trackforge / trackers / ocsort

Module ocsort

OC-SORT: Observation-Centric SORT

This module implements OC-SORT (Observation-Centric SORT), a robust extension of SORT that addresses tracker drift during occlusions by anchoring motion estimation to raw detections rather than Kalman filter predictions.

Algorithm Overview

SORT accumulates prediction errors during occlusions because its Kalman filter integrates noisy velocity estimates when no observation is available. OC-SORT corrects this with two complementary mechanisms:

Observation-Centric Velocity (OCV) Velocity is computed directly from consecutive detections, not from the Kalman filter state. This produces a more reliable momentum signal because it is grounded in actual observations.

Observation-Centric Momentum (OCM) Before IoU matching, a direction-consistency bonus is added to each IoU score based on how well the observed velocity direction aligns with the vector from the track's last observation to each candidate detection. Matches that are consistent with the track's momentum receive a higher effective IoU, improving association after missed frames.

Observation-Centric Re-Update (ORU) When a lost track is re-matched after a gap, the Kalman filter is "re-wound" by replaying linearly interpolated observations between the last seen position and the current detection. This corrects the accumulated drift so that future predictions start from an accurate state.

Parameters

Tuning Tips

• Increase max_age (e.g. 60) when objects undergo long occlusions.
• Increase delta_t for smoother velocity at the cost of responsiveness to rapid direction changes.
• Increase inertia (max 1.0) if objects move at near-constant velocity; lower it for erratic motion.
• min_hits=1 gives immediate track output — useful when detections are already filtered upstream.

References

Observation-Centric SORT: Rethinking SORT for Robust Multi-Object Tracking Jinkun Cao, Xinshuo Weng, Rawal Khirodkar, Jiangmiao Pang, Kris Kitani CVPR 2023 arXiv:2203.14360

Quick Reference

Types

OcSort

struct OcSort {
    // [REDACTED: Private Fields]
}

OC-SORT tracker.

Extends SORT with observation-centric velocity, momentum-adjusted prediction, and Kalman re-update on re-association. The public API is identical to Sort: call [OcSort::update] once per frame with a list of detections.

Example

use trackforge::trackers::ocsort::OcSort;

// max_age=30, min_hits=3, iou_threshold=0.3, delta_t=3, inertia=0.2
let mut tracker = OcSort::new(30, 3, 0.3, 3, 0.2);

let detections = vec![
    ([100.0_f32, 100.0, 50.0, 100.0], 0.9_f32, 0_i64),
    ([200.0_f32, 200.0, 60.0, 120.0], 0.85_f32, 0_i64),
];

let tracks = tracker.update(detections);
for t in &tracks {
    println!("ID: {}, Box: {:?}", t.track_id, t.tlwh);
}

Implementations

fn new(max_age: usize, min_hits: usize, iou_threshold: f32, delta_t: usize, inertia: f32) -> Self

Create a new OC-SORT tracker.

# Arguments

fn from_params(params: OcSortParams) -> Self

Create an OC-SORT tracker from an OcSortParams.

fn update(&mut self, detections: Vec<([f32; 4], f32, i64)>) -> Vec<OcSortTrack>

Update the tracker with detections for the current frame.

# Arguments

# Returns

Confirmed tracks active in this frame.

Trait Implementations

impl Default for OcSort

fn default() -> Self

fn to_subset(&self) -> Option<SS>

fn is_in_subset(&self) -> bool

fn to_subset_unchecked(&self) -> SS

fn from_subset(element: &SS) -> SP

impl Tracker for OcSort

• type Track = ObsTrack

fn update(&mut self, detections: Vec<crate::traits::Detection>) -> Vec<OcSortTrack>

OcSortParams

struct OcSortParams {
    pub common: crate::trackers::common::CommonParams,
    pub iou_threshold: f32,
    pub delta_t: usize,
    pub inertia: f32,
}

Settings for OcSort.

Shared lifecycle fields live in CommonParams; the fields below are specific to OC-SORT. Build it with default and pass it to [OcSort::from_params].

Fields

Trait Implementations

impl Clone for OcSortParams

fn clone(&self) -> OcSortParams

impl Copy for OcSortParams

impl Debug for OcSortParams

fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result

impl Default for OcSortParams

fn default() -> Self

impl PartialEq for OcSortParams

fn eq(&self, other: &OcSortParams) -> bool

fn to_subset(&self) -> Option<SS>

fn is_in_subset(&self) -> bool

fn to_subset_unchecked(&self) -> SS

fn from_subset(element: &SS) -> SP

OcSortTrack

type OcSortTrack = crate::trackers::common::ObsTrack;

A single tracked object managed by OC-SORT.

Alias of the shared observation-centric ObsTrack, which carries the Kalman state and observation history that OC-SORT's velocity (OCM) and re-update (ORU) logic operate on.

OcSortTrackState

type OcSortTrackState = crate::trackers::common::TrackState;

Track lifecycle state for OC-SORT.

Alias of the shared TrackState.