Open-Vocabulary Domain Generalization in Urban-Scene Segmentation
Organizations: Department of Information Engineering and Computer Science, University of Trento, Italy · School of Computer Science and Information Engineering, Hefei University of Technology, China
Abstract
Domain Generalization in Semantic Segmentation (DG-SS) aims to enable segmentation models to perform robustly in unseen environments. However, conventional DG-SS methods are restricted to a fixed set of known categories, limiting their applicability in open-world scenarios. Recent progress in Vision-Language Models (VLMs) has advanced Open-Vocabulary Semantic Segmentation (OV-SS) by enabling models to recognize a broader range of concepts. Yet, these models remain sensitive to domain shifts and struggle to maintain robustness when deployed in unseen environments, a challenge that is particularly severe in urban-driving scenarios. To bridge this gap, we introduce Open-Vocabulary Domain Generalization in Semantic Segmentation (OVDG-SS), a new setting that jointly addresses unseen domains and unseen categories. We introduce the first benchmark for OVDG-SS in autonomous driving, addressing a previously unexplored problem and covering both synthetic-to-real and real-to-real generalization across diverse unseen domains and unseen categories. In OVDG-SS, we observe that domain shifts often distort text-image correlations in pre-trained VLMs, which hinders the performance of OV-SS models. To tackle this challenge, we propose S2-Corr, a state-space-driven text-image correlation refinement mechanism that mitigates domain-induced distortions and produces more consistent text-image correlations under distribution changes. Extensive experiments on our constructed benchmark demonstrate that the proposed method achieves superior cross-domain performance and efficiency compared to existing OV-SS approaches.
Figures & tables
| OV-SS Method | Training Data | Seen | Num. | Shared classes | Performance | ||
| class | Dv-19 | Dv-58 | Dv-19 | Dv-58 | |||
| CAT-Seg [ 7 ] | COCO-Stuff [ 27 ] | 171 | 118K | 17 | 34 | 31.6 | 32.4 |
