EventFly: Event Camera Perception from Ground to the Sky


NUS       CNRS@CREATE       NUAA       I2R, A*STAR       IPAL, CNRS IRL 2955, Singapore CerCo, CNRS UMR 5549, Université Toulouse III

CVPR 2025

Key discrepancies across the Vehicle (Pv), Drone (Pd), and Quadruped (Pq) platforms. We compare the core attributes (viewpoint, speed, stability), event data distributions, and semantic distributions across event data acquired by three platforms, highlighting the challenges of adapting event camera perception to diverse operational contexts. These variations motivate the need for a robust cross-platform adaptation framework to harmonize event-based dense perception across distinct environmental setups and conditions.


Abstract

Cross-platform adaptation in event-based perception is crucial for deploying event cameras across diverse settings, such as Vehicles, Drones, and Quadrupeds, each with unique motion dynamics, viewpoints, and class distributions. In this work, we introduce EventFly, a framework for robust cross-platform adaptation in event camera perception.

Our approach comprises three key components: (i) Event Activation Prior (EAP), which identifies high-activation regions in the target domain to minimize prediction entropy, fostering confident, domain-adaptive predictions; (ii) EventBlend, a data-mixing strategy that integrates source and target event voxel grids based on EAP-driven similarity and density maps, enhancing feature alignment; and (iii) EventMatch, a dual-discriminator technique that aligns features from source, target, and blended domains for better domain-invariant learning.

To holistically assess cross-platform adaptation abilities, we introduce EXPo, a large-scale benchmark with diverse samples across vehicle, drone, and quadruped platforms. Extensive experiments validate our effectiveness, demonstrating substantial gains over popular adaptation methods. We hope this work can pave the way for adaptive, high-performing event perception across diverse and complex environments.


  The EventFly Framework

Overview of the EventFly framework. Guided by the EAP principle, the pair of source and target event data Vv and Vd are mixed via the EventBlend operation, where the blending mask M is obtained by measuring the similarities between density maps Dv and d. The features Fv, Fd, and from the source, target, and blended domains are then used for EventMatch. This facilitates learning an intermediary representation that is both robust (source-aligned) and adaptable (target-sensitive).



Demo #1:  From Vehicle to Drone



Demo #2:  From Vehicle to Quadruped



Demo #3:  From Drone to Vehicle



The EXPo Dataset

The structure and sequence information among the Vehicle, Drone, and Quadruped platforms in our benchmark.

Platform Sequence Name # Frames Total
Vehicle horse 714 43,766
penno_small_loop 1,102
rittenhouse 9,752
ucity_small_loop 16,867
city_hall 7,453
penno_big_loop 7,878
Drone fast_flight_1 2,229 19,899
fast_flight_2 4,077
penno_parking_1 2,810
penno_parking_2 2,713
penno_plaza 1,694
penno_cars 3,073
penno_trees 3,303
Quadruped penno_short_loop 2,942 25,563
skatepark_1 2,305
skatepark_2 1,652
srt_green_loop 1,597
srt_under_bridge_1 5,083
srt_under_bridge_2 4,533
art_plaza_loop 3,615
rocky_steps 3,836


  Platform-Specific Semantic Distributions

The distributions of Vehicle, Drone, and Quadruped are denoted by the • Green, • Red, and • Blue colors, respectively.


Road

Sidewalk

Building

Wall

Fence

Pole

Traffic Light

Traffic Sign

Vegetation

Terrain

Sky

Person

Rider

Car

Truck

Bus

Train

Motorcycle

Bicycle



   Semantic Distributions Maps

ID Class Type Vehicle Drone Quadruped
0 road static
1 sidewalk static
2 building static
3 wall static
4 fence static
5 pole static
6 traffic-light static
7 traffic-sign static
8 vegetation static
9 terrain static
10 sky static
11 person dynamic
12 rider dynamic
13 car dynamic
14 truck dynamic
15 bus dynamic
16 train dynamic
17 motorcycle dynamic
18 bicycle dynamic


Platform Adaptation from Vehicle to Drone

Note: Target is trained with ground truth from the target domain. All scores are given in percentage (%). The best and second best scores under each metric are highlighted in colors.

