Inductive spatio-temporal kriging infers signals at unobserved locations from observed sensors, but real-world observations are often incomplete and exhibit block-wise missingness caused by failures, interruptions, or maintenance. A common impute-then-krige pipeline suffers from objective mismatch: better reconstruction on observed sensors does not necessarily improve downstream kriging, and value-dependent imputation bias can be propagated to unobserved nodes. We propose UniSTOK, a plug-and-play framework for inductive spatio-temporal kriging under incomplete observations. We first introduce Reliability-guided Signal Regulation (RSR), which estimates entry-wise reliability from temporal continuity and spatial support, and uses it to regulate the input signals so that reliable observations are emphasized while long-gap or weakly supported entries are suppressed before spatial propagation. We further introduce Residual Bias Calibration (RBC), which estimates value-conditioned residual prototypes after the main predictor converges and learns context-correction amplitudes to adaptively calibrate systematic over- or under-estimation in final kriging predictions. Extensive experiments on real-world datasets show that UniSTOK consistently improves multiple kriging backbones.
Figures & tables
Figure 1: Overview of the studied setting, key challenge, and proposed solution.
Figure 2: Overview of UniStok , which consists of three components: Reliability-guided Signal Regulation (RSR), the shared-backbone main predictor, and Residual Bias Calibration (RBC).
Models
METR-LA
PEMS-BAY
NREL-AL
Avg. Improv.(%)
MAE
RMSE
MAPE
MAE
RMSE
MAPE
MAE
RMSE
DCRNN ICLR’18
Base
6.20
9.89
17.30
3.70
6.76
8.86
2.11
4.23
–
+Ours
5.93 ↓ 4.4
9.48 ↓ 4.1
16.34 ↓ 5.5
3.50 ↓ 5.4
6.70 ↓ 0.9
8.71 ↓ 1.7
2.08 ↓ 1.4
4.06 ↓ 4.0
3.4
STGCN IJCAI’18
Base
6.28
10.36
17.42
3.68
6.62
8.72
2.25
4.34
–
+Ours
5.76 ↓ 8.3
9.40 ↓ 9.3
16.30 ↓ 6.4
3.40 ↓ 7.6
6.59 ↓ 0.5
8.43 ↓ 3.3
1.97 ↓ 12.4
3.85 ↓ 11.3
7.4
GMAN AAAI’20
Base
6.44
11.27
17.98
4.01
7.58
9.12
1.71
3.24
–
Table 1: Performance comparison of plug-in enhancement across backbones and datasets. Lower is better. Gray : base model results; Black : results with our plug-in ( +Ours ). ↓ x : relative improvement (%) of +Ours over Base.
Model
METR-LA
PEMS-BAY
NREL-AL
ImputeFormer+STA-GANN
MAE
6.04±0.15
3.84±0.05
1.91±0.05
RMSE
9.34±0.23
6.76±0.09
3.95±0.19
MAPE
18.11±0.88
9.14±0.05
–
UniStok
MAE
5.84 ± 0.05
3.37 ± 0.00
1.76 ± 0.01
RMSE
9.22 ± 0.05
6.09 ± 0.03
3.41 ± 0.03
MAPE
16.86 ± 0.13
8.32 ± 0.04
–
Table 2: Comparison with a two-stage pre-imputation pipeline.
Figure 3: Ablation study of the core modules on three datasets. Full denotes the complete UniStok framework; w/o RSR removes reliability-guide signal regulation; w/o RBC removes residual bias calibration; Original denotes the backbone without our framework.
Figure 4: Hyperparameter sensitivity of UniStok with IGNNK on METR-LA, varying the number of residual bins K , the residual correction bound η , and the reliability regulation strength α .
Figure 5: Parameter–accuracy trade-off on METR-LA. Empty and filled circles denote base backbones and their UniStok -enhanced variants, respectively.
Appendix figures & tables14 assets
Supplementary material from the paper’s appendix.
Appendix
Notation
Definition
Data & Task
G=(V,E)
Sensor graph with node set V and edge set E
Vo / Vu
Observed / unobserved node sets, with ∣Vo∣=N and ∣Vu∣=U
X∈RN×T
Historical measurements at observed nodes over the full time horizon
Y∈RU×T
Ground-truth signals at unobserved nodes
A∈[0,1](N+U)×(N+U)
Weighted adjacency matrix of the whole sensor graph
Appendix
Table 3: Notations used in UniStok .