| CAT-Seg | SYNTHIA [ 43 ] | 7 | 9.4K | 7 | 7 | 43.6 | 45.3 |
| CAT-Seg | GTA [ 41 ] | 7 | 25K | 7 | 7 | 47.5 | 48.2 |
| CAT-Seg | Cityscapes [ 8 ] | 7 | 3K | 7 | 7 | 49.3 | 50.0 |
| MaskAdapter [ 24 ] | COCO-Stuff | 171 | 118K | 17 | 34 | 30.1 | 29.6 |
| Method | Backbone | Training Data | Dv-19 | Ave. | Dv-58 | Ave. | |||||
| ACDC-19 | BDD-19 | Mapi-19 | ACDC-41 | BDD-41 | Mapi-30 | RW-10 | |||||
| CLIP-DINOiser(ECCV2024) [ 55 ] | EVA02+DINOV2 ViT-L | Training-Free | 25.3 | 28.5 | 27.7 | 27.2 | 31.9 | 34.0 | 26.9 | 21.6 | 28.6 |
| ClearCLIP(ECCV2024) [ 19 ] | EVA02 ViT-L | Training-Free | 26.7 | 28.3 | 27.0 | 27.3 | 33.5 | 34.0 | 26.6 | 21.6 | 28.9 |
| ProxyCLIP (ECCV’24) [ 20 ] | EVA02+SAM ViT-L | Training-Free | 31.0 | 38.2 | 40.0 | 36.4 | 38.5 | 52.2 | 33.5 | 27.2 | 37.9 |
| CAT-Seg (CVPR’24) [ 7 ] | EVA02 ViT-L/14 | COCO | 30.3 | 31.9 | 36.1 | 32.8 | 33.2 | 42.8 | 28.6 | 27.6 | 33.1 |
| DeCLIP (CVPR’25) [ 49 ] | EVA02+DINOV2 ViT-L | COCO | 32.1 | 31.8 | 38.1 | 34.0 | 34.2 | 47.0 | 32.0 | 28.3 | 35.4 |
| Method | Backbone | Training Data | Dv-19 | Ave. | Dv-58 | Ave. | ||||||
| CS-19 | ACDC-19 | BDD-19 | Mapi-19 | ACDC-41 | BDD-41 | Mapi-30 | RW-10 | |||||
| OVSeg (CVPR’23) [ 26 ] | EVA02 ViT-B/16 | GTA-7 | 41.2 | 34.9 | 42.5 | 45.1 | 40.9 | 45.1 | 52.6 | 35.5 | 32.9 | 41.5 |
| SAN (CVPR’23) [ 56 ] | GTA-7 | 43.3 | 36.7 | 42.0 | 48.1 | 42.5 | 47.7 | 49.0 | 37.8 | 30.3 | 41.2 | |
| CAT-Seg (CVPR’24) [ 7 ] | GTA-7 | 43.7 | 37.6 | 45.4 | 48.8 | 43.9 | 51.2 | 56.2 | 39.3 | 35.7 | 45.6 | |
| MAFT+(ECCV’24) [ 16 ] | GTA-7 | 45.7 | 38.5 | 43.7 | 50.2 | 44.5 | 49.1 | 48.3 | 39.9 | 31.8 | 42.3 | |
| ESC-Net (CVPR’25) [ 21 ] | GTA-7 | 42.2 | 35.9 | 44.6 | 48.1 | 42.7 | 49.4 | 52.4 | 37.9 | 33.3 | 43.3 | |
| Note | Methods | ViT-B/16 | ViT-L/14 | Ave. | ||
| Dv-19 | Dv-58 | Dv-19 | Dv-58 | |||
| Base | Cross-attention | 43.5 | 43.5 | 49.3 | 50.0 | 46.6 |
| #1 | Seletive SSM | 45.6 | 44.1 | 50.7 | 50.5 | 47.7 |
| #2 | +Modulation | 47.6 | 45.3 | 52.1 | 50.9 | 49.0 |
| #3 | +Geometric decay | 48.3 | 46.4 | 53.2 | 51.8 | 49.9 |
| #4 | +Chunk | 49.6 | 47.3 | 55.3 | 52.7 | 51.2 |
| Model | FPS | FPS | FPS | GPU | Training |
