Scaling Dense Event-Stream Pretraining from Visual Foundation Models
Organizations: City University of Hong Kong · Xidian University
Abstract
Learning versatile, fine-grained representations from irregular event streams is pivotal yet nontrivial, primarily due to the heavy annotation that hinders scalability in dataset size, semantic richness, and application scope. To mitigate this dilemma, we launch a novel self-supervised pretraining method that distills visual foundation models (VFMs) to push the boundaries of event representation at scale. Specifically, we curate an extensive synchronized image-event collection to amplify cross-modal alignment. Nevertheless, due to inherent mismatches in sparsity and granularity between image-event domains, existing distillation paradigms are prone to semantic collapse in event representations, particularly at high resolutions. To bridge this gap, we propose to extend the alignment objective to semantic structures provided off-the-shelf by VFMs, indicating a broader receptive field and stronger supervision. The key ingredient of our method is a structure-aware distillation loss that grounds higher-quality image-event correspondences for alignment, optimizing dense event representations. Extensive experiments demonstrate that our approach takes a great leap in downstream benchmarks, significantly surpassing traditional methods and existing pretraining techniques. This breakthrough manifests in enhanced generalization, superior data efficiency and elevated transferability.
Figures & tables
| Method | Backbone | DDD17-Seg | DSEC-Semantic | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| LP | 1% | 5% | 10% | 20% | Full | LP | 1% | 5% | 10% | 20% | Full | ||
| MaskCLIP [ 95 ] | ViT-B/16 | 31.91 | 53.91 | 56.27 | 59.32 | 59.97 | 61.27 | 33.08 | 33.89 | 37.03 | 38.83 | 42.40 | 55.01 |
| FC-CLIP [ 91 ] | ConvNeXt-L | 54.07 | 56.38 | 58.50 | 60.05 | 60.85 | 62.01 | 43.00 | 39.12 | 43.71 | 44.09 | 47.77 | 55.67 |
| OpenESS [ 41 ] | E2VID | 55.61 | 57.58 | 59.07 | 61.03 | 61.78 | 63.00 | 44.26 | 41.41 | 44.97 | 46.25 | 48.28 | 57.21 |
| Ours | ViT-B/16 | 57.87 | 57.23 | 59.54 | 61.45 | 62.06 | 62.81 | 58.42 | 54.37 | 62.82 | 63.88 | 64.15 | 64.93 |
| Method | Present at | Backbone | DDD17 | DSEC | ||
| Acc | mIoU | Acc | mIoU | |||
| RGB initialization + Fully-Supervised | ||||||
| Ev-SegNet [ 1 ] | CVPRW’19 | Xception | 89.76 | 54.81 | 88.61 | 51.76 |
| E2VID [ 64 ] | TPAMI’19 | ResNet-18 | 85.84 | 48.47 | 80.06 | 44.08 |
| DTL [ 74 ] | ICCV’21 | ResNet-50 | - | 58.80 | - | - |
| PVT-FPN [ 77 ] | ICCV’21 | ResNet-34 | 94.28 | 53.89 | - | - |
| Method | Present at | Backbone | MVSEC-Depth | DSEC-Depth | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| AbsRel | RMSE | RMSE log | AbsRel | RMSE | RMSE log | |||||||||
| RGB initialization + Fully-Supervised | ||||||||||||||
| E2Depth [ 30 ] | 3DV’20 | ResNet-18 | 0.432 | 0.717 | 0.868 | 0.420 | 7.268 | 0.455 | 0.409 | 0.719 | 0.891 | 0.395 | 13.258 | 0.412 |
| EReFormer [ 54 ] | TVSVT’24 | Swin-T | 0.391 | 0.652 | 0.810 | 0.551 | 8.373 | 0.523 | 0.524 | 0.824 | 0.945 | 0.297 | 11.608 | 0.334 |
