Single-stage multi-person pose estimation aims to jointly perform human localization and keypoint prediction within a unified framework, offering advantages in inference efficiency and architectural simplicity. Consequently, multi-scale real-time detection architectures, such as YOLO-like models, are widely adopted for real-time pose estimation. However, these approaches typically inherit a box-driven modeling paradigm from object detection, in which pose estimation is implicitly constrained by bounding-box supervision during training. This formulation introduces biases in sample assignment and feature representation, resulting in task misalignment and ultimately limiting pose estimation accuracy. In this work, we revisit box-driven single-stage pose estimation from a keypoint-driven perspective and identify semantic conflicts among parallel objectives as a key source of performance degradation. To address this issue, we propose a keypoint-driven learning paradigm that elevates pose estimation to a primary prediction objective. Specifically, we remove bounding-box prediction and redesign the prediction head to better accommodate the high-dimensional structured representations for pose estimation. We further introduce a keypoint-driven dynamic sample assignment strategy to align training objectives with pose evaluation metrics, enabling dense supervision during training and efficient NMS-free inference. In addition, we propose a smooth OKS-based loss function to stabilize optimization in regression-based pose estimation. Based on these designs, we develop a single-stage multi-person pose estimation framework, termed ER-Pose. On MS COCO and CrowdPose, ER-Pose-n achieves AP improvements of 3.2/6.7 without pre-training and 7.4/4.9 with pre-training respectively compared with the baseline YOLO-Pose. These improvements are achieved with fewer parameters and higher inference efficiency.
Figures & tables
Fig. 1 : Performance comparison between ER-Pose and representative human pose estimation methods on the COCO test-dev set. (a) Accuracy vs. inference time. (b) Accuracy vs. number of parameters. ER-Pose demonstrates superior inference efficiency while maintaining competitive accuracy.
Fig. 2 : Illustration of the typical box-driven pipeline: the bounding-box-centered single-stage pose estimation paradigm.
Fig. 3 : Overview of the ER-Pose framework. ER-Pose adopts keypoint-driven single-stage architecture. Feature extraction design follows YOLOv8, with CSPDarkNet [ 57 , 7 ] used as backbone and PAN [ 58 ] employed as neck to produce multi-scale features. Head consists of human confidence branch and pose branch. Confidence branch adopts DSConv [ 59 ] to reduce computational cost, while keypoint regression employs standard convolution to preserve sufficient representational capacity. Network is trained under MAH-SAH scheme.
Fig. 4 : Suboptimal keypoint feature selection induced by box-driven modeling. The upper part shows positive samples selected by the network, while the lower part presents samples from the same network that yield more accurate keypoint estimates but are suppressed during inference.
Fig. 5 : The assignment paradigm
Fig. 6 : Comparison of Gaussian, Laplace, and SOKS distributions.
Method
Backbone
Input Size
Params (M)
Latency (ms)
AP
AP50
AP75
HigherHRNet [ 21 ]
HRNet-W32 [ 17 ]
512 × 512
28.6
34.398
66.4
87.5
72.8
CenterNet [ 45 ]
Hourglass-3x [ 23 ]
512 × 512
194.9
45.855
63.0
86.8
69.6
DEKR [ 51 ]
HRNet-W32 [ 17 ]
512 × 512
29.6
33.935
68.0
86.7
74.5
DEKR [ 51 ]
HRNet-W48 [ 17 ]
640 × 512
65.7
36.585
71.0
88.3
77.4
CID [ 47 ]
HRNet-W32 [ 17 ]
512 × 512
29.4
45.678
68.9
88.5
76.6
ED-Pose [ 42 ]
ResNet-50 [ 63 ]
800 × 1333
50.6
171.971
69.8
90.2
77.2
TABLE I : Comparison results of ER-Pose with advanced methods on the COCO test-dev set. Inference latency was measured on one Tesla V100 GPU under identical hardware conditions, with evaluation performed using onnxruntime.
Input size
Latency(ms)
AP
AP50
AP75
AR
640
10.587
57.1
84.6
62.0
62.4
800
11.844
59.5
86.2
65.0
64.5
960
13.412
60.9
86.8
68.8
65.9
TABLE II : Comparison of model performance under different input Resolutions
Box branch
Keypoint-driven Assignment
AP
AP50
AP75
AR
✓
×
50.4
79.5
54.2
57.8
✓
✓
54.7
83.2
58.8
60.2
×
✓
57.1
84.6
62.0
62.4
TABLE III : Semantic ablation experiments on the box-based branch
Fig. 7 : Gradient heatmaps of confidence prediction branches for models of tiny and small variants. From left to right, results correspond to models using one, two, and three feature scales. (a) Grad-CAM visualization of ER-Pose-n. (b) Grad-CAM visualization of ER-Pose-s.
scale
features
AP
APm
APl
AR
ARm
ARl
n
{P5}
55.9
46.7
69.1
60.4
51.2
73.2
{P4, P5}
57.1
49.1
68.8
62.4
54.9
73.0
{P3, P4, P5}
56.4
47.5
68.9
61.6
53.4
73.0
s
{P5}
64.0
56.1
75.9
68.4
60.5
79.7
{P4, P5}
64.0
58.9
72.1
68.6
63.4
75.9
{P3, P4, P5}
65.7
58.7
75.9
70.5
63.9
79.7
TABLE IV : Branch ablation experiments
Fig. 8 : Gradient heatmaps of confidence prediction branches for models of tiny and small variants. From left to right, results correspond to models using one, two, and three feature scales. (a) Grad-CAM visualization of ER-Pose-n. (b) Grad-CAM visualization of ER-Pose-s.
scale
features
n
{P4, P5}
s
{P3, P4, P5}
m
{P3, P4, P5}
l
{P3, P4, P5}
TABLE V : Features maps protocol
IoU thr.
