Stage 1 · SUSP Scene Scanning
Scene Point-Cloud Collection and Semantic Fusion
Build a scene-level geometric backbone aligned with RGB, segmentation, LiDAR, and pose data.
Stage 1 starts from the simulator scene itself together with the runtime configuration
that defines sensor settings, sampling bounds, altitude, and pose coverage. The goal is
not to generate benchmark questions directly, but to reconstruct a
stable scene-level geometric backbone that later stages can mine
repeatedly without returning to image space.
In the current implementation, this stage follows the same logic described in the paper:
multi-pose sampling, raw chunk capture, and global semantic fusion. RGB, segmentation,
LiDAR, and pose metadata are captured at every sampled pose, then transformed into a
unified scene coordinate system so that semantic and instance identities remain attached
to the fused point cloud. The result is a scene-scale representation that Stage 2 can
split directly into landmark candidates rather than re-detecting objects from scratch.
The key output of Stage 1 is therefore not a benchmark row but a
geometric substrate. By the time this stage finishes, every released
scene already has a stable map boundary, fused point cloud, global coordinate system, and
scan preview record. That shared spatial backbone is what lets later
stages reason about landmark visibility, relative position, orbit feasibility, and scene
coverage without repeatedly solving low-level mapping problems.
Inputs
Scene configs define MapBound, altitude, yaw sweep, and runtime capture
parameters; each sampled pose records synchronized RGB, segmentation, LiDAR, and pose
metadata.
Core Transform
Raw chunks are fused into a scene-scale semantic point cloud while preserving
semantic and instance identities, so Stage 2 can aggregate landmark candidates
directly from geometry-aware assets.
Outputs
The released handoff is a set of scene-scale assets such as fused point-cloud files,
scan preview media, and scene metadata that keep Stage 1 coverage auditable before
landmark mining begins.
Reproduce
python scripts/flightmvstg/stage1_collect_pcd.py --config configs/flightmvstg/task_airsim_env_7.yaml --mode all --scene-id env_7 --engine airsim
The scene scanning library below exposes benchmark-facing panoramas for the released test
scenes while keeping Stage 1 metadata visible. Each entry now combines two released RGB
scene snapshots with two segmented point-cloud panoramas rendered in top-down and oblique
views, together with the configured scene boundary, mapped area, and the complete
unscreened landmark-candidate count that Stage 2 begins from.
Scene Scanning Library. Two benchmark-facing RGB scene snapshots and
two segmented point-cloud panoramas are shown for each released test environment together
with Stage 1 boundary metadata and the unscreened Stage 2 candidate pool.
Stage 2 · SUSP Landmark Extraction
Landmark Review and Semantic Annotation
Turn the fused scene cloud into a reviewed, semantically named landmark pool.
Stage 2 consumes the fused semantic and instance-aware cloud from Stage 1 and converts it
into reviewed landmark assets. The pipeline first groups points by
semantic class and instance identity, then renders multiview RGB and point-cloud
evidence around each candidate so that geometric structure, appearance, and view
direction are all available before any benchmark task is built.
For each landmark candidate, the pipeline computes eight orbit-view capture
poses from the 3D bounding box and instance center, covering
the canonical directions front, front-right, right, back-right, back, back-left,
left, and front-left. The associated segmented point-cloud views are then used to
perform occlusion-aware validity checks, so heavily blocked or
non-informative directions can be excluded before benchmark-facing landmark assets are
finalized.
This is the stage where scene geometry becomes benchmark object assets.
Review removes unstable or uninformative candidates, confirms the main view, and finalizes
the reviewed landmark manifest used by both Stage 3 and Stage 4. After
review, the pipeline runs a constrained auto-label prompt to add coarse
category, fine-grained subcategory, and a short discriminative description that later
prompts can reuse.
The important shift is that Stage 2 turns a fused but still machine-oriented scene map
into benchmark-facing semantic objects. Candidate aggregation, multiview
review, and prompt-constrained annotation are linked in one chain: only after geometry,
visibility, and main-view consistency are confirmed does the pipeline allow a landmark to
receive the semantic fields that later prompt templates depend on.
Step 1 · Candidate Aggregation. The pipeline first partitions the fused
semantic cloud by semantic class and instance identity. Each resulting candidate is then
packaged with multiview RGB evidence, point-cloud views, 3D center metadata, and 3D box
support so that later review decisions are made against geometry-aware evidence rather
than isolated screenshots. At this stage the pool is intentionally permissive: the goal
is to surface all plausible landmark candidates before benchmark-facing filtering begins.
Step 2 · Review and Main-View Confirmation. Human review then removes
unstable or uninformative instances, confirms the most representative main view, verifies
one landmark-centric direction anchor, and checks bbox validity. The main view is not
required to be the front image; it is simply the clearest and most
benchmark-facing reference view. Once that anchor direction is confirmed, the remaining
seven directions are derived automatically in the fixed orbit order rather than being
edited independently. At this step, reviewers also manually remove unusable view
images that remain visually ambiguous, severely occluded, or otherwise unsuitable
even after the earlier geometric filtering. Candidates can be dropped immediately, but a
landmark is only kept after the main-view and direction checks are complete. The accepted
pool is frozen in the reviewed landmark manifest (valid_instances.json),
which becomes the only stable Stage 2 handoff consumed by both later stages. In practice
this step turns a broad candidate inventory into a controlled landmark repository whose
direction labels, representative views, and spatial references can be trusted downstream.