| Event Pretraining + Fully-Supervised | ||||||||||||||
| ECDP [ 89 ] | ICCV’23 | ViT-S/16 | 0.476 | 0.772 | 0.863 | 0.496 | 7.680 | 0.506 | 0.528 | 0.818 | 0.938 | 0.324 | 11.473 | 0.376 |
| Method | Backbone | MVSEC-Depth | DSEC-Depth | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| LP | 1% | 5% | 10% | 20% | Full | LP | 1% | 5% | 10% | 20% | Full | ||
| DepthAnyEvent-R [ 4 ] | ViT-S/16 | 7.473 | 7.542 | 7.261 | 6.794 | 6.637 | 6.465 | 10.584 | 10.347 | 9.898 | 9.534 | 9.065 | 8.880 |
| Ours | ViT-S/16 | 6.756 | 6.930 | 6.712 | 6.477 | 6.352 | 6.145 | 4.861 | 4.983 | 4.751 | 4.728 | 4.694 | 4.564 |
| Exp. | Distill | Mask | IS Loss | CS Loss | DDD17-Seg | DSEC-Semantic | MVSEC-Depth | DSEC-Depth | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Acc | mIoU | Acc | mIoU | RMSE | RMSE | |||||||
| (a) | 91.39 | 59.60 | 91.94 | 64.31 | 0.593 | 6.635 | 0.846 | 4.424 | ||||
| (b) | 92.16 | 62.41 | 92.74 | 66.17 | 0.609 | 6.114 | 0.875 | 4.063 | ||||
| (c) | 92.32 | 62.67 | 92.82 | 66.54 | 0.611 | 5.922 | 0.876 | 4.025 | ||||
| (d) | 92.60 | 64.84 | 93.08 | 69.20 | 0.620 | 5.684 | 0.889 | 3.792 | ||||
| (e) | 92.51 | 63.62 | 93.01 | 68.68 | 0.614 | 5.786 | 0.881 | 3.870 | ||||
| Method | Backbone | indoor flying1 | indoor flying2 | indoor flying3 | |||
|---|---|---|---|---|---|---|---|
| EPE | Out | EPE | Out | EPE | Out | ||
| RGB initialization + Fully-Supervised | |||||||
| EST [ 22 ] | ResNet-18 | 1.24 | 5.09 | 2.05 | 19.90 | 1.71 | 11.67 |
| DCEFlow [ 73 ] | - | 0.75 | 0.60 | 1.39 | 8.01 | 1.13 | 5.29 |
| Event Pretraining + Fully-Supervised | |||||||
| ECDP [ 89 ] | ResNet-50 | 0.60 | 0.35 | 1.35 | 8.57 | 1.12 | 5.26 |
| Dataset | Semantic Segmentation | Depth Estimation | Flow Estimation | ||
| DDD17-Seg | DSEC-Semantic | MVSEC-Depth | DSEC-Depth | MVSEC-Flow | |
| optimizer | AdamW | AdamW | AdamW | AdamW | AdamW |
| encoder lr | |||||
| decoder lr | |||||
| weight decay | |||||
| batch size | 40 | 12 | 40 | 12 | 24 |
| Event Model | mIoU | flat | background | object | vegetation | human | vehicle | Acc |
|---|---|---|---|---|---|---|---|---|
| Linear Probing | ||||||||
| ViT-S/16 | 55.64 | 79.61 | 91.18 | 15.90 | 57.51 | 22.02 | 67.72 | 91.27 |
| ViT-B/16 | 57.87 | 79.92 | 91.24 | 15.87 | 58.04 | 34.97 | 67.05 | 91.31 |
| ViT-L/16 | 60.30 | 81.03 | 91.49 | 18.83 | 57.21 | 44.18 | 68.95 | 91.83 |
| Fine-Tuning (1 ) | ||||||||
| ViT-S/16 | 53.87 | 78.61 | 90.06 | 10.03 | 54.59 | 25.18 | 64.63 | 90.41 |
| Event Model | indoor flying1 | indoor flying2 | indoor flying3 | |||
|---|---|---|---|---|---|---|
| EPE | Out | EPE | Out | EPE | Out | |
| ViT-S/16 | 0.29 | 0.03 | 0.38 | 0.001 | 0.40 | 0.001 |
| ViT-B/16 | 0.28 | 0.03 | 0.38 | 0.001 | 0.39 | 0.001 |
| ViT-L/16 | 0.27 | 0.03 | 0.37 | 0.001 | 0.39 | 0.001 |
| Event Model | mIoU | background | building | fence | person | pole | road | sidewalk | vegetation | car | wall | traffic-sign | Acc |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linear Probing | |||||||||||||
| ViT-S/16 | 55.46 | 92.81 | 81.88 | 17.45 | 15.67 | 24.98 | 93.20 | 68.12 | 78.83 | 77.72 | 30.79 | 43.86 | 90.12 |
