Renderable Neural Radiance Map for Visual Navigation
Obin KwonJeongho ParkSonghwai Oh
Proposes a 2D grid-based neural radiance map that embeds visual scene features into latent codes to enable real-time camera tracking, image-based localization, and image-goal movement across unseen environments without scene-specific retraining.
Autonomous visual navigation in unfamiliar indoor environments remains a significant challenge for robotics. Conventional approaches rely on simple geometric maps that lack rich visual information, while newer neural rendering methods are computationally intensive and require pre-training on specific target environments. This limits their practical deployment in real-time robotics where agents must quickly navigate unseen spaces under noisy real-world conditions.
The article introduces and evaluates the Renderable Neural Radiance Map, a novel grid-based spatial memory framework designed to capture 3D environmental appearance efficiently. The primary objective is to demonstrate that embedding visual latent codes into a 2D map enables real-time localization, novel view image synthesis, and robust image-goal navigation in unfamiliar environments without requiring per-scene optimization.
The authors designed a modular framework using a pre-trained encoder to convert color and depth camera images into latent vectors that are registered on a 2D grid, paired with a decoder capable of rendering 3D views. Evaluation was conducted through simulations using the Habitat platform across 72 indoor scenes from the Gibson dataset and standardized test paths. The system's performance was measured against leading reinforcement learning and modular baseline methods across camera tracking, image-based localization, and image-goal navigation tasks under sensor and movement noise.
The evaluation produced several key findings. First, the proposed framework achieved a 65.7% success rate in complex curved navigation scenarios, outperforming the existing state of the art by 18.6 percentage points. Second, the system operates with high computational efficiency, running mapping at 91.9 Hz and image localization at 56.8 Hz, while camera tracking operates at 5.0 Hz. Third, the localization framework achieved a 99% recall rate within a 50-centimeter error threshold in recorded maps and retained 97.4% accuracy even when one-third of the scene's objects changed. Finally, the framework demonstrated zero-shot generalization by successfully navigating and localizing in unseen environments without environment-specific fine-tuning.
These results demonstrate that structured spatial representations embedded with visual features provide a more sample-efficient and robust foundation for navigation than computationally demanding reinforcement learning policies. The high processing speeds and resilience to environmental alterations reduce operational risks and hardware overhead, making neural radiance concepts practical for real-time mobile robotics and automated facility inspections.
Organizations developing autonomous mobile systems should consider adopting grid-based neural radiance representations for vision-guided search and inspection tasks. Next steps should focus on deploying the framework onto physical robotic hardware to assess real-world sensor dynamics and developing graph-based optimization mechanisms to correct accumulated drift over extended operational timelines.
The findings are supported by comprehensive comparative simulations across standard industry benchmarks. However, confidence should be tempered by the fact that evaluations were conducted in simulated indoor environments with 3-degree-of-freedom movement. Additionally, the system faces limitations when correcting past mapping errors once features are registered, and performance degrades in environments with highly repetitive or visually ambiguous scenes.
- Paper: NeRF: Representing Scenes as Neural Radiance Fields for View Synthesis, Ben Mildenhall et al. (2020). This foundational paper establishes coordinate-based neural radiance fields and volume rendering for novel view synthesis, providing the core rendering concept that the source adapts into a 2D grid-based memory map.
- Paper: Habitat: A Platform for Embodied AI Research, Manolis Savva et al. (2019). This paper introduces the Habitat simulation platform and benchmark environments, which provide the primary evaluation framework and indoor scenes used to validate the source's navigation system.
- Paper: pixelNeRF: Neural Radiance Fields from One or Few Images, Alex Yu et al. (2021). This work formulates generalizable neural radiance fields from sparse image inputs via pixel-aligned visual features, directly informing the source's pre-trained encoder-decoder approach for zero-shot view synthesis.
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- Paper: Direct Voxel Grid Optimization: Super-fast Convergence for Radiance Fields Reconstruction, Cheng Sun et al. (2021). This paper demonstrates explicit voxel grid optimization for rapid radiance field convergence, providing foundational concepts for accelerating neural scene representation without slow MLP per-scene optimization.
- Paper: Scene Representation Networks: Continuous 3D-Structure-Aware Neural Scene Representations, V. Sitzmann et al. (2019). This work introduces continuous 3D structure-aware neural scene representations learned directly from 2D images, laying theoretical groundwork for rendering 3D views from latent scene features.
- Paper: GOAT-Bench: A Benchmark for Multi-Modal Lifelong Navigation, Mukul Khanna et al. (2024). This benchmark extends visual navigation from single-goal episodes into lifelong multimodal navigation, evaluating whether spatial memory systems can continually adapt over extended sequential tasks.
- Paper: Reloc3r: Large-Scale Training of Relative Camera Pose Regression for Generalizable, Fast, and Accurate Visual Localization, Siyan Dong et al. (2025). This work scales relative camera pose regression for fast zero-shot visual localization across diverse scenes, building on the real-time visual localization requirements explored in the source.
- Paper: OpenNeRF: Open Set 3D Neural Scene Segmentation with Pixel-Wise Features and Rendered Novel Views, Francis Engelmann et al. (2024). This paper extends neural radiance fields with pixel-aligned vision-language embeddings and novel view synthesis for open-set 3D semantic understanding in indoor environments.
- Paper: Feature 3DGS: Supercharging 3D Gaussian Splatting to Enable Distilled Feature Fields, Shijie Zhou et al. (2024). This paper integrates distilled 2D foundation model features into explicit 3D radiance fields, advancing real-time scene rendering to include downstream semantic segmentation and editing.
- Paper: SPOC: Imitating Shortest Paths in Simulation Enables Effective Navigation and Manipulation in the Real World, Kiana Ehsani et al. (2024). This work builds upon simulated visual navigation by leveraging large-scale procedural environments and shortest-path cloning to enable robust real-world robotic navigation and manipulation.