Method Acc mAcc mIoU fIoU ground building fence person pole road sidewalk vegetation car wall traffic-sign
Source-Only 43.69 33.81 15.04 11.81 48.71 11.57 0.92 8.42 13.33 25.48 8.18 31.51 14.88 0.04 2.41
AdaptSegNet 49.14 35.38 21.16 12.15 29.37 23.57 0.17 0.48 13.45 38.23 17.85 48.73 29.42 35.55 0.40
CBST 57.95 41.18 24.31 16.02 33.05 24.43 0.00 3.08 18.24 56.32 16.84 56.15 23.61 35.65 0.00
IntraDA 57.37 38.85 23.58 15.91 32.31 23.17 0.00 4.90 14.91 56.70 18.67 54.94 20.71 33.08 0.00
DACS 59.81 42.01 27.07 16.14 35.16 26.12 0.18 4.11 18.49 55.64 21.74 56.81 34.69 44.73 0.05
MIC 63.11 45.60 28.87 17.46 41.40 25.19 0.01 10.11 22.86 59.25 20.84 58.86 33.95 44.18 0.90
PLSR 64.61 45.93 29.69 17.99 42.09 30.06 0.00 9.75 23.32 62.48 20.65 60.15 31.69 44.27 2.06
EventFly 69.17 48.20 32.67 20.01 46.64 30.55 1.27 10.91 25.50 67.17 24.21 61.01 41.30 44.54 6.21
Target 79.57 52.25 42.90 23.30 74.48 39.40 7.10 0.33 31.67 71.96 31.64 67.87 57.51 66.14 23.79


Platform Adaptation from Vehicle to Quadruped

Note: Target is trained with ground truth from the target domain. All scores are given in percentage (%). The best and second best scores under each metric are highlighted in colors.

Method Acc mAcc mIoU fIoU ground building fence person pole road sidewalk vegetation car wall traffic-sign
Source-Only 66.59 39.73 25.15 16.52 63.01 39.26 3.88 17.88 10.12 51.67 9.27 68.02 12.35 0.24 0.99
AdaptSegNet 67.25 48.73 32.79 14.89 45.00 45.88 30.00 34.92 12.22 55.50 15.85 73.84 16.07 31.35 0.00
CBST 69.25 49.58 35.06 14.95 47.39 54.68 34.27 36.83 13.78 56.15 18.13 74.23 16.18 34.06 0.00
IntraDA 68.29 48.91 34.25 14.82 43.75 55.36 32.64 33.39 11.60 55.31 17.00 76.00 20.30 31.40 0.00
DACS 69.55 53.88 36.51 14.66 43.72 57.27 38.43 35.42 14.02 57.10 18.43 76.16 24.79 36.21 0.00
MIC 70.78 49.22 36.93 15.60 51.71 51.73 33.54 38.10 9.44 54.27 20.74 74.40 29.79 41.78 0.70
PLSR 70.91 53.65 37.57 15.25 49.04 53.28 37.54 36.64 12.91 57.60 25.29 75.92 24.92 39.85 0.24
EventFly 73.42 54.14 40.05 15.78 50.07 61.33 39.17 41.97 12.83 59.14 23.51 79.80 27.26 42.65 2.86
Target 80.02 60.55 49.84 19.58 74.80 56.23 46.08 55.28 21.79 59.90 30.31 77.24 58.38 62.47 5.81


BibTeX

@inproceedings{kong2025eventfly,
  title     = {EventFly: Event Camera Perception from Ground to the Sky},
  author    = {Lingdong Kong and Dongyue Lu and Xiang Xu and Lai Xing Ng and Wei Tsang Ooi and Benoit R. Cottereau},
  booktitle = {Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR)},
  year      = {2025},
}


Acknowledgments

This work is under the programme DesCartes and is supported by the National Research Foundation, Prime Minister’s Office, Singapore, under its Campus for Research Excellence and Technological Enterprise (CREATE) programme.

This work is also supported by the Apple Scholars in AI/ML Ph.D. Fellowship program.