wip

playground.py

@@ -47,6 +47,7 @@ from matplotlib import pyplot as plt
 from numpy.typing import ArrayLike
 from scipy.optimize import linear_sum_assignment
 from scipy.spatial.transform import Rotation as R
+from typing_extensions import deprecated
 
 from app.camera import (
     Camera,
@@ -349,9 +350,8 @@ display(
 with jnp.printoptions(precision=3, suppress=True):
     display(affinity_matrix)
 
+
 # %%
-
-
 def clusters_to_detections(
     clusters: Sequence[Sequence[int]], sorted_detections: Sequence[Detection]
 ) -> list[list[Detection]]:
@@ -375,6 +375,19 @@ clusters, sol_matrix = solver.solve(aff_np)
 display(clusters)
 display(sol_matrix)
 
+# %%
+T = TypeVar("T")
+
+
+def flatten_values(
+    d: Mapping[Any, Sequence[T]],
+) -> list[T]:
+    """
+    Flatten a dictionary of sequences into a single list of values.
+    """
+    return [v for vs in d.values() for v in vs]
+
+
 # %%
 WIDTH = 2560
 HEIGHT = 1440
@@ -792,6 +805,9 @@ def calculate_tracking_detection_affinity(
 
 
 # %%
+@deprecated(
+    "Use `calculate_camera_affinity_matrix` instead. This implementation has the problem of under-utilizing views from different cameras."
+)
 @beartype
 def calculate_affinity_matrix(
     trackings: Sequence[Tracking],
@@ -880,28 +896,31 @@ def calculate_camera_affinity_matrix(
     lambda_a: float,
 ) -> Float[Array, "T D"]:
     """
-    Calculate an affinity matrix between trackings and detections from a single camera.
+    Vectorized version (with JAX) that computes the affinity matrix between a set
+    of *trackings* and *detections* coming from **one** camera.
 
-    This follows the iterative camera-by-camera approach from the paper
+    The whole computation is done with JAX array operations and `vmap` – no
-    "Cross-View Tracking for Multi-Human 3D Pose Estimation at over 100 FPS".
+    explicit Python ``for``-loops over the (T, D) pairs.  This makes the routine
-    Instead of creating one large matrix for all cameras, this creates
+    fully parallelisable on CPU/GPU/TPU without any extra `jit` compilation.
-    a separate matrix for each camera, which can be processed independently.
 
-    Args:
+    Args
-        trackings: Sequence of tracking objects
+    -----
-        camera_detections: Sequence of detection objects, from the same camera
+    trackings : Sequence[Tracking]
-        w_2d: Weight for 2D affinity
+        Existing 3-D track states (length = T)
-        alpha_2d: Normalization factor for 2D distance
+    camera_detections : Sequence[Detection]
-        w_3d: Weight for 3D affinity
+        Detections from *a single* camera (length = D).  All detections **must**
-        alpha_3d: Normalization factor for 3D distance
+        share the same ``detection.camera`` instance.
-        lambda_a: Decay rate for time difference
+    w_2d, alpha_2d, w_3d, alpha_3d, lambda_a : float
+        Hyper-parameters exactly as defined in the paper (and earlier helper
+        functions).
 
-    Returns:
+    Returns
-        Affinity matrix of shape (T, D) where:
+    -------
-        - T = number of trackings (rows)
+    affinity : jnp.ndarray  (T x D)
-        - D = number of detections from this specific camera (columns)
+        Affinity matrix between each tracking (row) and detection (column).
 
-    Matrix Layout:
+    Matrix Layout
+    -------
     The affinity matrix for a single camera has shape (T, D), where:
     - T = number of trackings (rows)
     - D = number of detections from this camera (columns)
@@ -922,100 +941,107 @@ def calculate_camera_affinity_matrix(
     computed using both 2D and 3D geometric correspondences.
     """
 
-    def verify_all_detection_from_same_camera(detections: Sequence[Detection]):
+    # ----------  Safety checks & early exits  --------------------------------
-        if not detections:
+    if len(trackings) == 0 or len(camera_detections) == 0:
-            return True
+        return jnp.zeros((len(trackings), len(camera_detections)))  # pragma: no cover
-        camera_id = next(iter(detections)).camera.id
-        return all(map(lambda d: d.camera.id == camera_id, detections))
 
