build_gt_from_3dfront.py

#!/usr/bin/env python
"""Build per-view GT (instance mask + object meshes) for the Fire3D single_image
scenes by aligning the source 3D-FRONT room to each annotation and ray-casting it
into the annotation camera.

Pipeline per scene (see the discussion in the task):
  1. shortlist candidate 3D-FRONT rooms whose furniture-model UUID set covers the
     annotation's objects (index built from the ``*_full.glb`` scene graphs);
  2. estimate the glb->annotation-world similarity transform with a RANSAC over
     per-model candidate matches (robust to duplicate models / extra room objects);
  3. for the top-K candidates, ray-cast the placed room objects through the
     annotation intrinsics and keep the room whose rendered depth best agrees with
     the dataset metric depth;
  4. write outputs: uint16 instance mask (full-res, aligned to rgb), id->object
     json, per-object meshes (PLY, OpenCV camera frame = the sceneobjgt frame),
     merged scene-objects mesh, and an rgb overlay for eyeballing the match.

Objects only: walls / floor / ceiling are intentionally skipped.
"""
from __future__ import annotations

import argparse
import glob
import json
import os
import re
import warnings
from itertools import combinations, product
from typing import Any

import numpy as np
import trimesh
from PIL import Image

warnings.filterwarnings("ignore")

UUID_RE = re.compile(r"([0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12})")
SCENE_ROOT = "/mnt/task_runtime/3d-front/3D-FRONT-SCENE"
SI_ROOT = "/mnt/task_runtime/data/single_image"
CV2GL = np.diag([1.0, -1.0, -1.0])                       # OpenCV cam <-> OpenGL cam
CANONICAL_R = np.array([[1.0, 0, 0], [0, 0, -1.0], [0, 1.0, 0]])  # glb y-up -> world z-up
PALETTE = np.array([
    [230, 25, 75], [60, 180, 75], [255, 225, 25], [0, 130, 200], [245, 130, 48],
    [145, 30, 180], [70, 240, 240], [240, 50, 230], [210, 245, 60], [250, 190, 212],
    [0, 128, 128], [220, 190, 255], [170, 110, 40], [255, 250, 200], [128, 0, 0],
    [170, 255, 195], [128, 128, 0], [255, 215, 180], [0, 0, 128], [128, 128, 128],
], dtype=np.uint8)


def umeyama(src: np.ndarray, dst: np.ndarray, fixed_r: np.ndarray | None = None
            ) -> tuple[float, np.ndarray, np.ndarray]:
    """Fit a similarity transform ``dst ~= s * R @ src + t`` (Umeyama, 1991).

    If ``fixed_r`` is given the rotation is held fixed and only scale/translation
    are estimated (used when only two correspondences are available).
    """
    mu_s, mu_d = src.mean(0), dst.mean(0)
    s_c, d_c = src - mu_s, dst - mu_d
    if fixed_r is None:
        cov = d_c.T @ s_c / len(src)
        u, d, vt = np.linalg.svd(cov)
        rot = u @ vt
        if np.linalg.det(rot) < 0:
            u[:, -1] *= -1
            rot = u @ vt
        scale = float(np.trace(np.diag(d)) / ((s_c ** 2).sum() / len(src)))
    else:
        rot = fixed_r
        scale = float((d_c * (s_c @ rot.T)).sum() / (s_c ** 2).sum())
    trans = mu_d - scale * rot @ mu_s
    return scale, rot, trans


def load_room_objects(scene_uuid: str, room: str) -> dict[str, tuple[trimesh.Trimesh, str]]:
    """Load furniture nodes of ``<room>_full.glb`` as ``node_name -> (mesh, model_uuid)``.

    Architecture / unnamed geometry (walls, floor, ceiling) carry no model UUID in
    the node name and are skipped, so only objects are returned.
    """
    full = os.path.join(SCENE_ROOT, scene_uuid, f"{room}_full.glb")
    if not os.path.exists(full):
        return {}
    scene = trimesh.load(full)
    nodes: dict[str, tuple[trimesh.Trimesh, str]] = {}
    for name in scene.graph.nodes_geometry:
        m = UUID_RE.search(name)
        if not m:
            continue
        transform, geom_name = scene.graph[name]
        geom = scene.geometry[geom_name].copy()
        geom.apply_transform(transform)
        nodes[name] = (geom, m.group(1))
    return nodes


def fit_similarity(ann: dict[str, Any],
                   nodes: dict[str, tuple[trimesh.Trimesh, str]],
                   thresh: float = 0.15) -> dict[str, Any] | None:
    """RANSAC estimate of the glb->annotation-world similarity transform.

