facebookresearch/momentum
Mar 2025 – Oct 2025
6 Months active
Languages Used
C++PythonYAML
Technical Skills
Algorithm OptimizationC++ DevelopmentDebuggingMultithreadingPerformance OptimizationSoftware Testing
Carsten Stoll
PROFILE
Carsten Stoll
Christian Stoll contributed to the facebookresearch/momentum repository by developing and refining core features for 3D animation, geometry processing, and motion capture calibration. He implemented multi-threaded optimization routines in C++ to accelerate constraint solving, enhanced mesh self-intersection detection using both brute-force and BVH methods with Python bindings, and improved calibration workflows with pose priors and robust frame sampling. Stoll addressed numerical stability in quaternion-to-Euler conversions and expanded support for asset formats like FBX and GLB. His work emphasized test-driven development, cross-language integration with Pybind11, and robust CI/CD practices, resulting in more reliable, maintainable, and scalable motion processing pipelines.
Overall Statistics
Feature vs Bugs
70%Features
Repository Contributions
24Total
Bugs
6
Commits
24
Features
14
Lines of code
4,218
Activity Months6
Your Network
2284 people
Work History
October 2025
5 Commits • 3 Features
Oct 1, 2025Month: 2025-10 momentum contributions focused on delivering reliability in asset loading, robustness in the solver, and enriched animation capabilities. Delivered key features with accompanying tests and resolved a critical error-calc bug affecting geometry processing.
5 Commits • 3 Features
Oct 1, 2025Month: 2025-10 momentum contributions focused on delivering reliability in asset loading, robustness in the solver, and enriched animation capabilities. Delivered key features with accompanying tests and resolved a critical error-calc bug affecting geometry processing.
October 2025
August 2025
2 Commits • 1 Features
Aug 1, 20252025-08 monthly summary for facebookresearch/momentum: Delivered improvements to constraint management in Solver2 and fixed GLB identity handling to ensure consistent identity mapping and loading. These changes improve stability and predictability of motion vector processing, enhance solver state management, and reduce risk of incorrect scaling parameter application when motion data is absent.
August 2025
2 Commits • 1 Features
Aug 1, 20252025-08 monthly summary for facebookresearch/momentum: Delivered improvements to constraint management in Solver2 and fixed GLB identity handling to ensure consistent identity mapping and loading. These changes improve stability and predictability of motion vector processing, enhance solver state management, and reduce risk of incorrect scaling parameter application when motion data is absent.
July 2025
5 Commits • 3 Features
Jul 1, 2025July 2025 monthly summary for facebookresearch/momentum focused on delivering impactful calibration improvements, API enhancements, and developer usability gains. The work emphasizes business value through faster, more reliable motion calibration and easier maintenance of geometric representations and error-function workflows.
5 Commits • 3 Features
Jul 1, 2025July 2025 monthly summary for facebookresearch/momentum focused on delivering impactful calibration improvements, API enhancements, and developer usability gains. The work emphasizes business value through faster, more reliable motion calibration and easier maintenance of geometric representations and error-function workflows.
July 2025
May 2025
5 Commits • 3 Features
May 1, 2025May 2025 monthly summary — facebookresearch/momentum Key features delivered: - Mesh Self-Intersection Detection: implemented brute-force and BVH-based detection with a Python wrapper and comprehensive unit tests to validate intersecting face pairs from Python. Commits: bb974a0d18428e3bca45fb557802d331e7e60de4; dc7940d41c5de6ca3b6adc04e40c742b12069074. - Marker Tracker Calibration Enhancements: reintroduced pose priors and first-frame floor constraints in the marker solver, and added a greedy frame sampling method to capture frames with maximal pose variance. Commits: 736c8b9dcc2f98bc4038944a8fecfec795d739a5; a442b1efff3790185ce36ff9e09c67f677796f61. - Vertex Projection Error Function for Inverse Kinematics in pymomentum: introduced a vertex projection error function with C++/Python implementations, solver integration, and tests. Commit: 59406a4e087fe04a71f9ac6eca3077c0af335c14. Major bugs fixed: - No separate bug-fix-only commits identified for May 2025; bug-fixes were incorporated within feature work and associated tests, contributing to overall reliability improvements. Overall impact and accomplishments: - Strengthened geometry processing reliability and validation through robust mesh intersection testing. - Enhanced calibration workflows with pose priors, floor constraints, and variance-maximizing frame sampling, reducing calibration time while increasing accuracy. - Improved inverse kinematics accuracy in pymomentum via a dedicated vertex projection error function, enabling more realistic pose estimation. Technologies/skills demonstrated: - C++ and Python developer tooling, cross-language bindings, BVH-based acceleration, solver integration, and test-driven development.
