SEAR: Simple and Efficient Adaptation of Visual Geometric Transformers for Unpaired RGB+Thermal 3D Reconstruction
Organizations: Schindler EPFL Lab, Lausanne, Switzerland · EPFL, Lausanne, Switzerland · Örebro University, Örebro, Sweden
Abstract
Foundational feed-forward visual geometry models enable accurate and efficient camera pose estimation and scene reconstruction by learning strong scene priors from massive RGB datasets. However, their effectiveness drops when applied to mixed sensing modalities, such as RGB-thermal (RGB-T) images. We observe that while a visual geometry grounded transformer pretrained on RGB data generalizes well to thermal-only reconstruction, it struggles to align RGB and thermal modalities when processed jointly. To address this, we propose SEAR, a simple yet efficient fine-tuning strategy that adapts a pretrained geometry transformer to multimodal RGB-T inputs. Despite being trained on a relatively small RGB-T dataset, our approach significantly outperforms state-of-the-art methods for 3D reconstruction and camera pose estimation, achieving significant improvements over all metrics and delivering higher detail and consistency between modalities with negligible overhead in inference time compared to the original pretrained model. Notably, SEAR enables reliable multimodal pose estimation and reconstruction even under challenging conditions, such as low lighting and dense smoke. We validate our architecture through extensive ablation studies and demonstrate how the model aligns both modalities. Additionally, we introduce a new dataset featuring RGB and thermal sequences captured at different times, viewpoints, and illumination conditions, providing a robust benchmark for future work in multimodal 3D scene reconstruction. Code and models are publicly available at https://doi.org/10.5281/ZENODO.21077295.
Figures & tables
| Public Datasets | SEAR Dataset | ||||||||||||
| Method | AUC | RRA | RTA | PCA | PCC | Chamfer | Reg (%) | FPS | AUC | RRA | RTA | Reg (%) | FPS |
| COLMAP +SPSG | 57.6 | 82.5 | 74.6 | 1.64 | 1.20 | 1.42 | 44.7 | 0.44 | 74.4 | 99.9 | 95.9 | 27.9 | 0.66 |
| 13.1 | 70.1 | 41.2 | 0.49 | 5.16 | 2.82 | 21.8 | 0.21 | 15.9 | 73.7 | 53.1 | 37.3 | 0.17 | |
| 41.0 | 68.3 | 63.0 | 0.97 | 1.09 | 1.03 | 98.7 | 0.05 | 48.2 | 65.9 | 68.9 | 100.0 | 0.04 | |
| MP-SfM | 31.4 | 78.0 | 52.5 | 1.59 | 0.58 | 1.08 | 100.0 | 0.04 | - | - | - | - | - |
| DUSt3R | 18.9 | 45.9 | 42.1 | 0.72 | 4.72 | 2.72 | 100.0 | 0.66 | 18.7 | 51.0 | 39.2 | 100.0 | 0.67 |
| Method | AUC@30 | RRA@30 | RTA@30 |
| No Camera Token | |||
| Thermal Projector | |||
| Thermal Embedding | |||
| Global Only | |||
| Frame Only | |||
| SEAR |
| No Camera Token | Thermal Projector | Thermal Embedding | Global Only | Frame Only | Ours | |
| No Camera Token | – | 0.72 | 0.91 | 0.12 | 1.00 | 0.24 |
| Thermal Projector | 0.28 | – | 0.83 | 0.04 | 1.00 | 0.05 |
| Thermal Embedding | 0.09 | 0.17 | – | 0.02 | 1.00 | 0.02 |
| Global Only | 0.88 | 0.96 | 0.98 | – | 1.00 | 0.78 |
| Frame Only | 0.00 | 0.00 | 0.00 | 0.00 | – | 0.00 |
| Ours | 0.76 | 0.95 | 0.98 | 0.22 | 1.00 | – |
Appendix figures & tables27 assets
Supplementary material from the paper’s appendix.
