Research map / 3D vision / Gaussian splatting
FlexDrive: Toward Trajectory Flexibility in Driving Scene Gaussian Splatting Reconstruction and Rendering
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Proposes FlexDrive, which uses Inverse View Warping with a Depth Bootstrap strategy to supervise out-of-path viewpoints in 3DGS driving-scene reconstruction, and introduces a CARLA-based out-of-path benchmark.
Problem
Driving scene Gaussian splatting reconstructions render well along pre-recorded vehicle paths but degrade for out-of-path viewpoints because no ground-truth images exist for those views.
Approach
Inverse View Warping renders the in-path image at a sampled out-of-path viewpoint using occlusion-aware rasterization and then rearranges pixels back to the in-path layout, so the real in-path image serves as supervision; dense depth for lifting pixels comes from a Depth Bootstrap that rectifies rendered depth with LiDAR via a linear fit.
Key results
- On the CARLA-based out-of-path benchmark, FlexDrive reaches 26.23 PSNR and 0.372 LPIPS versus 24.84 PSNR for LidaRF and 21.65 for PVG.
- On Waymo in-path rendering, FlexDrive gets 31.25 PSNR on static and 30.76 on dynamic scenes, comparable to StreetGaussian (31.35 / 30.73).
- Ablation on LidaRF-GS baseline: adding DB and IVW raises CARLA out-of-path PSNR from 24.79 to 26.23.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| Add DB and IVW to LidaRF-GS (ablation) | LidaRF-GS · CARLA out-of-path | PSNR: 24.79 -> 26.23 | Helped |
| Add depth bootstrapping (DB) (ablation) | LidaRF-GS · CARLA out-of-path | PSNR: 24.79 -> 25.57 | Helped |
| Add inverse view warping (IVW) (ablation) | LidaRF-GS · CARLA out-of-path | PSNR: 24.79 -> 25.71 | Helped |
| Use DB with IVW rather than IVW alone (ablation) | LidaRF-GS · CARLA out-of-path | PSNR: 25.71 -> 26.23 | Helped |
| Set occlusion threshold β to 0.8 instead of 0.95 (ablation) | FlexDrive · single scene | PSNR: 32.23 -> 30.90 | Hurt |
| Set occlusion threshold β to 0.5 instead of 0.95 (ablation) | FlexDrive · single scene | PSNR: 32.23 -> 29.65 | Hurt |
| Disable occlusion handling with β = 0 (ablation) | FlexDrive · single scene | PSNR: 32.23 -> 20.12 | Hurt |
| Use FlexDrive instead of NeuraD | driving scene reconstruction · CARLA out-of-path | PSNR: 25.10 -> 26.23 | Helped |
Surprising findings
- Without occlusion-aware rasterization (beta=0), single-scene PSNR collapses to 20.12 versus 32.23 at beta=0.95, showing occlusion handling is critical.
Limitations
- Out-of-path evaluation on Waymo relies on FID, which the authors note is an unreliable quality indicator.
- Out-of-path benchmark is built on the CARLA simulator rather than real driving data.
- Method is restricted to views near the recorded trajectory; completely free camera movement is left to future work.
Experimental setup
Datasets: Waymo Open Dataset CARLA simulator data
Benchmarks: Waymo Open Dataset CARLA-based out-of-path benchmark
Metrics: PSNR SSIM LPIPS FID
Baselines: 3D GS PVG EmerNeRF LidaRF NeuraD StreetGaussian LidaRF-GS
Builds on: 3D Gaussian Splatting LidaRF PVG StreetGaussian
Closest papers by meaning
- DrivingForward: Feed-forward 3D Gaussian Splatting for Driving Scene Reconstruction from Flexible Surround-view Input (AAAI 2025 · similarity 0.89)
- SplatAD: Real-Time Lidar and Camera Rendering with 3D Gaussian Splatting for Autonomous Driving (CVPR 2025 · similarity 0.89)
- DrivingGaussian: Composite Gaussian Splatting for Surrounding Dynamic Autonomous Driving Scenes (CVPR 2024 · similarity 0.88)
- EGSRAL:An Enhanced 3D Gaussian Splatting Based Renderer with Automated Labeling for Large-Scale Driving Scene (AAAI 2025 · similarity 0.88)
- Swift4D: Adaptive divide-and-conquer Gaussian Splatting for compact and efficient reconstruction of dynamic scene (ICLR 2025 · similarity 0.87)
- Speedy-Splat: Fast 3D Gaussian Splatting with Sparse Pixels and Sparse Primitives (CVPR 2025 · similarity 0.87)
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