| vocab19 | vocab58 | vocab150 | Mem. (GB) | Time (min) | |
| CAT-Seg [ 7 ] | 15.4 | 10.6 | 5.7 | 13.8 | 180 |
| ESC-Net [ 21 ] | 15.0 | 9.9 | 5.1 | 15.7 | 220 |
| Seletive SSM | 12.3 | 9.4 | 6.4 | 16.8 | 240 |
| S 2 -Corr (Ours) | 26.1 | 22.2 | 18.3 | 9.2 | 140 |
| dataset | From | Size | Resolution | Classes |
| CS-7 | Cityscapes Train [ 8 ] | 2,975 | 2048×1024 | Rd, Sw, Bldg, Veg, Sky, Per, Car |
| GTA-7 | GTA Train [ 41 ] | 24999 | 2048×1024 | |
| ACDC-19 | ACDC Train [ 44 ] | 1,600 | 1920×1080 | Rd, Sw, Bldg, Wal, Fen, Pol, TL, TS |
| BDD-19 | BDD100K Validation [ 60 ] | 1000 | 1280×720 | Veg, Ter, Sky, Per, Rid, Car, Trk, Bus, Trn, Mot, Bic |
| Mapi-19 | Mapillary Validation [ 60 ] | 2000 | 2k-4k | |
| ACDC-41 | SD 2.1 + ACDC Train | 1000 | 1920×1080 | Rd, Sw, Bldg, Wal, Fen, Pol, TL, TS, Veg, Ter, Sky, Per, |
| VLM | ACDC-19 | BDD-19 | Mapi-19 | ACDC-41 | BDD-41 | Mapi-30 | RW-10 | Ave. |
| EVA-02-CLIP-L/14 [ 11 ] | 54.3 | 53.1 | 60 | 62 | 61.7 | 47.4 | 41.9 | 44.7 |
| SigLIP-ViT-L/16 [ 48 ] | 52.7 | 54.1 | 59.2 | 60.5 | 60.4 | 48.3 | 42.5 | 54.0 |
| CLIP-ViT-L/14 [ 39 ] | 53.7 | 52.8 | 59.0 | 61.6 | 60.9 | 46.7 | 40.9 | 53.7 |
| SelfCLIP-ViT-L/14 [ 52 ] | 56.3 | 53.6 | 60.9 | 63.8 | 63.5 | 48.1 | 41.9 | 59.6 |
| Variant | Row | Col | mIoU Dv-19 | mIoU Dv-58 | Training Time (Min) |
| Row-only (ours) | 50.3 | 47.9 | 140 | ||
| Col | 48.6 | 45.7 | 140 | ||
| Row+Col | 50.4 | 48.1 | 165 |
| Training Data: GTA-19 | |||||||||||
| Type | Pretrain | CS-19 | BDD-19 | Mapi-19 | Ave. | Mapi-30 | RW-10 | ACDC-41 | BDD-41 | Ave. | |
| Rein (CVPR’24) [ 50 ] | DG | EVA02-L | 65.3 | 60.5 | 64.9 | 63.6 | - | - | - | - | - |
| tqdm (ECCV’24) [ 36 ] | DG | EVA02-L | 68.9 | 59.2 | 70.1 | 66.1 | - | - | - | - | - |
| SoMA (CVPR’25) [ 61 ] | DG | EVA02-L | 68.1 | 60.8 | 68.3 | 65.7 | - | - | - | - | - |
| MaskAdapter (CVPR’25) [ 24 ] | OVSS | EVA02-L | 61.5 | 55.5 | 65.7 | 60.9 | 48.5 | 41.0 | 63.3 | 61.8 | 53.7 |
| MAFT+(ECCV24) [ 16 ] | OVSS | EVA02-L | 61.2 | 55.0 | 65.0 | 61.2 | 48.2 | 40.1 | 63.9 | 62.4 | 53.7 |
| Methods | FS Static | FS Lost&Found | SMIYC-Anomaly | SMIYC-Obstacle | RoadAnomaly | |||||
