A BENCHMARK FOR ACTIVE 3D SPATIAL REASONING

SpatialScout.

Can VLM agents actively
explore and map 3D scenes?

Move the camera. Connect the views. Locate objects in 3D.
An interactive benchmark where observation is part of the reasoning.

RGB observations·Camera tools·Geometric reasoning
+ THE WORLD IS YOUR NEXT OBSERVATION
SpatialScout overview: cameras explore an apartment and triangulate object positions
01 / ACTIVE EXPLORATIONObserve → Explore → Locate

Zhaoxi Zhang · Hao Liang · Linxuan Wu · Yiming Wu · Yifu Yuan · Kun Liang · Chenming Tang · Meiyi Qiang · Wentao Zhang · Weikang Li

Cite this work ↗
80indoor scenes
3,140target objects
5scene sources
8model configurations
100turns per task
01 / THE BENCHMARK

A scene to explore.
A map to build.

A VLM controls a virtual camera, chooses new viewpoints, and predicts the geometric centers of target objects in the initial camera frame.

Diverse spaces. One protocol.

80 scenes
x → forward   y → left   z → upInitial camera frame · meters

From views to coordinates

VIEW AVIEW Bxyz_m

Capture RGB views and read camera poses.

Schematic illustration
Input RGB images + entity library→Actions Camera + geometry tools→Output Object centers in 3D
02 / THE RESULTS

Seeing more is only
part of the challenge.

Compare eight model configurations on localization and coverage. Switch the evaluation scope to explore all targets or only the submitted objects.

ModelTasks

Task-average (macro) metrics. Missing targets count as zero for “All objects.” Thresholds are strict. Only trajectories ending with successful finish_mapping are included; task counts differ by configuration.

Three ways a reconstruction can turn out

Three reconstruction examples comparing ground truth and model output from multiple viewpoints

Ground truth and reconstruction from three viewpoints reveal geometric accuracy, missing objects, and localization failures.

03 / THE TRADE-OFF

Mapping accuracy.
Measured against cost.

Price and performance span orders of magnitude. Explore the configurations that improve reconstruction quality for a given average task cost.

Highest reconstruction IoU41.71%Claude Opus 5.5 · all-object micro IoU
Astra, medium$2.47Average per task · 52 recorded tasks
Lowest recorded mean cost$0.027DeepSeek V4.1 Flash · per task
Pareto frontier

Hover or focus on a model to see its exact cost and measurement count.

How the cost comparison is measured +

Costs use the saved OpenRouter pricing snapshot (19 October 2026), including input, output and recorded cache usage. The mean uses only tasks with complete token records; coverage differs across models. Astra medium combines its previous IoU score with the newer run’s recorded task costs.

This chart uses object-average (micro) IoU, matching the existing cost figure. The result table above uses task-average (macro) metrics. Dollar amounts are estimates under the saved pricing, not billing receipts.

Open the original cost figure ↗ Download the data snapshot ↓
04 / REPRODUCE

Your model.
The same scenes.

Source code, fixed task definitions, and scene resources are available. Use your own vision-and-tool-capable model endpoint to rerun the 80-task protocol.

● ● ●Run the benchmark
# From the repository root, after installation
export VLM_BASE_URL='https://YOUR_API_HOST/v1'
export VLM_API_KEY='YOUR_MODEL_API_KEY'
export VLM_MODEL='EXACT_MODEL_ID'
export EVAL_OUTPUT_DIR=outputs/room_benchmark/my_model

bash scripts/run_evaluation.sh

# Compute the eight IoU metrics
.venv/bin/python -m spatialscout.evaluation.score \
  "$EVAL_OUTPUT_DIR"
CITATION

Build on SpatialScout.

If you use this benchmark in your research, please cite our paper.

Download BibTeX ↓