May 2025
5 Commits • 3 Features
May 1, 2025May 2025 monthly summary — facebookresearch/momentum Key features delivered: - Mesh Self-Intersection Detection: implemented brute-force and BVH-based detection with a Python wrapper and comprehensive unit tests to validate intersecting face pairs from Python. Commits: bb974a0d18428e3bca45fb557802d331e7e60de4; dc7940d41c5de6ca3b6adc04e40c742b12069074. - Marker Tracker Calibration Enhancements: reintroduced pose priors and first-frame floor constraints in the marker solver, and added a greedy frame sampling method to capture frames with maximal pose variance. Commits: 736c8b9dcc2f98bc4038944a8fecfec795d739a5; a442b1efff3790185ce36ff9e09c67f677796f61. - Vertex Projection Error Function for Inverse Kinematics in pymomentum: introduced a vertex projection error function with C++/Python implementations, solver integration, and tests. Commit: 59406a4e087fe04a71f9ac6eca3077c0af335c14. Major bugs fixed: - No separate bug-fix-only commits identified for May 2025; bug-fixes were incorporated within feature work and associated tests, contributing to overall reliability improvements. Overall impact and accomplishments: - Strengthened geometry processing reliability and validation through robust mesh intersection testing. - Enhanced calibration workflows with pose priors, floor constraints, and variance-maximizing frame sampling, reducing calibration time while increasing accuracy. - Improved inverse kinematics accuracy in pymomentum via a dedicated vertex projection error function, enabling more realistic pose estimation. Technologies/skills demonstrated: - C++ and Python developer tooling, cross-language bindings, BVH-based acceleration, solver integration, and test-driven development.
April 2025
5 Commits • 3 Features
Apr 1, 2025April 2025: In facebookresearch/momentum, delivered four focused improvements to robustness, accuracy, and developer productivity. 1) Vertex Error Function Refinement: refactored to separate serial and parallel execution paths, added a dedicated parallel test to ensure accurate error evaluation, improving reliability of vertex error calculations. 2) Vertex Projection Error Function: introduced 2D losses for skinned vertices, plus skinning weight iterator and tests; updated error thresholds for better convergence and stability. 3) CI Workflow Enhancement: enabled workflow_dispatch across macOS, Ubuntu, and Windows for on-demand testing. 4) Quaternion to Euler Instability Fix: clamped asin input to [-1, 1] to fix numerical instability, with tests. These changes reduce NaN edge cases, improve test coverage, and empower on-demand validation, delivering business value by increasing model robustness and reducing debugging time.
5 Commits • 3 Features
Apr 1, 2025April 2025: In facebookresearch/momentum, delivered four focused improvements to robustness, accuracy, and developer productivity. 1) Vertex Error Function Refinement: refactored to separate serial and parallel execution paths, added a dedicated parallel test to ensure accurate error evaluation, improving reliability of vertex error calculations. 2) Vertex Projection Error Function: introduced 2D losses for skinned vertices, plus skinning weight iterator and tests; updated error thresholds for better convergence and stability. 3) CI Workflow Enhancement: enabled workflow_dispatch across macOS, Ubuntu, and Windows for on-demand testing. 4) Quaternion to Euler Instability Fix: clamped asin input to [-1, 1] to fix numerical instability, with tests. These changes reduce NaN edge cases, improve test coverage, and empower on-demand validation, delivering business value by increasing model robustness and reducing debugging time.
April 2025
March 2025
2 Commits • 1 Features
Mar 1, 20252025-03 Monthly Summary Key deliverables: - VertexErrorFunction: Added a maxThreads option to getGradient and getJacobian to enable multi-threading, improving performance for higher constraint counts (default 0 for serial execution). Commit c30d1694e2920503e22ed5577acf954e9c40f20c (#227). - Solver test reliability: Stabilized tests by adjusting constraint weights and improving random normal vector generation to prevent high error values, yielding robust and deterministic results. Commit 84cd3a4aa243ed0b7de304e36462bfccbf1a5580 (#244). Major bugs fixed: - Reduced intermittent solver test failures; improved test determinism across environments. Overall impact and accomplishments: - Performance uplift for optimization with larger constraint sets; improved reliability and CI readiness; supports scaling Momentum usage in production. Technologies/skills demonstrated: - Parallel computation design and integration (maxThreads), numerical optimization, testing discipline, and traceability with commits.
March 2025
2 Commits • 1 Features
Mar 1, 20252025-03 Monthly Summary Key deliverables: - VertexErrorFunction: Added a maxThreads option to getGradient and getJacobian to enable multi-threading, improving performance for higher constraint counts (default 0 for serial execution). Commit c30d1694e2920503e22ed5577acf954e9c40f20c (#227). - Solver test reliability: Stabilized tests by adjusting constraint weights and improving random normal vector generation to prevent high error values, yielding robust and deterministic results. Commit 84cd3a4aa243ed0b7de304e36462bfccbf1a5580 (#244). Major bugs fixed: - Reduced intermittent solver test failures; improved test determinism across environments. Overall impact and accomplishments: - Performance uplift for optimization with larger constraint sets; improved reliability and CI readiness; supports scaling Momentum usage in production. Technologies/skills demonstrated: - Parallel computation design and integration (maxThreads), numerical optimization, testing discipline, and traceability with commits.
Activity
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Quality Metrics
Correctness92.0%
Maintainability89.2%
Architecture88.8%
Performance83.0%
AI Usage20.0%
Skills & Technologies
Programming Languages
C++PythonYAML
Technical Skills
3D Animation3D Graphics3D Math3D Model HandlingAlgorithm AnalysisAlgorithm DevelopmentAlgorithm OptimizationC++C++ DevelopmentCI/CDCalibrationCharacter AnimationComputational GeometryComputer VisionData Serialization
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