Appendix
| Dataset | #Training Scenes | #Evaluation Scenes | Aligned modalities | Cross positional | Cross temporal | Ground Truth |
| For training and quantitative evaluation | ||||||
| ThermoScenes | 17 | 5 | True | True | False | VGGT |
| ThermalGaussian | 11 | 3 | True | True | False | VGGT |
| ThermalMix | 4 | 2 | True | True | False | VGGT |
| ThermalNeRF | 7 | 2 | False | True | False | VGGT |
| RF | 9 | 6 | True | True | False | Motion Capture |
| prpt-cup | INR-building | |||||||||
| Method | AUC | RRA | RTA | Reg (%) | FPS | AUC | RRA | RTA | Reg (%) | FPS |
| COLMAP + SPSG | 49.4 | 73.7 | 75.3 | 51.2 | 0.40 | 34.9 | 52.3 | 57.6 | 49.7 | 0.49 |
| 16.3 | 70.0 | 45.0 | 4.0 | 0.18 | 2.6 | 61.6 | 13.6 | 15.6 | 0.19 | |
| 8.4 | 26.6 | 31.3 | 100.0 | 0.02 | 15.3 | 48.2 | 42.0 | 100.0 | 0.03 | |
| MP-SfM | 59.4 | 93.7 | 86.6 | 100.0 | 0.04 | 19.7 | 48.2 | 48.3 | 100.0 | 0.05 |
| DUSt3R | 19.9 | 29.2 | 32.9 | 100.0 | 0.43 | 6.5 | 44.6 | 33.9 | 100.0 | 0.66 |
| laptop | panel | |||||||||
| Method | AUC | RRA | RTA | Reg (%) | FPS | AUC | RRA | RTA | Reg (%) | FPS |
| COLMAP + SPSG | 56.6 | 100.0 | 90.9 | 10.8 | 0.28 | 17.6 | 32.2 | 48.3 | 28.0 | 0.32 |
| 23.2 | 51.1 | 61.5 | 48.9 | 0.15 | 46.0 | 73.6 | 98.1 | 35.4 | 0.36 | |
| 78.5 | 94.8 | 94.3 | 100.0 | 0.04 | 78.4 | 95.2 | 93.2 | 100.0 | 0.05 | |
| MP-SfM | 47.3 | 64.3 | 65.8 | 100.0 | 0.04 | 73.5 | 100.0 | 98.0 | 100.0 | 0.06 |
| DUSt3R | 21.1 | 44.1 | 46.1 | 100.0 | 0.67 | 15.5 | 70.4 | 39.4 | 100.0 | 0.65 |
| IronIngot | Parterre | |||||||||
| Method | AUC | RRA | RTA | Reg (%) | FPS | AUC | RRA | RTA | Reg (%) | FPS |
| COLMAP + SPSG | 96.0 | 100.0 | 99.7 | 100.0 | 0.54 | 46.0 | 100.0 | 100.0 | 3.0 | 0.53 |
| 13.7 | 56.0 | 58.5 | 61.5 | 0.12 | 32.0 | 66.8 | 85.5 | 24.2 | 0.23 | |
| 97.4 | 100.0 | 99.9 | 100.0 | 0.06 | 34.4 | 47.5 | 64.1 | 100.0 | 0.04 | |
| MP-SfM | 95.2 | 100.0 | 99.6 | 100.0 | 0.06 | 26.8 | 44.1 | 64.0 | 100.0 | 0.02 |
| DUSt3R | 15.5 | 75.0 | 39.6 | 100.0 | 0.66 | 43.1 | 95.3 | 79.5 | 100.0 | 0.65 |
| metallic-container | conference-room | |||||||||
| Method | AUC | RRA | RTA | Reg (%) | FPS | AUC | RRA | RTA | Reg (%) | FPS |
| COLMAP + SPSG | 75.8 | 100.0 | 96.8 | 61.5 | 0.59 | 78.1 | 99.6 | 94.0 | 25.4 | 0.84 |
| 14.1 | 97.8 | 43.2 | 50.0 | 0.17 | 2.4 | 56.0 | 9.0 | 15.2 | 0.34 | |
| 41.0 | 60.7 | 64.6 | 100.0 | 0.04 | 22.5 | 37.3 | 57.6 | 100.0 | 0.04 | |
| DUSt3R | 23.7 | 75.4 | 54.3 | 100.0 | 0.67 | 15.9 | 34.0 | 43.1 | 100.0 | 0.66 |
| MASt3R | 41.2 | 60.9 | 57.3 | 100.0 | 0.27 | 25.6 | 38.0 | 56.8 | 100.0 | 0.26 |
| 01_Annexet_No_Radars_0 | 01_Annexet_No_Radars_1 | |||||||||||||||