Figure 6: Relative MAE degradation under random and block missingness.
Figure 7: Stage-1 imputation MAE on observed sensors under block missingness.
Dataset
Backbone
Best Method
Best MAE
Worst Method
Worst MAE
METR-LA
IGNNK
Linear
6.230
KNN
6.434
KITS
Zero
6.548
ImputeFormer
6.781
STGCN
Zero
6.340
Mean
6.545
STA-GANN
Zero
6.229
ImputeFormer
6.641
DARKFARSEER
Mean
6.375
Zero
6.793
INCREASE-SP
SAITS
6.201
Zero
6.392
Appendix
Table 4: Stage-2 kriging performance of the imputation-first pipeline under block missingness. We report the best and worst imputation method for each dataset-backbone pair.
Figure 8: Comparison between Stage-1 reconstruction ranking and Stage-2 kriging ranking. For each dataset, rows list the imputation methods ordered by reconstruction MAE, and each cell shows the downstream kriging rank under a specific ISK backbone.
Method
GME
MAE
Low CB
Mid CB
High CB
Zero
+0.37
9.92
+15.33
-4.81
-9.40
Mean
-0.18
7.74
+9.60
-4.51
-5.63
Linear
-0.38
8.08
+7.49
-4.25
-4.38
KNN
+0.67
7.84
+9.28
-2.05
-5.21
GRIN
+1.80
5.51
+7.97
-0.40
-2.17
SAITS
+1.38
4.80
+7.08
-1.04
-1.89
Appendix
Table 5: Stage-1 imputation bias on simulated missing entries of observed nodes. Positive values indicate overestimation, and negative values indicate underestimation.
Backbone
Setting
GME
Low-value CB
High-value CB
DARKFARSEER
No missing
2.10
6.85
-2.10
Imputation
[4.40, 4.60]
[12.16, 13.42]
[-4.25, -4.12]
IGNNK
No missing
1.20
5.35
-1.85
Imputation
[2.49, 2.86]
[11.57, 12.20]
[-3.72, -3.42]
INCREASE-SP
No missing
1.35
5.80
-1.90
Imputation
[2.47, 2.81]
[10.94, 12.39]
[-3.85, -3.40]
Appendix
Table 6: Kriging bias under the no-missing reference and block-wise incomplete observations. The no-missing setting uses original observed values without imputation, while the imputation setting reports the range across seven imputation methods. Positive values indicate overestimation, and negative values indicate underestimation.
Models
METR-LA
PEMS-BAY
NREL-AL
Avg. Improv.(%)
MAE
RMSE
MAPE
MAE
RMSE
MAPE
MAE
RMSE
DCRNN ICLR’18
Base
6.03
9.51
17.09
3.58
6.64
8.75
1.98
3.87
–
+Ours
5.82 ↓ 3.5
9.44 ↓ 0.7
16.21 ↓ 5.1
3.41 ↓ 4.7
6.57 ↓ 1.1
8.35 ↓ 4.6
1.76 ↓ 11.1
3.25 ↓ 16.0
5.9
STGCN IJCAI’18
Base
6.04
9.65
17.32
3.59
6.70
8.83
2.01
3.93
–
+Ours
5.72 ↓ 5.3
9.34 ↓ 3.2
16.20 ↓ 6.5
3.34 ↓ 7.0
6.46 ↓ 3.6
8.22 ↓ 6.9
1.66 ↓ 17.4
3.30 ↓ 16.0
8.2
GMAN AAAI’20
Base
6.37
11.10
17.62
3.92
7.34
8.99
1.69
3.13
–
Appendix
Table 7: Performance comparison under random missingness across backbones and datasets. Lower is better. Gray : base model results; Black : results with our plug-in ( +Ours ). ↓ x : relative improvement (%) of +Ours over Base.
