Semantic segmentation networks operate on a fixed set of classes and therefore fail when out-of-distribution (OOD) objects appear during deployment, a critical limitation for safety-critical applications such as autonomous driving. Reliably identifying OOD objects requires well-calibrated epistemic uncertainty, yet common softmax-based confidence scores remain overconfident, while Bayesian alternatives such as Monte Carlo dropout or deep ensembles require costly repeated forward passes. Evidential Deep Learning (EDL) offers an efficient alternative by modeling class probabilities as a Dirichlet distribution learned from a single deterministic forward pass. Existing EDL formulations rely on Euclidean objectives that push predictions towards the simplex vertices, encouraging overconfidence rather than preserving uncertainty for unfamiliar inputs. We instead employ Wasserstein-based objectives, which respect the geometry of the probability simplex, and study the influence of the Wasserstein order on segmentation accuracy and OOD detection within a unified evidential framework. We evaluate this framework on a convolutional (DeepLabV3+) and a transformer-based (SegFormer) architecture on the SegmentMeIfYouCan benchmark, including LostAndFound, RoadObstacle21, RoadAnomaly21, and Fishyscapes. Our results show the optimal Wasserstein order is architecture-dependent: second-order objectives dominate on the convolutional backbone, third-order objectives on the transformer backbone, and our framework surpasses comparable baselines on most metrics, with a single deterministic forward pass.
Figures & tables
Figure 1: Top: Semantic segmentation by a deep neural network. Bottom: Evidential uncertainty heatmap obtained by our method. Brighter colors correspond to higher uncertainty.
Figure 2: Illustration of probability mass transport for support extension.
Figure 3: Illustration of the MSE effect on the probability simplex.
Figure 4: Illustration of the Wasserstein effect on the probability simplex.
Figure 5: Left: Semantic segmentation prediction. Right: OOD heatmap obtained by our method using DeeplabV3+, W2 , 0.45 MSE and 0.75 Dice. The top images are from the LostAndFound dataset (a kid playing on the street next to a pile of rubble) and the bottom images from RoadAnomaly21 (a car with an attached caravan).
LostAndFound test-NoKnown
RoadObstacle21
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
Ensemble
2.9
82.0
6.7
7.6
2.7
1.1
77.2
8.6
4.7
1.3
MC Dropout
36.8
35.6
17.4
34.7
13.0
4.9
50.3
5.5
5.8
1.1
Maximum Softmax
30.1
33.2
14.2
62.2
10.3
15.7
16.6
19.7
15.9
6.3
Entropy
47.1
21.6
30.7
42.1
30.2
28.4
26.7
14.7
20.5
9.7
PGN
69.3
9.8
50.0
44.8
45.4
16.5
19.7
19.5
14.8
7.4
Table 1: OOD segmentation benchmark results for the LostAndFound and RoadObstacle21 dataset.
Fishyscapes LostAndFound
RoadAnomaly21
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
Ensemble
0.3
90.4
3.1
1.1
0.4
17.7
91.1
16.4
20.8
3.4
MC Dropout
14.4
47.8
4.8
18.1
4.3
28.9
69.5
20.5
17.3
4.3
Maximum Softmax
5.6
40.5
3.5
9.5
1.8
28.0
72.1
15.5
15.3
5.4
Entropy
15.8
36.1
7.5
16.3
8.6
30.0
73.0
17.8
15.6
5.1
PGN
26.9
36.6
14.8
29.6
16.5
42.8
56.4
25.8
21.8
9.7
Table 2: OOD segmentation benchmark results for the Fishyscapes LostAndFound and RoadAnomaly21 dataset.
DeepLabV3+
SegFormer
Baseline
80.09
84.00
W1
67.67−15.55+9.43
80.61−0.24+0.27
W2
56.14−5.01+6.53
80.60−0.44+0.38
W3
66.88−11.04+9.46
80.54−0.36+0.20
Table 3: In-distribution evaluation on the Cityscapes dataset using mIoU. The rows correspond to the three Wasserstein orders W1 , W2 , and W3 , and the two columns to the DeepLabV3+ and SegFormer backbones. +a and −b describe the size to the largest and smallest deviation respectively.
