Articulated pose estimation using tangent space approximations
Bibliographic record
Abstract
We describe an algorithm to estimate the pose of a generic articulated object. Our algorithm takes as input a description of the object and a potentially incomplete series of observations; it outputs an on-line estimate of the object’s configuration. This task is challenging because: (1) the distribution of object states is often multi-modal; (2) the object is not assumed to be under our control, limiting our ability to predict its motion; and (3) rotational joints make the state space highly non-linear. The proposed method represents three principal contributions to address these challenges. First, we use a particle filter implementation which is unique in that it does not require a reliable state transition model. Instead, the method relies primarily on observations during particle proposal, using the state transition model only at singularities. Second, our particle filter formulation explicitly handles missing observations via a novel proposal mechanism. Although existing particle filters can handle missing observations, they do so only by relying on good state transition models. Finally, our method evaluates noise in the observation space, rather than state space. This reduces the variability in performance due to choice of parametrization and effectively handles non-linearities caused by rotational joints. We compare our method to a baseline implementation without these techniques and demonstrate, for a fixed error, more than an order-of-magnitude reduction in the number of required particles, an increase in the number of effective particles, and an increase in frame rate. We examine the effects of errors in the kinematic model and demonstrate a reduced dependence on state parametrization. The novel use of a precision matrix allows observations which do not provide complete 6-DOF pose information to be processed. Source code for the method is available at http://rvsn.csail.mit.edu/articulated .
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.005 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".