Step 3 · Prompt-Constrained Semantic Annotation. After geometric review,
the pipeline runs a constrained auto-label prompt to enrich each landmark with benchmark-
facing semantics. This is not free-form captioning: the prompt explicitly constrains
category choices, subtype naming, and JSON formatting so that landmark semantics remain
short, discriminative, and machine-parseable. The result is a semantic layer that later
prompt templates can reuse directly without re-describing each landmark from scratch.
In practice, Stage 2 Step 2-4 are completed in the local review workspace.
That interface is where reviewers perform candidate screening, main-view confirmation,
single-direction anchoring, invalid-view cleanup, auto-label launch, and final semantic
audit. The command line remains useful for collection and standalone auto-label reruns,
but the web is the recommended working surface whenever view quality and semantic
correctness need to be judged together from visual evidence.
Layer 1 · Coarse Category. A closed eight-class ontology anchors every landmark before later task generation.
The prompt must choose exactly one coarse category from the fixed benchmark-facing list: building, vehicle, public_facility, urban_landscape, transport_infrastructure, industrial_infrastructure, vegetation, or other.
Layer 2 · Fine-Grained Subcategory. The second layer stays flexible but must remain category-consistent and generic.
Subcategories cannot be proper nouns or brands; they act as reusable landmark types such as mid-rise building, trash bin, shipping container stack, or deciduous tree.
Layer 3 · Discriminative Description. A short noun phrase captures the identifying cues that later prompts can reuse.
Descriptions must stay under twenty words while preserving subtype, color, shape or texture, and any local visual cue that helps distinguish nearby landmarks.
The reviewed landmark scanning library below makes that Stage 2 handoff concrete: it shows
each retained landmark view together with the paired segmented point-cloud
rendering captured from the same scanning pose. This is the evidence basis from
which later prompt templates, mission planners, and image-task constructors all reuse
Stage 2 landmark assets after review and semantic labeling are finalized.
Landmark Scanning Library. Reviewed landmark-centric RGB side views are
shown together with their corresponding segmented point-cloud views, preserving the
scan-level evidence that underlies later image and video task construction.
Auto-Label Prompt Package
System Prompt
You are an aerial landmark recognition expert. Only use image evidence.
Output Schema
{"category":"building|vehicle|public_facility|urban_landscape|transport_infrastructure|industrial_infrastructure|vegetation|other","subcategory":"...","description":"...","confidence":0.0}
User Prompt Template
- class_name: {class_name or '(empty)'} (user-filled weak hint from Step 2, optional)
- images: up to 4 views (front/back/left/right preferred, some directions may be missing)
- Each uploaded image has a red bounding box marking the landmark, and the side label (e.g., 'Visible Side: Front (Landmark-centric)') at the top-left corner shows the visible side of the landmark in the object-centric (landmark-centric) frame.
category candidates (must choose from list):
[building, vehicle, public_facility, urban_landscape,transport_infrastructure, industrial_infrastructure, vegetation, other]
subcategory requirements:
- flexible generic subtype, not a proper noun or brand name
- must stay category-consistent
- examples below are illustrative only; use other common descriptive terms or phrases if they better match the landmark
• building: low-rise building, mid-rise building, high-rise building, warehouse, pagoda, chapel, factory shed, rural farmhouse, glass skyscraper, brick schoolhouse
• vehicle: sedan car, delivery van, city bus, cargo truck, motorcycle, construction excavator
• public_facility: street lamp post, bus shelter, public bench, trash bin, fire hydrant, antenna
• urban_landscape: sculpture, plaza, fountain, city square, urban garden, landscape installation, signboard, billboard, advertising board, wayfinding sign, landmark signage
• transport_infrastructure: arch bridge, overpass, railway track, tunnel entrance, roundabout, pedestrian crosswalk, subway station entrance, traffic island, railway platform
• industrial_infrastructure: shipping container stack, oil storage tank, grain silo, crane tower, pipeline
• vegetation: deciduous tree, coniferous tree, palm tree, shrub cluster, hedge row, grassy lawn
• other: temporary tent, rubble pile, playground slide, inflatable archway, construction barrier
description constraints (`description`):
- one noun phrase, <= 20 words
- must include: subcategory, color, shape/texture
- may include surrounding relation, visible text/pattern cues to distinguish the landmark
- positive examples:
- dark red middle-rise building with white neon light featuring the word "HOTEL" on the top
- gray pagoda-like tower with layered roof edges beside roadside trees
- white arch bridge with curved span above a narrow river channel
- dark stone obelisk with sharp top in open paved square
Output JSON (no extra explanation text):
{
"category": "building|vehicle|public_facility|urban_landscape|transport_infrastructure|industrial_infrastructure|vegetation|other",
"subcategory": "...",
"description": "...",
"confidence": 0.0
}
Outputs and Bridge
The released Stage 2 outputs live in the raw and reviewed landmark bundles; reviewed
RGB views, main-view tags, semantic layers, and short descriptions then become the
common substrate reused by Stage 3 and Stage 4.
Reproduce
python scripts/flightmvstg/stage2_landmark_label.py --config configs/flightmvstg/task_airsim_env_7.yaml --scene-id env_7 --mode review_instances_web --port 20261