Appendix figures & tables12 assets
Supplementary material from the paper’s appendix.
Appendix
LostAndFound test-NoKnown
RoadObstacle21
λW1
λDice
λKL
λMSE
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
0.00
0.00
0.00
1.00
25.7
56.8
25.9
27.7
14.6
1.6
62.1
18.5
5.6
2.0
1.00
0.00
0.00
0.00
47.5
27.4
21.5
39.2
19.7
4.1
66.0
6.9
8.5
2.0
1.00
0.00
0.00
0.40
50.4
25.8
21.2
38.0
19.2
30.7
42.3
11.6
26.4
8.7
1.00
0.00
0.00
0.45
53.2
23.2
25.3
37.7
20.7
20.2
31.2
11.0
18.3
5.8
1.00
0.00
0.00
0.50
44.4
30.5
25.2
42.8
23.6
12.2
32.6
3.6
34.0
3.4
Appendix
Table A.1: OOD segmentation results for LostAndFound and RoadObstacle21 using DeepLabV3+ with Wasserstein order W1 .
LostAndFound test-NoKnown
RoadObstacle21
λW2
λDice
λKL
λMSE
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
0.00
0.00
0.00
1.00
25.7
56.8
25.9
27.7
14.6
1.6
62.1
18.5
5.6
2.0
1.00
0.00
0.00
0.00
43.8
38.9
18.9
53.9
21.6
1.1
44.5
14.1
3.6
1.7
1.00
0.00
0.00
0.40
50.4
36.9
18.2
45.3
20.3
13.7
53.9
8.0
15.2
3.3
1.00
0.00
0.00
0.45
46.1
47.6
22.7
53.2
26.3
13.5
40.9
7.2
20.6
4.4
1.00
0.00
0.00
0.45
48.8
38.9
17.0
44.4
18.4
17.2
49.9
6.4
13.7
3.0
Appendix
Table A.2: OOD segmentation results for LostAndFound and RoadObstacle21using DeepLabV3+ with Wasserstein order W2 .
LostAndFound test-NoKnown
RoadObstacle21
λW3
λDice
λKL
λMSE
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
0.00
0.00
0.00
1.00
25.7
56.8
25.9
27.7
14.6
1.6
62.1
18.5
5.6
2.0
1.00
0.00
0.00
0.00
34.0
88.1
13.8
40.1
17.0
12.0
74.1
8.4
18.6
5.2
1.00
0.00
0.00
0.40
10.5
93.2
1.3
12.0
1.2
13.7
50.6
4.7
19.3
3.8
1.00
0.00
0.00
0.45
12.6
89.5
8.4
23.5
8.0
2.8
63.1
5.0
6.4
1.9
1.00
0.00
0.00
0.50
11.7
84.9
2.1
10.6
1.6
5.4
73.7
2.9
6.0
1.4
Appendix
Table A.3: OOD segmentation results for LostAndFound and RoadObstacle21using DeepLabV3+ with Wasserstein order W3 .
Fishyscapes LostAndFound
RoadAnomaly21
λW1
λDice
λKL
λMSE
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
0.00
0.00
0.00
1.00
25.7
56.8
25.9
27.7
14.6
1.6
62.1
18.5
5.6
2.0
1.00
0.00
0.00
0.00
47.5
27.4
21.5
39.2
19.7
4.1
66.0
6.9
8.5
2.0
1.00
0.00
0.00
0.40
50.4
25.8
21.2
38.0
19.2
30.7
42.3
11.6
26.4
8.7
1.00
0.00
0.00
0.45
53.2
23.2
25.3
37.7
20.7
20.2
31.2
11.0
18.3
5.8
1.00
0.00
0.00
0.50
44.4
30.5
25.2
42.8
23.6
12.2
32.6
3.6
34.0
3.4
Appendix
Table A.4: OOD segmentation results for Fishyscapes and RoadAnomaly21 using DeepLabV3+ with Wasserstein order W1 .
