized in that, In step S2: the standardized data storage format is JSON or FBX format, and the keyframe database contains the joint ID, angle value, position coordinates, and acquisition timestamp information of each keyframe.
7. The keyframe motion capture method based on an articulated puppet as described in claim 1, characterized in that, In step S2: the key postures include the starting point, turning point, and ending point of the action.
8. The keyframe motion capture method based on an articulated puppet as described in claim 1, characterized in that, Step S3 uses a Kalman filter algorithm to remove outliers caused by sensor jitter, retains valid motion data, and ensures that the data fluctuation amplitude is controlled within the allowable error range.
9. The keyframe motion capture method based on an articulated puppet as described in claim 1, characterized in that, In step S4: the interpolation algorithm adopts the Bezier curve interpolation algorithm to generate transition frames between adjacent key frames. The number of transition frames is set according to the smoothness requirements of the action. Usually, 5-10 transition frames are generated between each adjacent key frame to make the joint movement trajectory continuous and without lag.
10. The keyframe motion capture method based on an articulated puppet as described in claim 1, characterized in that, In step S4, the physical movement constraints of the puppet joints include: the maximum bending angle of the elbow joint is 140°, and the knee joint cannot bend in the opposite direction.