    Each annotation object may match several same-model room nodes; we sample
    triples of (object, candidate-node) hypotheses, fit a similarity, and score it
    by the number of annotation objects whose nearest same-model node lands within
    ``thresh`` metres. Returns the transform plus the inlier node->object assignment.
    """
    ann_obj = [(o["model_file_name"][0], np.array(o["bbox3d_world_center"], float), oid)
               for oid, o in enumerate(ann["obj_dict"].values())]
    node_by_uuid: dict[str, list[tuple[str, np.ndarray]]] = {}
    for name, (geom, mid) in nodes.items():
        node_by_uuid.setdefault(mid, []).append((name, geom.bounds.mean(0)))
    cand = [[(nm, c) for nm, c in node_by_uuid.get(mid, [])] for mid, _, _ in ann_obj]
    have = [i for i, c in enumerate(cand) if c]
    if len(have) < 2:
        return None

    def score(scale: float, rot: np.ndarray, trans: np.ndarray
              ) -> tuple[list[float], dict[str, int]]:
        res: list[float] = []
        assign: dict[str, int] = {}
        for i in have:
            dst = ann_obj[i][1]
            nm, c = min(cand[i], key=lambda nc: np.linalg.norm(scale * (rot @ nc[1]) + trans - dst))
            d = float(np.linalg.norm(scale * (rot @ c) + trans - dst))
            if d < thresh:
                res.append(d)
                assign[nm] = ann_obj[i][2]
        return res, assign

    best: tuple[tuple[int, float], float, np.ndarray, np.ndarray, list[float], dict[str, int]] | None = None
    if len(have) >= 3:
        trip = sorted(have, key=lambda i: len(cand[i]))[:min(len(have), 6)]
        for combo in combinations(trip, 3):
            for picks in product(*[cand[i] for i in combo]):
                src = np.array([p[1] for p in picks])
                dst = np.array([ann_obj[i][1] for i in combo])
                if not (np.isfinite(src).all() and np.isfinite(dst).all()):
                    continue
                try:
                    scale, rot, trans = umeyama(src, dst)
                except np.linalg.LinAlgError:
                    continue
                res, assign = score(scale, rot, trans)
                key = (len(res), -float(np.sum(res)) if res else 0.0)
                if best is None or key > best[0]:
                    best = (key, scale, rot, trans, res, assign)
    if best is None:  # two-object scene: fix the canonical rotation
        src = np.array([cand[i][0][1] for i in have])
        dst = np.array([ann_obj[i][1] for i in have])
        gm = np.isfinite(src).all(1) & np.isfinite(dst).all(1)
        if gm.sum() < 2:
            return None
        try:
            scale, rot, trans = umeyama(src[gm], dst[gm], CANONICAL_R)
        except np.linalg.LinAlgError:
            return None
        res, assign = score(scale, rot, trans)
        best = ((len(res), 0.0), scale, rot, trans, res, assign)
    _, scale, rot, trans, res, assign = best
    if not res:
        return None
    return dict(scale=scale, rot=rot, trans=trans, n_inliers=len(res),
                max_res=float(np.max(res)), med_res=float(np.median(res)), assign=assign)


def camera_from_annotation(ann: dict[str, Any]) -> tuple[np.ndarray, np.ndarray]:
    """Return ``(K, T_cv_from_world)``: intrinsics and world->OpenCV-camera 4x4."""
    k = np.asarray(ann["camera_intrinsics"], float)
    w2c = np.eye(4)
    w2c[:3] = np.asarray(ann["camera_extrinsics"], float)          # world -> OpenGL cam
    rot, trans = w2c[:3, :3], w2c[:3, 3]
    t_world_from_cv = np.eye(4)
    t_world_from_cv[:3, :3] = rot.T @ CV2GL
    t_world_from_cv[:3, 3] = -rot.T @ trans
    return k, np.linalg.inv(t_world_from_cv)


def place_objects(nodes: dict[str, tuple[trimesh.Trimesh, str]], fit: dict[str, Any],
                  t_cv_from_world: np.ndarray
                  ) -> list[tuple[str, str, trimesh.Trimesh]]:
    """Transform each room object node glb->world (similarity)->OpenCV camera frame.