ER-Pose(OKS-IoU)
Box-driven(IoU)
AP
AR
NMS(ms)
AP
AR
NMS(ms)
0.4
57.1
61.5
7.434
49.9
56.3
0.978
0.5
57.0
61.7
8.769
50.1
56.7
1.085
0.6
56.9
61.8
9.746
50.3
57.1
1.034
0.7
56.6
61.9
12.199
50.4
57.4
1.040
0.8
56.2
62.2
13.791
50.4
57.8
0.951
TABLE VI : Model performance comparison under different positive sample assignment centers and NMS strategies
model
AP
AP50
AP75
AR
latency(ms)
SAH
53.1
81.8
56.7
58.8
10.587
MAH+NMS(OKS)
56.6
83.4
61.4
60.8
13.544
MAH+SAH
57.1
84.6
62.0
62.4
10.721
TABLE VII : Ablation results of multi-head structures. SAH denotes models trained using single-head assignment, where inference relies exclusively on SAH. Models using only MAH adopt OKS-based NMS during inference to suppress redundant predictions.
Fig. 9 : Grad-CAM visualizations of dual-head structures.
Fig. 10 : Visualization of human target confidence maps.
α
β
AP
AP50
AP75
AR
0.5
0
50.7
78.9
54.6
56.7
0.5
2
46.2
80.6
46.4
52.0
0.5
4
54.8
82.9
58.8
60.4
0.5
6
57.1
84.4
62.4
62.2
0.5
8
56.7
84.4
61.2
62.1
1.0
0
48.7
77.7
52.2
54.1
TABLE VIII : Comparison experiments under different α and β settings.
Fig. 11 : Task alignment deviation under different α and β settings. Red bars denote alignment deviation of box-driven models, where positive samples are assigned based on box localization. Blue bars represent alignment deviation of ER-Pose-n architecture.
Fig. 12 : Scatter Plot of TAE vs. AP
Fig. 13 : Comparison of task alignment, illustrating effects of keypoint-driven assignment on sample selection.
Loss
ER-Pose-n
ER-Pose-s
ER-Pose-m
AP
AR
AP
AR
AP
AR
Lap
55.7
60.6
62.2
67.2
68.9
73.0
Gau(OKS)
56.1
61.4
65.3
70.1
69.1
73.3
SOKS
57.1
61.6
65.8
70.2
69.7
73.8
TABLE IX : Performance evaluation under different loss functions.
model
Backbone
Input size
Params(M)
AP
AP50
AP75
APE
APM
APH
SimpleBaseline [ 22 ]
ResNet-101
256 × 192
34.0
60.8
81.4
65.7
71.4
61.2
51.2
DEKR [ 22 ]
HRNet-W32
512 × 512
65.7
67.3
86.4
72.2
74.6
68.1
58.7
CID [ 47 ]
HRNet-W32
512 × 512
29.4
71.2
89.8
76.7
77.9
71.9
63.8
HigherHRNet [ 21 ]
HRNet-W32
512 × 512
63.8
65.9
86.4
70.6
73.3
66.5
57.9
YOLO-Pose-s [ 6 ]
CSPDarknet
640 × 640
11.6
61.9
87.6
67.8
69.3
62.5
53.9
YOLO-Pose-m [ 6 ]
CSPDarknet
640 × 640
26.4
66.6
89.4
73.7
73.8
67.3
58.8
TABLE X : Evaluation on Crowdpose
Fig. 14 : Visualization comparison of ER-Pose and advanced regression methods on partial images of CrowdPose. (a) YOLO-Pose-s test results. (b) KAPAO-s test results. (c) ER-Pose-s test results. ER-Pose can better localize humans in complex and occluded scenes, and can achieve better accuracy.
Setting
Dataset
YOLO-Pose-n
ER-POSE-n
ΔAP
From scratch
COCO
47.5
50.7
+3.2
Pretrained
COCO
50.4
57.1
+6.7
From scratch
CrowdPose
45.5
52.9
+7.4
Pretrained
CrowdPose
53.4
58.3
+4.9
Pretrained(COCO)
OCHuman
30.7
37.1
+6.4
TABLE XI : Comparison of AP with and without pretraining on COCO, CrowdPose, and OCHuman, relative to baseline YOLO-Pose.
Fig. 15 : Visualization examples of ER-Pose-n predictions across diverse scenarios.
ASELSAN, Aerospace Technologies, Türkiye · Istanbul Technical University, Department of Computer Engineering, Türkiye · New York University Abu Dhabi, Division of Engineering, UAE