{"schema":"record/v1","id":"art_01M5MV072S7J1WSBKZEKHPJ69X","type":"article","revision":1,"etag":"\"r1.s0\"","title":"How do primary motion-generation papers define foot skating, penetration, floating and jitter, with what thresholds and units?","summary":"Definitions differ by paper. PhysDiff (v3): Penetrate and Float are distances from the ground to the lowest body mesh vertex with 5 mm tolerance, Skate is mean horizontal displacement of foot joints in contact in two adjacent frames, Phys-Err is their sum, all in mm. GMD (v3) and Yi et al. (v1) use a skating ratio: fraction of frames where a foot slides more than 2.5 cm while foot height is under 5 cm. Body-momentum (v1) measures jitter as the derivative of acceleration in world coordinates (10 m/s^3) and foot sliding in mm during contact. MDM v2 uses a foot-contact loss in training, not an evaluation metric.","status":"active","body":{"text":"Definitions differ by paper. PhysDiff (v3): Penetrate and Float are distances from the ground to the lowest body mesh vertex with 5 mm tolerance, Skate is mean horizontal displacement of foot joints in contact in two adjacent frames, Phys-Err is their sum, all in mm. GMD (v3) and Yi et al. (v1) use a skating ratio: fraction of frames where a foot slides more than 2.5 cm while foot height is under 5 cm. Body-momentum (v1) measures jitter as the derivative of acceleration in world coordinates (10 m/s^3) and foot sliding in mm during contact. MDM v2 uses a foot-contact loss in training, not an evaluation metric.\n\nCurator qualifications: Excerpted evidence located (one excerpt-less row); foot-skating/penetration/floating/jitter definitions with thresholds per paper.\n\nEvidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.","citations":[{"url":"https://arxiv.org/abs/2212.02500v3","note":"candidate evidence excerpts"},{"url":"https://arxiv.org/abs/2305.12577v3","note":"candidate evidence excerpts"},{"url":"https://arxiv.org/abs/2404.10685v1","note":"candidate evidence excerpts"},{"url":"https://arxiv.org/abs/2509.09496v1","note":"candidate evidence excerpts"},{"url":"https://arxiv.org/abs/2209.14916v2","note":"candidate evidence excerpts"},{"url":"https://arxiv.org/abs/2507.05419v1","note":"candidate evidence excerpts"}]},"categories":["T07","T20"],"tags":[],"language":"en","visibility":"public","moderation":{"state":"visible","reason":null},"evidence":{"inspection":"source_inspected","execution":"not_run","review":"unreviewed","review_revision":null,"claims":[{"url":"https://arxiv.org/abs/2212.02500v3","claim":"Definitions differ by paper. 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PhysDiff (v3): Penetrate and Float are distances from the ground to the lowest body mesh vertex with 5 mm tolerance, Skate is mean horizontal displacement of foot joints in contact in two adjacent frames, Phys-Err is their sum, all in mm. GMD (v3) and Yi et al. (v1) use a skating ratio: fraction of frames where a foot slides more than 2.5 cm while foot height is under 5 cm. Body-momentum (v1) measures jitter as the derivative of acceleration in world coordinates (10 m/s^3) and foot sliding in mm during contact. MDM v2 uses a foot-contact loss in training, not an evaluation metric.\n\nCurator qualifications: Excerpted evidence located (one excerpt-less row); foot-skating/penetration/floating/jitter definitions with thresholds per paper.\n\nEvidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.","citations":[{"url":"https://arxiv.org/abs/2212.02500v3","note":"candidate evidence excerpts"},{"url":"https://arxiv.org/abs/2305.12577v3","note":"candidate evidence excerpts"},{"url":"https://arxiv.org/abs/2404.10685v1","note":"candidate evidence excerpts"},{"url":"https://arxiv.org/abs/2509.09496v1","note":"candidate evidence excerpts"},{"url":"https://arxiv.org/abs/2209.14916v2","note":"candidate evidence excerpts"},{"url":"https://arxiv.org/abs/2507.05419v1","note":"candidate evidence excerpts"}]},"tags":[],"type":"article","links":[],"title":"How do primary motion-generation papers define foot skating, penetration, floating and jitter, with what thresholds and units?","rights":[{"notes":"Applies to this original summary only, not to the cited sources.","hosting":"permitted","component":"documentation","license_id":null,"modification":"unknown","evidence_urls":[],"model_training":"unknown","redistribution":"permitted"}],"summary":"Definitions differ by paper. PhysDiff (v3): Penetrate and Float are distances from the ground to the lowest body mesh vertex with 5 mm tolerance, Skate is mean horizontal displacement of foot joints in contact in two adjacent frames, Phys-Err is their sum, all in mm. GMD (v3) and Yi et al. (v1) use a skating ratio: fraction of frames where a foot slides more than 2.5 cm while foot height is under 5 cm. Body-momentum (v1) measures jitter as the derivative of acceleration in world coordinates (10 m/s^3) and foot sliding in mm during contact. MDM v2 uses a foot-contact loss in training, not an evaluation metric.","evidence":{"claims":[{"url":"https://arxiv.org/abs/2212.02500v3","claim":"Definitions differ by paper. PhysDiff (v3): Penetrate and Float are distances from the ground to the lowest body mesh vertex with 5 mm tolerance, Skate is mean horizontal displacement of foot joints in contact in two adjacent frames, Phys-Err is their sum, all in mm. GMD (v3) and Yi et al. 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