-    if not verify_all_detection_from_same_camera(camera_detections):
+    # Ensure all detections come from the *same* camera
-        raise ValueError("All detections must be from the same camera")
+    cam_id_ref = camera_detections[0].camera.id
-
+    if any(det.camera.id != cam_id_ref for det in camera_detections):
-    affinity = jnp.zeros((len(trackings), len(camera_detections)))
+        raise ValueError(
-
+            "All detections given to calculate_camera_affinity_matrix must come from the same camera."
-    for i, tracking in enumerate(trackings):
-        for j, det in enumerate(camera_detections):
-            affinity_value = calculate_tracking_detection_affinity(
-                tracking,
-                det,
-                w_2d=w_2d,
-                alpha_2d=alpha_2d,
-                w_3d=w_3d,
-                alpha_3d=alpha_3d,
-                lambda_a=lambda_a,
-            )
-            affinity = affinity.at[i, j].set(affinity_value)
-
-    return affinity
-
-
-@beartype
-def process_detections_iteratively(
-    trackings: Sequence[Tracking],
-    detections: Sequence[Detection],
-    w_2d: float = 1.0,
-    alpha_2d: float = 1.0,
-    w_3d: float = 1.0,
-    alpha_3d: float = 1.0,
-    lambda_a: float = 0.1,
-) -> list[tuple[int, Detection]]:
-    """
-    Process detections iteratively camera by camera, matching them to trackings.
-
-    This implements the paper's approach where each camera is processed
-    independently, and the affinity matrix is calculated for one camera at a time.
-    This approach has several advantages:
-    1. Computational cost scales linearly with number of cameras
-    2. Can handle non-synchronized camera frames
-    3. More efficient for large-scale camera systems
-
-    Args:
-        trackings: Sequence of tracking objects
-        detections: Sequence of detection objects
-        w_2d: Weight for 2D affinity
-        alpha_2d: Normalization factor for 2D distance
-        w_3d: Weight for 3D affinity
-        alpha_3d: Normalization factor for 3D distance
-        lambda_a: Decay rate for time difference
-
-    Returns:
-        List of (tracking_index, detection) pairs representing matches
-    """
-    # Group detections by camera
-    detection_by_camera = classify_by_camera(detections)
-
-    # Store matches between trackings and detections
-    matches = []
-
-    # Process each camera one by one
-    for camera_id, camera_detections in detection_by_camera.items():
-        # Calculate affinity matrix for this camera only
-        camera_affinity = calculate_camera_affinity_matrix(
-            trackings,
-            camera_detections,
-            w_2d=w_2d,
-            alpha_2d=alpha_2d,
-            w_3d=w_3d,
-            alpha_3d=alpha_3d,
-            lambda_a=lambda_a,
         )
 
-        # Apply Hungarian algorithm for this camera only
+    camera = camera_detections[0].camera  # shared camera object
-        tracking_indices, detection_indices = linear_sum_assignment(
+    cam_w, cam_h = map(int, camera.params.image_size)
-            camera_affinity, maximize=True
+    cam_center = camera.params.location  # (3,)
+
+    # ----------  Pack tracking data into JAX arrays  -------------------------
+    # (T, J, 3)
+    track_kps_3d = jnp.stack([trk.keypoints for trk in trackings])
+
+    # (T, 3) velocity – zero if None
+    velocities = jnp.stack(
+        [
+            (
+                trk.velocity
+                if trk.velocity is not None
+                else jnp.zeros(3, dtype=jnp.float32)
+            )
+            for trk in trackings
+        ]
     )
-        tracking_indices = cast(Sequence[int], tracking_indices)
-        detection_indices = cast(Sequence[int], detection_indices)
 
-        # Add matches to result
+    # (T,) last update timestamps (float seconds)
-        for t_idx, d_idx in zip(tracking_indices, detection_indices):
+    track_last_ts = jnp.array(
-            # Skip matches with zero or negative affinity
+        [trk.last_active_timestamp.timestamp() for trk in trackings]
-            if camera_affinity[t_idx, d_idx] <= 0:
+    )
-                continue
 
-            matches.append((t_idx, camera_detections[d_idx]))
+    # Pre-project 3-D tracking points into 2-D for *this* camera – (T, J, 2)
+    track_proj_2d = jax.vmap(camera.project)(track_kps_3d)
 