| Method | AUC | RRA | RTA | PCA | PCC | Chamfer | Reg (%) | FPS | AUC | RRA | RTA | PCA | PCC | Chamfer | Reg (%) | FPS |
| COLMAP + SPSG | 58.7 | 100.0 | 76.3 | 3.17 | 1.56 | 2.36 | 49.6 | 0.24 | 86.1 | 100.0 | 99.9 | 1.44 | 1.03 | 1.24 | 24.8 | 0.34 |
| 15.4 | 96.6 | 31.5 | 4.27 | 8.47 | 6.37 | 10.3 | 0.12 | 3.8 | 79.1 | 10.4 | 0.68 | 3.05 | 1.87 | 13.9 | 0.16 | |
| 65.8 | 100.0 | 87.3 | 0.60 | 0.57 | 0.59 | 95.9 | 0.06 | 22.7 | 49.1 | 56.6 | 1.95 | 4.84 | 3.39 | 100.0 | 0.05 | |
| MP-SfM | 7.4 | 89.2 | 26.0 | 1.2 | 0.5 | 0.8 | 100.0 | 0.03 | 2.0 | 70.2 | 14.9 | 5.0 | 1.4 | 3.2 | 100.0 | 0.03 |
| DUSt3R | 21.3 | 48.4 | 33.3 | 0.57 | 10.40 | 5.49 | 100.0 | 0.66 | 14.9 | 27.5 | 49.9 | 1.05 | 6.16 | 3.60 | 100.0 | 0.67 |
| Ebike | IronIngot | |||||||||
| Method | AUC | RRA | RTA | Reg (%) | FPS | AUC | RRA | RTA | Reg (%) | FPS |
| COLMAP + SPSG | 64.8 | 70.2 | 70.4 | 95.8 | 0.60 | 92.5 | 100.0 | 99.3 | 100.0 | 0.54 |
| 44.6 | 77.8 | 66.7 | 7.3 | 0.38 | 12.8 | 55.9 | 57.4 | 61.5 | 0.12 | |
| 93.9 | 100.0 | 100.0 | 100.0 | 0.07 | 94.2 | 100.0 | 99.6 | 100.0 | 0.06 | |
| MP-SfM | 93.6 | 100.0 | 99.8 | 100.0 | 0.06 | 94.1 | 100.0 | 99.3 | 100.0 | 0.06 |
| DUSt3R | 20.0 | 29.7 | 35.9 | 100.0 | 0.65 | 15.6 | 74.9 | 39.9 | 100.0 | 0.66 |
| sink | generator | |||||||||
| Method | AUC | RRA | RTA | Reg (%) | FPS | AUC | RRA | RTA | Reg (%) | FPS |
| COLMAP + SPSG | 86.4 | 100.0 | 98.5 | 38.2 | 0.61 | 52.7 | 79.8 | 73.8 | 100.0 | 0.64 |
| 12.4 | 87.2 | 35.0 | 37.3 | 0.24 | 4.2 | 53.1 | 27.0 | 19.7 | 0.22 | |
| 48.8 | 100.0 | 70.5 | 100.0 | 0.07 | 62.1 | 100.0 | 84.5 | 100.0 | 0.06 | |
| MP-SfM | 82.7 | 100.0 | 97.9 | 100.0 | 0.05 | 91.5 | 100.0 | 99.7 | 100.0 | 0.04 |
| DUSt3R | 33.6 | 100.0 | 61.6 | 100.0 | 0.67 | 7.4 | 41.4 | 32.9 | 100.0 | 0.66 |
| freezing_ice_cup | prpt-cup | |||||||||
| Method | AUC | RRA | RTA | Reg (%) | FPS | AUC | RRA | RTA | Reg (%) | FPS |
| COLMAP + SPSG | 34.5 | 57.2 | 60.5 | 50.0 | 0.52 | 51.4 | 72.0 | 75.3 | 48.1 | 0.61 |
| 1.5 | 30.6 | 22.3 | 7.6 | 0.33 | 20.2 | 70.0 | 40.0 | 2.6 | 0.27 | |
| 4.3 | 12.0 | 25.4 | 100.0 | 0.04 | 7.1 | 20.9 | 31.0 | 100.0 | 0.04 | |
| MP-SfM | 23.9 | 39.4 | 58.2 | 100.0 | 0.04 | 60.2 | 93.9 | 87.6 | 100.0 | 0.06 |
| DUSt3R | 14.6 | 30.1 | 42.4 | 100.0 | 0.66 | 19.9 | 28.2 | 33.6 | 100.0 | 0.65 |
| panel | laptop | |||||||||
| Method | AUC | RRA | RTA | Reg (%) | FPS | AUC | RRA | RTA | Reg (%) | FPS |
| COLMAP + SPSG | 15.8 | 31.8 | 46.4 | 28.0 | 0.32 | 56.1 | 100.0 | 91.6 | 10.8 | 0.28 |
| 43.7 | 76.4 | 98.6 | 35.4 | 0.36 | 20.6 | 51.0 | 56.4 | 48.9 | 0.15 | |