| IoU | mean F1 | IoU | mean F1 | IoU | mean F1 | IoU | mean F1 | IoU | mean F1 | |
| Synboost [ 10 ] | 32.8 | 25.7 | 18.4 | 10.9 | 42.0 | 39.5 | 14.0 | 9.0 | 27.2 | 29.3 |
| PEBAL [ 47 ] | 26.9 | 13.3 | 6.4 | 2.6 | 42.4 | 35.1 | 6.7 | 1.1 | 33.8 | 23.9 |
| RPL+CoroCL [ 31 ] | 36.5 | 13.2 | 15.8 | 3.9 | 68.8 | 31.6 | 28.7 | 5.7 | 51.0 | 24.6 |
| S2M [ 70 ] | 70.0 | 70.2 | 30.5 | 35.3 | 77.5 | 60.4 | 67.6 | 65.0 | 58.5 | 61.7 |
| Ours | 74.6 | 76.7 | 36.3 | 42.2 | 82.9 | 69.7 | 76.2 | 73.8 | 66.5 | 66.9 |
| Method | Backbone | Training Data | Dv-19 | Ave. | Dv-58 | Ave. | |||||
| ACDC-19 | BDD-19 | Mapi-19 | ACDC-41 | BDD-41 | Mapi-30 | RW-10 | |||||
| CLIP-DINOiser(ECCV2024) [ 55 ] | CLIP+DinoV2 ViT-L/14 | Training-Free | 25.3 | 28.5 | 27.7 | 27.2 | 31.9 | 34.0 | 26.9 | 21.6 | 28.6 |
| ClearCLIP(ECCV2024) [ 19 ] | CLIP ViT-L/14 | Training-Free | 26.7 | 28.3 | 27.0 | 27.3 | 33.5 | 34.0 | 26.6 | 21.6 | 28.9 |
| ProxyCLIP (ECCV’24) | CLIP+SAM ViT-L/14 | Training-Free | 31.0 | 38.2 | 40.0 | 36.4 | 38.5 | 52.2 | 33.5 | 27.2 | 37.9 |
| OVSeg (CVPR’23) [ 26 ] | EVA02 ViT-L/14 | CS-7 | 41.9 | 42.6 | 43.9 | 42.8 | 51.2 | 49.3 | 33.7 | 35.7 | 42.5 |
| SAN (CVPR’23) [ 56 ] | CS-7 | 46.6 | 47.0 | 48.3 | 47.3 | 57.5 | 56.9 | 38.0 | 34.8 | 46.8 | |
| CS-7→ACDC-19 ViT-B/16 | ||||||||||||||||||||
| Methods | Rd | Sw | Bldg | Veg | Sky | Per | Car | Wal | Fen | Pol | TL | TS | Ter | Rid | Trk | Bus | Trn | Mot | Bic | mIoU |
| OVSeg (CVPR’23) [ 26 ] | 83.3 | 37.5 | 85.5 | 69.1 | 80.5 | 43.8 | 68.2 | 29.3 | 21.0 | 8.9 | 8.6 | 7.8 | 13.0 | 2.3 | 42.6 | 35.7 | 9.4 | 16.5 | 32.9 | 36.6 |
| SAN (CVPR’23) [ 56 ] | 86.4 | 34.5 | 82.6 | 73.6 | 96.5 | 49.8 | 71.2 | 31.0 | 18.2 | 7.5 | 7.0 | 5.7 | 14.3 | 0.1 | 46.1 | 32.7 | 9.0 | 17.2 | 30.9 | 37.6 |
| CAT-Seg (CVPR’24) [ 7 ] | 82.2 | 39.8 | 84.8 | 73.5 | 92.0 | 49.3 | 78.9 | 34.9 | 20.4 | 8.8 | 8.5 | 7.2 | 15.4 | 2.3 | 44.6 | 34.6 | 11.1 | 18.4 | 32.0 | 38.9 |
| CLIPSelf (ICLR’24) [ 52 ] | 84.9 | 38.9 | 73.1 | 72.0 | 89.1 | 45.4 | 74.7 | 27.9 | 31.6 | 24.9 | 24.5 | 32.8 | 18.3 | 14.5 | 40.3 | 35.5 | 12.1 | 31.8 | 36.5 | 42.6 |