-    return matches
+    # ----------  Pack detection data  ----------------------------------------
+    # (D, J, 2)
+    det_kps_2d = jnp.stack([det.keypoints for det in camera_detections])
+
+    # (D,) detection timestamps (float seconds)
+    det_ts = jnp.array([det.timestamp.timestamp() for det in camera_detections])
+
+    # Back-project detection 2-D points to the z=0 plane in world coords – (D, J, 3)
+    det_backproj_3d = camera.unproject_points_to_z_plane(det_kps_2d, z=0.0)
+
+    # ----------  Broadcast / compute pair-wise quantities --------------------
+    # Time differences  Δt  (T, D)  – always non-negative because detections are newer
+    delta_t = jnp.maximum(det_ts[None, :] - track_last_ts[:, None], 0.0)
+
+    # ---------- 2-D affinity --------------------------------------------------
+    # Normalise 2-D points by image size (already handled in helper but easier here)
+    track_proj_norm = track_proj_2d / jnp.array([cam_w, cam_h])  # (T, J, 2)
+    det_kps_norm = det_kps_2d / jnp.array([cam_w, cam_h])  # (D, J, 2)
+
+    # (T, D, J) Euclidean distances in normalised image space
+    dist_2d = jnp.linalg.norm(
+        track_proj_norm[:, None, :, :] - det_kps_norm[None, :, :, :],
+        axis=-1,
+    )
+
+    # (T, D, 1) for broadcasting with J dimension
+    delta_t_exp = delta_t[:, :, None]
+
+    affinity_2d_per_kp = (
+        w_2d
+        * (1.0 - dist_2d / (alpha_2d * jnp.clip(delta_t_exp, a_min=1e-6)))
+        * jnp.exp(-lambda_a * delta_t_exp)
+    )
+    affinity_2d = jnp.sum(affinity_2d_per_kp, axis=-1)  # (T, D)
+
+    # ---------- 3-D affinity --------------------------------------------------
+    # Predict 3-D pose at detection time for each (T, D) pair – (T, D, J, 3)
+    predicted_pose = (
+        track_kps_3d[:, None, :, :]
+        + velocities[:, None, None, :] * delta_t_exp[..., None]
+    )
+
+    # Camera ray for each detection/keypoint – (1, D, J, 3)
+    line_vec = det_backproj_3d[None, :, :, :] - cam_center  # broadcast (T, D, J, 3)
+
+    # Vector from camera centre to predicted point – (T, D, J, 3)
+    vec_cam_to_pred = cam_center - predicted_pose
+
+    # Cross-product norm and distance
+    cross_prod = jnp.cross(line_vec, vec_cam_to_pred)
+    numer = jnp.linalg.norm(cross_prod, axis=-1)  # (T, D, J)
+    denom = jnp.linalg.norm(line_vec, axis=-1)  # (1, D, J) broadcast automatically
+    dist_3d = numer / jnp.clip(denom, a_min=1e-6)
+
+    affinity_3d_per_kp = (
+        w_3d * (1.0 - dist_3d / alpha_3d) * jnp.exp(-lambda_a * delta_t_exp)
+    )
+    affinity_3d = jnp.sum(affinity_3d_per_kp, axis=-1)  # (T, D)
+
+    # ----------  Final affinity ----------------------------------------------
+    affinity_total = affinity_2d + affinity_3d  # (T, D)
+    return affinity_total
 
 
 # %%
@@ -1028,10 +1054,11 @@ ALPHA_3D = 1.0
 
 trackings = sorted(global_tracking_state.trackings.values(), key=lambda x: x.id)
 unmatched_detections = shallow_copy(next_group)
+camera_detections = classify_by_camera(unmatched_detections)
 
-affinity, detection_by_camera = calculate_affinity_matrix(
+affinity = calculate_camera_affinity_matrix(
     trackings,
-    unmatched_detections,
+    next(iter(camera_detections.values())),
     w_2d=W_2D,
     alpha_2d=ALPHA_2D,
     w_3d=W_3D,
@@ -1041,23 +1068,6 @@ affinity, detection_by_camera = calculate_affinity_matrix(
 display(affinity)
 
 
-# %%
-T = TypeVar("T")
-
-
-def flatten_values(
-    d: Mapping[Any, Sequence[T]],
-) -> list[T]:
-    """
-    Flatten a dictionary of sequences into a single list of values.
-    """
-    return [v for vs in d.values() for v in vs]
-
-
-detections_sorted = flatten_values(detection_by_camera)
-display(detections_sorted)
-display(detection_by_camera)
-
 # %%
 # Perform Hungarian algorithm for assignment for each camera
 indices_T, indices_D = linear_sum_assignment(affinity, maximize=True)