| 74.9 | 95.2 | 93.1 | 100.0 | 0.05 | 77.1 | 94.8 | 94.2 | 100.0 | 0.04 | |
| MP-SfM | 79.3 | 100.0 | 98.1 | 100.0 | 0.06 | 47.2 | 64.3 | 65.7 | 100.0 | 0.04 |
| DUSt3R | 15.9 | 70.4 | 39.5 | 100.0 | 0.65 | 21.1 | 44.0 | 45.9 | 100.0 | 0.67 |
| Method | AUC@5 | AUC@10 | AUC@20 | RRA@5 | RRA@10 | RRA@20 | RTA@5 | RTA@10 | RTA@20 |
| 0.3 | 1.0 | 4.5 | 7.1 | 17.8 | 37.3 | 3.0 | 8.1 | 23.6 | |
| 9.4 | 27.2 | 50.9 | 62.7 | 88.6 | 98.0 | 37.1 | 63.9 | 84.7 | |
| VGGT | 1.8 | 8.2 | 21.9 | 60.4 | 76.2 | 84.9 | 7.4 | 24.6 | 47.6 |
| SEAR | 23.6 | 47.3 | 68.0 | 92.3 | 97.5 | 98.1 | 57.7 | 81.9 | 92.8 |
| Method | AUC@30 | RRA@30 | RTA@30 | PCA | PCC | Chamfer |
| VGGT | 41.7 | 75.8 | 67.9 | 0.96 | 0.20 | 0.58 |
| SEAR | 71.8 | 93.7 | 90.8 | 0.49 | 0.07 | 0.28 |
| Method | AUC@30 | RRA@30 | RTA@30 | PCA | PCC | Chamfer | Reg., % | FPS |
| COLMAP + SPSG | 60.2 | 85.3 | 78.0 | 1.64 | 1.20 | 1.42 | 40.5 | 0.5 |
| 14.7 | 72.1 | 47.8 | 0.49 | 5.16 | 2.82 | 25.7 | 0.2 | |
| 42.6 | 67.7 | 64.3 | 0.97 | 1.09 | 1.03 | 99.0 | 0.0 | |
| DUSt3R | 18.9 | 47.0 | 41.4 | 0.72 | 4.72 | 2.72 | 100.0 | 0.7 |
| MASt3R | 32.7 | 66.4 | 55.9 | 0.66 | 0.27 | 0.46 | 100.0 | 0.2 |
| VGGT | 23.0 | 50.6 | 50.3 | 1.22 | 2.60 | 1.91 | 100.0 | 10.47 |
| Dataset | Train | Test |
| ThermalGaussian | RotaryKiln, DarkScenes Truck, PlantEquipment DailyStuff, LandScape RoadBlock, Dimsum Building, GlassCup TransmissionTower | Parterre, IronIngot Ebike |
| ThermalNeRF | engine, heater trace, sheet generators, charger pyrex | sink, generator |
| ThermoScenes | trees, heater_water_cup reflect-laptop, double_robot dorm1, raspberrypi buildingA_spring, MED-building buildingA_winter, reflect-cup exhibition_building, dorm2 reflect-kettle, building-sunrise BI-building, prpt-fridge heater_water_kettle | reflect-robot, freezing_ice_cup prpt-cup, melting_ice_cup INR-building |
| ThermalMix | hand, lion face, pan | panel, laptop |
| RF | 02_Fox_area_no_radars_0 02_Fox_area_no_radars_1 02_Fox_area_no_radars_2 02_Fox_area_no_radars_3 05_Return_from_the_forest_no_radar_0 05_Return_from_the_forest_no_radar_1 06_Sunset_area_no_radars_0 06_Sunset_area_no_radars_1 06_Sunset_area_no_radars_2 | 01_Annexet_No_Radars_0 01_Annexet_No_Radars_1 01_Annexet_No_Radars_2 01_Annexet_No_Radars_3 04_Forest_pass_no_radars_0 04_Forest_pass_no_radars_1 |
| SEAR dataset | – | conference-room, metallic-container old-drinking-fountain, parking statue, telescope |
3D Reconstruction
3D reconstruction recovers a scene’s shape, appearance, and camera motion from images, video, depth, or other sensor measurements.
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