I2O2I-Nav: A Benchmark with a Modular Agent for Long-Horizon Indoor-to-Outdoor-to-Indoor Navigation
Organizations: University of Hong Kong · Shanghai Jiao Tong University · Independent Researcher · NeoWa Robotics ·
Abstract
Service and delivery robots often need to complete long-horizon navigation missions spanning indoor and outdoor environments. Existing embodied navigation benchmarks primarily evaluate isolated stages or partial cross-domain journeys, providing limited support for assessing how heterogeneous navigation capabilities compose under continuous execution. We introduce I2O2I-Nav, a physics-enabled benchmark of 20 real-world composite scenes spanning over 115,000 square meters across multiple buildings and floors, with aligned 3DGS rendering and collision geometry. Its three-level evaluation progresses from independent primitives to two-stage compositions and complete four-stage I2O2I missions. Each stage starts from its predecessor's actual endpoint, while stage-conditional metrics track completion and localize failures along the mission. We further propose the MODULAR-Agent that coordinates frozen navigation policies through completion verification, stage handoffs, and bounded recovery. Evaluation across 1,374 episodes highlights the difficulty of continuous composition. The MODULAR-Agent achieves 40.5-76% success on individual primitives, but full I2O2I success remains low. Compared with a fixed policy chain using the same underlying policies, it more than doubles success on both Indoor-to-Outdoor (I2O) and Outdoor-to-Indoor (O2I), while improving full-mission success from 1.15% to 4.02%. Stage-wise analysis shows that the MODULAR-Agent enables more missions to reach the final object-navigation stage, where conditional success remains low, revealing challenges in both long-horizon stage execution and completion decisions.
Figures & tables
| Benchmark | Domain | Cross-floor | 3DGS | Simulator | Robot dynamics | Task dims |
|---|---|---|---|---|---|---|
| R2R | Indoor | Matterport3D Simulator | 1 | |||
| RxR | Indoor | Matterport3D Simulator | 1 | |||
| VLN-CE | Indoor | Habitat | 1 | |||
| VLN-PE | Indoor | GRUtopia / Isaac Sim | 1 | |||
| HM3D-OVON | Indoor | Habitat | 1 | |||
| BridgeNav | Outdoor | / | Generated-video evaluation | 2 |
| Exit | Entrance | OVON | OutdoorNav | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Method | SR | SPL | TL | SR | SPL | TL | SR | SPL | TL | Method | SR | SPL | DCR |
| Uni-NaVid | 0.00 | 0.00 | 1.14 | 0.00 | 0.00 | 1.49 | 7.00 | 7.00 | 0.59 | OmniNav-fast | 70.00 | 66.15 | 54.50 |
| OmniNav | 29.00 | 18.29 | 156.11 | 14.50 | 10.26 | 35.53 | 38.00 | 35.73 | 21.19 | SocialNav | 74.00 | 70.23 | 79.39 |
| LightNav-0 | 20.50 | 12.56 | 11.22 | 12.50 | 10.91 | 15.43 | 18.50 | 15.60 | 15.08 | MODULAR-Agent (O) | 74.00 | 69.32 | 55.35 |
| MODULAR-Agent (O) | 45.50 | 29.56 | 74.54 | 51.00 | 30.78 | 48.02 | 40.50 | 32.26 | 46.28 | MODULAR-Agent (S) | 76.00 | 70.60 | 80.06 |
| I2O: Exit OutdoorNav | O2I: OutdoorNav Entrance | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Configuration | FSR | CSR | SPL | RC | DCR | FSR | CSR | SPL | RC | DCR | ||||
| OmniNav + SocialNav | 14.00 | 17.25 | 11.90 | 28.50 | 42.24 | 20.50 | 68.29 | 12.50 | 42.75 | 8.78 | 82.93 | 53.39 | 73.00 | 17.12 |
| MODULAR-Agent (O + S) | 30.50 | 36.50 | 23.41 | 51.32 | 57.96 | 42.50 | 71.76 | 32.50 | 52.00 | 22.27 | 82.43 | 51.92 | 71.50 | 45.45 |
| Full mission | Stage-conditional success | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Configuration | FSR | CSR | SPL | RC | DCR | ||||
| OmniNav + SocialNav | 1.15 | 14.22 | 0.90 | 35.62 | 43.81 | 29.89 | 67.31 | 28.57 | 20.00 |
| MODULAR-Agent (O + S) | 4.02 | 26.15 | 1.08 | 47.79 | 56.05 | 45.40 | 79.75 | 52.38 | 21.21 |
Appendix figures & tables13 assets
Supplementary material from the paper’s appendix.
Appendix
| Scene | Area (m 2 ) | Object goals | Environment type |
|---|---|---|---|
| Scene 1 | 17,027.6 | 8 | School |
| Scene 2 | 5,350.7 | 8 | School |
| Scene 3 | 4,565.1 | 13 | School |
| Scene 4 | 4,508.1 | 10 | School |
| Scene 5 | 4,566.8 | 6 | School |
| Scene 6 | 5,080.6 | 15 | School |
| Level | L1 | L2 | L3 | All | ||||
|---|---|---|---|---|---|---|---|---|
| Task | Exit | OutdoorNav | Entrance | OVON | I2O | O2I | I2O2I | Total |
| Episodes | 200 | 200 | 200 | 200 | 200 | 200 | 174 | 1,374 |
| Policy | Registry entry and aliases | Stages | Role |
|---|---|---|---|
| OmniNav | omninav (omninav_3view) | exit, entrance, ovon | default executor for Exit, Entrance, OVON |
| OmniNav-fast | omninav_fast (omninav-fast) | exit, entrance, outdoornav | outdoor executor in the (O) configuration |
| SocialNav | socialnav (social-nav) | outdoornav | outdoor executor in the (S) configuration |
| Uni-NaVid | uninavid (uni-navid) | exit, entrance, ovon | baseline policy |
| LightNav-0 | lightnav (lightnav0) | exit, entrance, ovon | baseline policy |
| Item | Setting |
|---|---|
| Model | kimi-k2.6 |
| Endpoint | /chat/completions under the configured base URL https://api.kimi.com/coding/v1 |
| Decoding | thinking disabled; max_tokens for location judgment, for planning and replanning, for verification; request timeout s |
| Images | Up to four RGB frames in fixed order: the step-start view, then the forward, left, and right views captured after the stop; JPEG with long edge |
| Messages | One system prompt and one user message per call, with prior events entering as rendered text |
| Parser fields | step_completed, step_confidence, step_reason, parent_completed, parent_confidence, parent_reason, evidence, retry_guidance |
| Budget | Value | Scope |
|---|---|---|
| Executed actions | episode | |
| Steps per attempt | attempt | |
| Wall clock | s | episode |
| Model requests | episode | |
| Verification cadence | every steps | stage |
| Periodic verifications | episode |