    Returns a deterministic list of ``(node_name, model_uuid, mesh_in_camera_frame)``.
    """
    scale, rot, trans = fit["scale"], fit["rot"], fit["trans"]
    placed: list[tuple[str, str, trimesh.Trimesh]] = []
    for name in sorted(nodes):
        geom, mid = nodes[name]
        mesh = geom.copy()
        mesh.vertices = scale * (rot @ mesh.vertices.T).T + trans     # -> world
        mesh.apply_transform(t_cv_from_world)                          # -> camera (cv)
        placed.append((name, mid, mesh))
    return placed


def raycast_instance_mask(placed: list[tuple[str, str, trimesh.Trimesh]],
                          k: np.ndarray, hw: tuple[int, int], stride: int = 1
                          ) -> tuple[np.ndarray, np.ndarray]:
    """Ray-cast placed objects through ``K``; return ``(instance_id_map, z_depth)``.

    Instance ids are ``1..len(placed)`` (0 = background); the nearest surface wins
    per pixel. ``z_depth`` is the camera-frame z of the hit (inf where no hit).
    """
    height, width = hw
    faces_obj = np.concatenate([np.full(len(m.faces), i + 1, np.int32)
                                for i, (_, _, m) in enumerate(placed)])
    combined = trimesh.util.concatenate([m for _, _, m in placed])
    fx, fy, cx, cy = k[0, 0], k[1, 1], k[0, 2], k[1, 2]
    us, vs = np.meshgrid(np.arange(0, width, stride), np.arange(0, height, stride))
    flat_u, flat_v = us.ravel(), vs.ravel()
    dirs = np.stack([(flat_u - cx) / fx, (flat_v - cy) / fy, np.ones_like(flat_u, float)], -1)
    dirs /= np.linalg.norm(dirs, axis=1, keepdims=True)
    origins = np.zeros_like(dirs)
    loc, ray_idx, tri_idx = combined.ray.intersects_location(origins, dirs, multiple_hits=False)
    id_flat = np.zeros(flat_u.shape, np.int32)
    z_flat = np.full(flat_u.shape, np.inf)
    for r, tri, xyz in zip(ray_idx, tri_idx, loc):
        if xyz[2] < z_flat[r]:
            z_flat[r] = xyz[2]
            id_flat[r] = faces_obj[tri]
    out_h, out_w = us.shape
    return id_flat.reshape(out_h, out_w), z_flat.reshape(out_h, out_w)


def depth_agreement(z_render: np.ndarray, depth: np.ndarray) -> dict[str, float]:
    """Agreement between rendered object z and dataset metric depth on covered pixels."""
    valid = np.isfinite(z_render) & np.isfinite(depth) & (depth > 0) & (depth < 100)
    if valid.sum() == 0:
        return dict(coverage=0.0, med_mm=float("inf"), within5mm=0.0, n=0)
    err = np.abs(z_render[valid] - depth[valid])
    return dict(coverage=float(np.isfinite(z_render).mean()),
                med_mm=float(np.median(err) * 1000), within5mm=float((err < 0.005).mean()),
                n=int(valid.sum()))


def shortlist_rooms(ann: dict[str, Any], u2rooms: dict[str, set[str]]) -> list[str]:
    """Rooms whose model set covers all annotation models (else the best-covering ones)."""
    uuids = set(o["model_file_name"][0] for o in ann["obj_dict"].values())
    sets = [u2rooms.get(u, set()) for u in uuids]
    if sets and all(sets):
        common = set.intersection(*sets)
        if common:
            return sorted(common)
    from collections import Counter
    counter: Counter[str] = Counter()
    for s in sets:
        counter.update(s)
    if not counter:
        return []
    top = max(counter.values())
    return sorted(r for r, n in counter.items() if n == top)


def process_scene(scene_id: str, u2rooms: dict[str, set[str]], out_root: str,
                  top_k: int, sel_stride: int, min_conf: float = 0.5) -> dict[str, Any]:
    """Match one scene to its 3D-FRONT room and, if confident, write GT into the
    scene folder next to the original files, using the ``_<index06>`` naming.