Fishyscapes LostAndFound
RoadAnomaly21
λW2
λDice
λKL
λMSE
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
0.00
0.00
0.00
1.00
25.7
56.8
25.9
27.7
14.6
1.6
62.1
18.5
5.6
2.0
1.00
0.00
0.00
0.00
4.6
53.6
7.1
12.6
9.2
33.0
60.3
21.1
19.5
5.0
1.00
0.00
0.00
0.40
10.1
38.4
4.6
20.8
4.2
50.3
57.9
20.0
22.6
5.6
1.00
0.00
0.00
0.45
2.5
42.0
11.0
11.8
7.3
42.9
59.2
18.9
23.5
6.0
1.00
0.00
0.00
0.50
3.9
46.5
8.5
10.4
6.9
35.6
65.2
23.4
20.3
6.8
Appendix
Table A.5: OOD segmentation results for Fishyscapes and RoadAnomaly21 using DeepLabV3+ with Wasserstein order W2 .
Fishyscapes LostAndFound
RoadAnomaly21
λW3
λDice
λKL
λMSE
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
0.00
0.00
0.00
1.00
25.7
56.8
25.9
27.7
14.6
1.6
62.1
18.5
5.6
2.0
1.00
0.00
0.00
0.00
7.7
53.3
6.2
23.6
20.7
36.0
85.0
16.5
23.8
6.5
1.00
0.00
0.00
0.40
2.7
68.3
1.6
13.3
2.4
40.6
67.2
17.0
26.8
6.3
1.00
0.00
0.00
0.45
2.2
54.6
8.9
9.7
7.8
42.3
76.8
20.7
25.5
7.4
1.00
0.00
0.00
0.50
2.3
52.5
5.8
10.8
4.7
40.2
76.3
15.2
28.3
6.0
Appendix
Table A.6: OOD segmentation results for Fishyscapes and RoadAnomaly21 using DeepLabV3+ with Wasserstein order W3 .
LostAndFound test-NoKnown
RoadObstacle21
λW1
λDice
λKL
λMSE
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
0.00
0.00
0.00
1.00
22.4
63.1
7.0
13.1
26.9
21.2
64.7
4.2
55.7
3.9
1.00
0.00
0.00
0.00
16.1
57.7
4.5
11.6
1.3
8.9
66.1
3.0
13.6
0.8
1.00
0.00
0.00
0.40
41.9
43.9
23.3
25.5
13.1
29.1
48.6
13.0
20.9
5.2
1.00
0.00
0.00
0.45
34.1
39.8
22.4
19.2
9.7
31.5
35.8
9.8
28.6
5.8
1.00
0.00
0.00
0.50
34.1
49.8
16.7
23.8
9.2
24.3
39.0
11.0
13.8
3.0
Appendix
Table A.7: OOD segmentation results for LostAndFound and RoadObstacle21 using SegFormer with Wasserstein order W1 .
LostAndFound test-NoKnown
RoadObstacle21
λW2
λDice
λKL
λMSE
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
0.00
0.00
0.00
1.00
22.4
63.1
7.0
13.1
26.9
21.2
64.7
4.2
55.7
3.9
1.00
0.00
0.00
0.00
23.2
65.7
10.3
12.8
3.7
15.1
46.5
3.3
24.3
1.5
1.00
0.00
0.00
0.40
21.0
62.9
7.3
14.6
2.9
18.9
67.9
7.7
11.6
2.2
1.00
0.00
0.00
0.45
8.8
79.9
3.2
8.1
0.9
9.4
81.0
3.0
40.9
2.7
1.00
0.00
0.00
0.50
34.8
62.9
17.8
20.5
9.1
27.7
54.7
10.0
24.6
4.7
Appendix
Table A.8: OOD segmentation results for LostAndFound and RoadObstacle21 using SegFormer with Wasserstein order W2 .