| ViT-B/16 | 58.42 | 93.46 | 83.52 | 23.88 | 16.69 | 27.85 | 93.72 | 69.27 | 80.38 | 80.13 | 43.06 | 43.25 | 91.44 |
| ViT-L/16 | 61.29 | 93.91 | 85.09 | 27.66 | 27.37 | 33.58 | 93.34 | 70.94 | 82.37 | 82.27 | 41.82 | 48.66 | 91.69 |
| Fine-Tuning (1 ) | |||||||||||||
| ViT-S/16 | 52.97 | 92.35 | 81.36 | 18.04 | 7.93 | 18.77 | 92.55 | 60.54 | 78.50 | 76.22 | 22.25 | 37.06 | 89.56 |
| Event Model | Metric | MVSEC-Depth | DSEC-Depth | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| LP | 1% | 5% | 10% | 20% | Full | LP | 1% | 5% | 10% | 20% | Full | ||
| ViT-S/16 | 0.529 | 0.526 | 0.531 | 0.542 | 0.560 | 0.577 | 0.798 | 0.795 | 0.804 | 0.811 | 0.816 | 0.824 | |
| RMSE | 6.756 | 6.930 | 6.712 | 6.477 | 6.352 | 6.145 | 4.861 | 4.983 | 4.751 | 4.728 | 4.694 | 4.564 | |
| ViT-B/16 | 0.571 | 0.561 | 0.574 | 0.587 | 0.591 | 0.594 | 0.845 | 0.839 | 0.856 | 0.863 | 0.867 | 0.872 | |
| RMSE | 6.392 | 6.546 | 6.339 | 6.012 | 5.908 | 5.891 | 4.352 | 4.471 | 4.264 | 4.192 | 4.154 | 4.032 | |
| ViT-L/16 | 0.597 | 0.592 | 0.601 | 0.612 | 0.619 | 0.625 | 0.881 | 0.856 | 0.883 | 0.892 | 0.893 | 0.896 | |
| Event Input | DDD17-Seg | DSEC-Depth | MVSEC-Flow | |||
|---|---|---|---|---|---|---|
| Acc | mIoU | RMSE | EPE | Out | ||
| Color Frame | 90.76 | 56.37 | 0.784 | 5.306 | 1.107 | 6.720 |
| E2VID | 89.25 | 55.72 | 0.809 | 4.928 | 0.852 | 3.294 |
| Event Volume | 91.39 | 59.64 | 0.824 | 4.564 | 0.356 | 0.094 |
| Time Bin | DDD17-Seg | DSEC-Depth | MVSEC-Flow | |||
|---|---|---|---|---|---|---|
| Acc | mIoU | RMSE | EPE | Out | ||
| 91.07 | 58.43 | 0.819 | 4.736 | 0.365 | 0.104 | |
| 91.39 | 59.64 | 0.824 | 4.564 | 0.356 | 0.094 | |
| 91.20 | 59.22 | 0.822 | 4.613 | 0.359 | 0.095 | |
| Density | DDD17-Seg | DSEC-Depth | MVSEC-Flow | |||
|---|---|---|---|---|---|---|
| Threshold | Acc | mIoU | RMSE | EPE | Out | |
| 91.33 | 59.51 | 0.823 | 4.538 | 0.362 | 0.095 | |
| 91.39 | 59.64 | 0.824 | 4.564 | 0.356 | 0.094 | |
| 91.25 | 59.32 | 0.821 | 4.640 | 0.367 | 0.097 | |
| Alignment | DDD17-Seg | DSEC-Depth | MVSEC-Flow | |||
|---|---|---|---|---|---|---|
| Objective | Acc | mIoU | RMSE | EPE | Out | |
| patch-level (L1) | 90.65 | 56.06 | 0.785 | 4.990 | 0.367 | 0.098 |
| superpixel-level (L1) | 90.88 | 56.36 | 0.790 | 4.937 | 0.384 | 0.106 |
| superpixel-level (CL) | 90.92 | 56.72 | 0.782 | 5.031 | 0.435 | 0.120 |
| ours | 91.39 | 59.64 | 0.824 | 4.564 | 0.356 | 0.094 |
| Alignment | DDD17-Seg | DSEC-Depth | MVSEC-Flow | |||
|---|---|---|---|---|---|---|
| Objective | Acc | mIoU | RMSE | EPE | Out | |
| multi-scale | 91.07 | 58.83 | 0.816 | 4.831 | 0.377 | 0.102 |
| single-scale | 91.39 | 59.64 | 0.824 | 4.564 | 0.356 | 0.094 |
| Segment Model | Depth Model | Flow Model | ||||
| MParams | GFLOP | MParams | GFLOPs | MParams | GFLOPs | |
| ViT-S | 28.23 | 243.67 | 18.92 | 61.23 | 40.95 | 349.42 |
| ViT-B | 76.74 | 363.82 | 74.98 | 231.93 | 135.62 | 962.71 |
| ViT-L | 239.09 | 758.17 | 257.29 | 853.16 | 485.27 | 3369.48 |
Event-Based Vision
Event-based vision uses asynchronous camera measurements to perceive motion and scene changes with high temporal resolution and dynamic range.
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