    Low-confidence matches (rendered depth disagrees with the metric depth) are
    not written; the scene is reported as ``low-confidence`` instead.
    """
    scene_dir = os.path.join(out_root, scene_id)
    idx6 = f"{int(scene_id):06d}"
    ann = json.load(open(glob.glob(f"{scene_dir}/annotation_*.json")[0]))
    k, t_cv_from_world = camera_from_annotation(ann)
    depth = np.load(glob.glob(f"{scene_dir}/depth_*.npy")[0]).astype(np.float64)
    height, width = depth.shape

    candidates = shortlist_rooms(ann, u2rooms)
    scored: list[tuple[tuple[int, float], str, str, dict[str, Any]]] = []
    for room_key in candidates:
        scene_uuid, room = room_key.split("|")
        nodes = load_room_objects(scene_uuid, room)
        if not nodes:
            continue
        fit = fit_similarity(ann, nodes)
        if fit is None:
            continue
        scored.append(((-fit["n_inliers"], fit["max_res"]), scene_uuid, room, fit))
    if not scored:
        return dict(scene=scene_id, status="no-match", n_candidates=len(candidates))
    scored.sort(key=lambda x: x[0])

    # verify the top-K by rendered-depth agreement (decisive for ambiguous scenes)
    best = None
    for _, scene_uuid, room, fit in scored[:top_k]:
        nodes = load_room_objects(scene_uuid, room)
        placed = place_objects(nodes, fit, t_cv_from_world)
        _, z_low = raycast_instance_mask(placed, k, (height, width), stride=sel_stride)
        agree = depth_agreement(z_low, depth[::sel_stride, ::sel_stride])
        key = (agree["within5mm"], -agree["med_mm"])
        if best is None or key > best[0]:
            best = (key, scene_uuid, room, fit, agree)
    _, scene_uuid, room, fit, _ = best

    # full-res render for the winner
    nodes = load_room_objects(scene_uuid, room)
    placed = place_objects(nodes, fit, t_cv_from_world)
    id_map, z_render = raycast_instance_mask(placed, k, (height, width), stride=1)
    agree = depth_agreement(z_render, depth)

    # id -> object metadata (computed before writing so we can gate on confidence)
    ann_by_oid = list(ann["obj_dict"].values())
    id_records: list[dict[str, Any]] = []
    for i, (name, mid, _) in enumerate(placed):
        inst = i + 1
        category = UUID_RE.split(name)[0].strip("_")
        oid = fit["assign"].get(name)
        label = ann_by_oid[oid]["label"][0] if oid is not None else category
        n_pix = int((id_map == inst).sum())
        id_records.append(dict(instance_id=inst, node_name=name, model_uuid=mid,
                               category=category, label=label, annotated=oid is not None,
                               obj_id=int(ann_by_oid[oid]["obj_id"][0]) if oid is not None else None,
                               n_pixels=n_pix, visible=n_pix > 0))

    confident = agree["within5mm"] >= min_conf
    result = dict(scene=scene_id, status="ok" if confident else "low-confidence",
                  scene_uuid=scene_uuid, room=room, confident=confident,
                  n_candidates=len(candidates), n_objects=len(placed),
                  n_annotated=sum(r["annotated"] for r in id_records),
                  fit=dict(scale=fit["scale"], n_inliers=fit["n_inliers"],
                           max_res=fit["max_res"], med_res=fit["med_res"]),
                  depth=agree, instances=id_records)
    if not confident:
        return result  # do not write GT for an unreliable match