| RSC-CLIPSelf (ICLR’25) [ 38 ] | 74.4 | 39.1 | 83.0 | 74.4 | 73.9 | 44.9 | 69.7 | 26.7 | 27.5 | 23.4 | 27.5 | 28.6 | 16.5 | 12.5 | 38.2 | 30.2 | 11.6 | 29.9 | 36.2 | 40.4 |
| CS-7→ACDC-41 ViT-B/16 | ||||||||||||||||||||||||||||||||||||||||||
| Rd | Sw | Bldg | Veg | Sky | Per | Car | Wal | Fen | Pol | TL | TS | Ter | Rid | Trk | Bus | Trn | Mot | Bic | Bag | Bal | Bar | Bnc | Brd | Btl | Crt | Cat | Chr | Cow | Der | Dog | Drn | Elp | Hat | Hrs | Rbt | Shp | Tbl | Toy | Umb | Zbr | mIoU | |
| SAN (CVPR’23) [ 56 ] | 82.5 | 35.4 | 83.6 | 65.2 | 76.2 | 37.9 | 73.9 | 25.0 | 12.1 | 7.5 | 6.6 | 4.0 | 13.9 | 0.0 | 41.2 | 32.1 | 6.7 | 17.9 | 17.1 | 62.1 | 79.3 | 56.8 | 4.0 | 41.4 | 40.1 | 41.1 | 62.2 | 44.7 | 68.3 | 52.9 | 60.1 | 44.5 | 80.4 | 80.4 | 68.9 | 60.9 | 62.9 | 6.6 | 28.3 | 67.5 | 66.3 | 44.4 |
| CAT-Seg (CVPR’24) [ 7 ] | 83.5 | 42.4 | 81.4 | 65.3 | 85.4 | 39.6 | 71.9 | 29.4 | 14.3 | 8.9 | 7.9 | 5.6 | 15.0 | 1.4 | 46.5 | 33.6 | 10.1 | 20.7 | 17.6 | 69.0 | 76.2 | 60.4 | 7.1 | 49.4 | 44.1 | 51.3 | 75.3 | 53.3 | 66.9 | 51.7 | 68.3 | 49.3 | 76.6 | 83.3 | 67.1 | 62.2 | 71.2 | 8.1 | 30.3 | 74.6 | 76.2 | 47.6 |
| CLIPSelf (ICLR’24) [ 52 ] | 88.2 | 42.0 | 80.6 | 73.9 | 92.0 | 41.3 | 72.0 | 29.5 | 14.7 | 9.2 | 9.0 | 6.3 | 15.1 | 1.5 | 50.2 | 33.7 | 10.5 | 20.0 | 17.1 | 72.5 | 78.9 | 68.8 | 7.6 | 45.4 | 46.7 | 53.3 | 72.1 | 55.4 | 63.8 | 51.2 | 73.0 | 46.5 | 84.0 | 86.9 | 63.3 | 69.9 | 80.6 | 7.8 | 30.0 | 73.7 | 86.0 | 49.4 |
| RSC-CLIPSelf (ICLR’25) [ 38 ] | 88.2 | 44.0 | 88.5 | 74.5 | 92.6 | 40.1 | 69.3 | 28.8 | 16.1 | 8.7 | 8.8 | 6.1 | 15.1 | 1.6 | 50.1 | 37.0 | 10.5 | 21.7 | 18.2 | 75.1 | 74.8 | 76.3 | 8.1 | 48.1 | 45.1 | 57.4 | 72.8 | 58.2 | 63.3 | 54.7 | 74.9 | 49.7 | 79.1 | 82.1 | 60.3 | 73.1 | 80.6 | 7.7 | 32.2 | 70.9 | 84.2 | 50.0 |
| MAFT+(ECCV’24) [ 16 ] | 80.0 | 40.9 | 74.0 | 66.6 | 81.6 | 36.3 | 68.2 | 29.8 | 13.5 | 8.7 | 8.4 | 5.7 | 13.1 | 1.5 | 46.8 | 29.8 | 10.4 | 20.2 | 15.8 | 68.3 | 78.8 | 68.4 | 6.9 | 45.4 | 46.7 | 48.1 | 64.9 | 48.6 | 61.7 | 45.8 | 72.1 | 47.7 | 76.9 | 87.9 | 59.7 | 66.1 | 80.7 | 6.8 | 27.1 | 67.8 | 75.9 | 46.4 |
| CS-7→Map-30 ViT-B/16 | |||||||||||||||||||||||||||||||