LostAndFound test-NoKnown
RoadObstacle21
λW3
λDice
λKL
λMSE
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
0.00
0.00
0.00
1.00
22.4
63.1
7.0
13.1
26.9
21.2
64.7
4.2
55.7
3.9
1.00
0.00
0.00
0.00
33.0
63.0
13.2
21.6
6.9
20.5
54.1
6.1
27.9
3.4
1.00
0.00
0.00
0.40
38.8
59.7
20.0
30.7
14.1
42.1
57.8
23.3
26.7
11.8
1.00
0.00
0.00
0.45
21.1
64.2
10.1
14.5
4.1
20.9
64.6
10.0
14.8
3.1
1.00
0.00
0.00
0.50
35.5
47.5
18.7
19.3
8.9
29.5
34.6
14.5
24.1
6.8
Appendix
Table A.9: OOD segmentation results for LostAndFound and RoadObstacle21 using SegFormer with Wasserstein order W3 .
Fishyscapes LostAndFound
RoadAnomaly21
λW1
λDice
λKL
λMSE
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
0.00
0.00
0.00
1.00
32.6
70.1
14.4
49.7
14.4
48.2
96.4
30.1
29.5
8.9
1.00
0.00
0.00
0.00
28.9
67.1
8.9
40.3
11.7
49.4
86.6
32.2
27.9
9.9
1.00
0.00
0.00
0.40
50.4
25.8
21.2
38.0
19.2
30.7
42.3
11.6
26.4
8.7
1.00
0.00
0.00
0.45
53.2
23.2
25.3
37.7
20.7
20.2
31.2
11.0
18.3
5.8
1.00
0.00
0.00
0.50
44.4
30.5
25.2
42.8
23.6
12.2
32.6
3.6
34.0
3.4
Appendix
Table A.10: OOD segmentation results for Fishyscapes and RoadAnomaly21 using SegFormer with Wasserstein order W1 .
Fishyscapes LostAndFound
RoadAnomaly21
λW2
λDice
λKL
λMSE
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
0.00
0.00
0.00
1.00
32.6
70.1
14.4
49.7
14.4
48.2
96.4
30.1
29.5
8.9
1.00
0.00
0.00
0.00
28.2
72.2
6.8
32.0
8.1
48.9
85.1
33.5
24.4
8.1
1.00
0.00
0.00
0.40
35.6
55.0
6.9
63.3
11.5
50.3
87.3
31.0
26.9
8.6
1.00
0.00
0.00
0.45
16.2
73.0
2.7
31.0
3.5
44.6
75.0
35.3
26.0
10.6
1.00
0.00
0.00
0.50
36.5
70.5
8.2
53.7
11.9
59.6
79.4
37.8
28.4
12.0
Appendix
Table A.11: OOD segmentation results for Fishyscapes and RoadAnomaly21 using SegFormer with Wasserstein order W2 .
Fishyscapes LostAndFound
RoadAnomaly21
λW3
λDice
λKL
λMSE
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
AuPRC ↑
FPR 95 ↓
sIoU↑
PPV↑
F1↑
0.00
0.00
0.00
1.00
32.6
70.1
14.4
49.7
14.4
48.2
96.4
30.1
29.5
8.9
1.00
0.00
0.00
0.00
28.4
76.0
9.1
49.1
12.2
57.5
84.4
34.3
28.9
10.6
1.00
0.00
0.00
0.40
37.3
71.2
12.7
54.4
18.8
64.5
72.4
35.7
31.7
13.6
1.00
0.00
0.00
0.45
22.4
69.0
8.4
58.5
13.6
42.4
90.1
30.3
26.3
8.3
1.00
0.00
0.00
0.50
38.0
60.3
10.3
66.7
15.5
56.8
85.0
36.6
28.6
11.4
Appendix
Table A.12: OOD segmentation results for Fishyscapes and RoadAnomaly21 using SegFormer with Wasserstein order W3 .
Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau, France. · CIAD, UTBM, Universit´e Marie et Louis Pasteur, France. · U2IS, ENSTA, Institut Polytechnique de Paris, France.
School of Computer Science and Engineering Southeast University Nanjing 210096, China · School of Computing Information Sciences Saint Francis University2026 Hong Kong SAR, China · CityDepartmentUniversityof Computerof Hong KongScience Hong Kong SAR, China