    # write GT into the scene folder, matching the dataset's _<index06> convention
    obj_dir = os.path.join(scene_dir, f"objects_{idx6}")
    os.makedirs(obj_dir, exist_ok=True)
    Image.fromarray(id_map.astype(np.uint16)).save(os.path.join(scene_dir, f"instance_{idx6}.png"))
    merged: list[trimesh.Trimesh] = []
    for (name, _, mesh), rec in zip(placed, id_records):
        safe = re.sub(r"[^0-9a-zA-Z]+", "_", rec["label"]).strip("_")[:32]
        mesh.export(os.path.join(obj_dir, f"{rec['instance_id']:03d}_{safe}.ply"))
        merged.append(mesh)
    trimesh.util.concatenate(merged).export(os.path.join(scene_dir, f"sceneobjfull_{idx6}.ply"))
    save_overlay(scene_dir, id_map, os.path.join(scene_dir, f"instance_overlay_{idx6}.png"))
    json.dump({k2: v for k2, v in result.items() if k2 != "instances"} | {
        "similarity": dict(scale=fit["scale"], rot=fit["rot"].tolist(), trans=fit["trans"].tolist()),
        "instances": id_records}, open(os.path.join(scene_dir, f"instance_{idx6}.json"), "w"), indent=2)
    return result


def save_overlay(scene_dir: str, id_map: np.ndarray, path: str) -> None:
    """Blend the coloured instance mask over the rgb image for visual inspection."""
    rgb_path = (glob.glob(f"{scene_dir}/rgb_*.jpeg") + glob.glob(f"{scene_dir}/rgb_*.png"))[0]
    rgb = np.asarray(Image.open(rgb_path).convert("RGB"))
    if rgb.shape[:2] != id_map.shape:
        rgb = np.asarray(Image.fromarray(rgb).resize((id_map.shape[1], id_map.shape[0])))
    color = np.zeros_like(rgb)
    for inst in np.unique(id_map):
        if inst == 0:
            continue
        color[id_map == inst] = PALETTE[(inst - 1) % len(PALETTE)]
    fg = id_map > 0
    out = rgb.copy()
    out[fg] = (0.5 * rgb[fg] + 0.5 * color[fg]).astype(np.uint8)
    Image.fromarray(out).save(path)


def main() -> None:
    """CLI entry point: match and export GT for one or all single_image scenes."""
    ap = argparse.ArgumentParser(description=__doc__)
    ap.add_argument("--scenes", nargs="*", default=None, help="scene ids (default: all)")
    ap.add_argument("--index", default="/tmp/uuid_index.json",
                    help="model-uuid -> [[scene,room],...] index json")
    ap.add_argument("--out", default=SI_ROOT,
                    help="dataset root; GT is written into each <out>/<scene>/ folder")
    ap.add_argument("--top-k", type=int, default=8, help="candidates to depth-verify")
    ap.add_argument("--sel-stride", type=int, default=4, help="pixel stride for verification")
    args = ap.parse_args()

    idx = json.load(open(args.index))
    u2rooms = {u: set(f"{a}|{b}" for a, b in v) for u, v in idx.items()}
    scenes = args.scenes or [os.path.basename(p) for p in sorted(glob.glob(f"{args.out}/[0-9]*"))]

    summary = []
    for sid in scenes:
        try:
            res = process_scene(sid, u2rooms, args.out, args.top_k, args.sel_stride)
        except Exception as exc:  # noqa: BLE001 - keep the batch going
            res = dict(scene=sid, status=f"error:{type(exc).__name__}:{exc}")
        summary.append(res)
        if res["status"] in ("ok", "low-confidence"):
            d = res["depth"]
            flag = "" if res["confident"] else "  <-- LOW CONFIDENCE (skipped, likely wrong room)"
            print(f"{sid}: {res['scene_uuid'][:8]}/{res['room']:26} "
                  f"obj={res['n_objects']:2d} ann={res['n_annotated']} "
                  f"cover={d['coverage']*100:4.1f}% med={d['med_mm']:5.1f}mm "
                  f"<5mm={d['within5mm']*100:4.1f}%{flag}")
        else:
            print(f"{sid}: {res['status']}")
    json.dump(summary, open(os.path.join(args.out, "gt_3dfront_summary.json"), "w"), indent=2)


if __name__ == "__main__":
    main()