| Rd | Sw | Bldg | Veg | Sky | Per | Car | Wal | Fen | Pol | TL | TS | Ter | Rid | Trk | Bus | Trn | Mot | Bic | Chr | Brg | Tun | Wtr | Snw | Snd | Anm | Sbd | Rwy | Bot | Tc | mIoU | |
| SAN (CVPR’23) [ 56 ] | 69.3 | 44.7 | 67.6 | 87.1 | 101.5 | 61.2 | 84.6 | 21.2 | 18.2 | 10.8 | 4.7 | 6.0 | 13.2 | 0.4 | 36.4 | 52.5 | 15.5 | 51.0 | 43.6 | 29.4 | 27.1 | 20.2 | 31.0 | 42.0 | 18.0 | 38.6 | 1.0 | 16.0 | 10.5 | 39.8 | 35.4 |
| CAT-Seg (CVPR’24) [ 7 ] | 78.0 | 43.0 | 81.6 | 82.5 | 95.8 | 62.7 | 83.9 | 30.7 | 20.4 | 13.3 | 6.9 | 8.1 | 17.8 | 2.5 | 45.0 | 54.9 | 18.8 | 48.5 | 42.3 | 31.2 | 32.0 | 44.2 | 32.3 | 43.9 | 19.3 | 37.1 | 3.1 | 15.7 | 11.1 | 40.4 | 38.2 |
| CLIPSelf (ICLR’24) [ 52 ] | 81.1 | 45.8 | 82.4 | 81.4 | 108.2 | 70.0 | 88.6 | 30.3 | 23.1 | 14.0 | 6.7 | 7.9 | 17.9 | 2.7 | 44.8 | 52.5 | 20.7 | 51.4 | 46.3 | 29.7 | 32.2 | 32.9 | 32.8 | 46.6 | 18.8 | 41.3 | 3.1 | 16.5 | 11.7 | 45.1 | 39.6 |
| RSC-CLIPSelf (ICLR’25) [ 38 ] | 80.1 | 45.6 | 88.4 | 86.1 | 98.0 | 65.4 | 82.8 | 29.9 | 25.6 | 13.7 | 6.2 | 7.7 | 16.8 | 3.1 | 49.0 | 48.5 | 18.9 | 55.1 | 49.5 | 29.5 | 34.5 | 44.2 | 37.0 | 51.8 | 17.6 | 43.3 | 2.9 | 15.4 | 13.3 | 42.8 | 40.1 |
| MAFT+(ECCV’24) [ 16 ] | 82.6 | 43.1 | 79.3 | 76.9 | 110.2 | 71.9 | 87.9 | 30.1 | 22.6 | 12.5 | 5.9 | 7.8 | 16.1 | 2.6 | 45.4 | 49.7 | 18.1 | 46.7 | 44.4 | 27.7 | 29.6 | 33.3 | 32.3 | 41.9 | 16.8 | 38.5 | 3.0 | 15.8 | 12.0 | 39.5 | 38.1 |
| CS-7→RW-10 ViT-B/16 | |||||||||||
| Rd | Sw | Bar | PV | WV | PO | Wkr | Con | ABd | TTC | mIoU | |
| SAN (CVPR’23) [ 56 ] | 80.3 | 37.9 | 58.7 | 3.8 | 41.6 | 28.7 | 32.4 | 6.8 | 3.7 | 12.7 | 30.7 |
| CAT-Seg (CVPR’24) [ 7 ] | 89.9 | 62.8 | 57.3 | 20.9 | 48.1 | 22.9 | 24.7 | 10.0 | 4.5 | 24.2 | 36.5 |
| CLIPSelf (ICLR’24) [ 52 ] | 88.1 | 62.9 | 58.8 | 20.0 | 49.5 | 23.5 | 24.8 | 9.5 | 4.5 | 23.8 | 36.5 |
| RSC-CLIPSelf (ICLR’25) [ 38 ] | 85.6 | 61.8 | 54.9 | 20.9 | 46.7 | 23.5 | 23.4 | 9.8 | 4.3 | 23.4 | 35.4 |
| MAFT+(ECCV’24) [ 16 ] | 89.4 | 55.9 | 51.4 | 20.9 | 44.8 | 20.8 | 23.8 | 9.7 | 4.3 | 23.8 | 34.5 |
Domain Generalization
Domain generalization develops models that perform reliably in new environments without training on target-domain data.
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