Models
METR-LA
PEMS-BAY
NREL-AL
Avg. Improv.(%)
MAE
RMSE
MAPE
MAE
RMSE
MAPE
MAE
RMSE
DCRNN ICLR’18
Base
6.01
9.47
17.02
3.54
6.61
8.67
1.90
3.72
–
+Ours
5.75 ↓ 4.3
9.42 ↓ 0.5
16.13 ↓ 5.2
3.38 ↓ 4.5
6.53 ↓ 1.2
8.36 ↓ 3.6
1.74 ↓ 8.4
3.24 ↓ 12.9
5.1
STGCN IJCAI’18
Base
6.07
9.63
17.29
3.59
6.71
8.86
1.93
3.88
–
+Ours
5.69 ↓ 6.3
9.26 ↓ 3.8
16.11 ↓ 6.8
3.32 ↓ 7.5
6.44 ↓ 4.0
8.13 ↓ 8.2
1.62 ↓ 16.1
3.29 ↓ 15.2
8.5
GMAN AAAI’20
Base
6.32
10.74
17.55
3.94
7.40
8.95
1.65
3.08
–
Appendix
Table 8: Performance comparison under the no-missing setting across backbones and datasets. Lower is better. Gray : base model results; Black : results with our plug-in ( +Ours ). ↓ x : relative improvement (%) of +Ours over Base.
Metric
Setting
DCRNN
STGCN
GMAN
IGNNK
SATCN
INCREASE
KITS
STA-GANN
DarkFarseer
MAE
Base
74.23
78.52
97.37
78.55
79.36
76.28
85.09
76.07
99.23
+Ours
72.60 ↓ 2.2
76.99 ↓ 1.9
93.12 ↓ 4.4
77.60 ↓ 1.2
78.27 ↓ 1.4
74.85 ↓ 1.9
78.16 ↓ 8.1
75.85 ↓ 0.3
97.86 ↓ 1.4
RMSE
Base
112.59
114.85
143.81
115.29
115.38
115.37
130.74
113.17
146.18
+Ours
111.46 ↓ 1.0
113.40 ↓ 1.3
138.04 ↓ 4.0
114.50 ↓ 0.7
113.96 ↓ 1.2
110.71 ↓ 4.0
117.22 ↓ 10.3
110.63 ↓ 2.2
143.67 ↓ 1.7
Appendix
Table 9: Performance comparison on NZ-Highway with naturally occurring block-wise missing observations. Lower is better. Gray : base model results; Black : results with our plug-in ( +Ours ). ↓ x : relative improvement (%) of +Ours over Base.
Figure 9: Module-level ablation results based on the average relative degradation over the full model. The RSR variants include w/o temporal reliability , w/o spatial reliability , and w/o residual compensation . The fusion variants include regulated-only , M as second branch , and w/o gate . The RBC variants include w/o context amplitude , w/o bin-balanced loss , and hard-bin RBC .
Figure 10: Additional hyperparameter sensitivity results of UniStok with IGNNK as the backbone. We analyze the number of residual bins K in RBC, the residual correction bound η , and the reliability regulation strength α in RSR. Lower MAE and RMSE indicate better performance.
Figure 11: Additional visualization of RSR and adaptive fusion on four representative samples. Each column corresponds to one sample. From top to bottom, the three rows show the observation mask M , the RSR-induced input difference X−X , and the adaptive fusion gate G . Larger G indicates stronger reliance on the RSR-enhanced branch.
Figure 12: From left to right: ground-truth values, predictions before RBC, predictions after RBC, and learned correction amplitudes.
Residual error propagation remains a fundamental problem in recurrent models, where small prediction inaccuracies compound over time and degrade long-horizon performance. Accurately modeling the correlation structure of such residuals is critical for reliable uncertainty quantification in probabilistic multivariate timeseries forecasting. While recent time-series deep models efficiently parametrize time-varying contemporaneous correlations, they often assume temporal independence of errors and neglect spatial correlation across the observed network. In this paper, we introduce Teger, a structured uncertainty module that overcomes the spa- tial and temporal limitations of error-correlated autoregressive forecasting. Teger proposes a spatial curvature-aware graph rewiring mechanism explicitly strengthening information-bottleneck edges identified by discrete Forman curvature. The component is integrated into a low-rank-plus-diagonal covariance head, preserving tractable inference via the Woodbury identity. Teger is backbone-agnostic, requiring only the latent state produced by any autoregressive encoder. We provide theoretical evidence of Teger, and experimentally evaluate it on LSTM, Transformer, and xLSTM backbones across four real-world spatio-temporal datasets, showing consistent improvement in Continuous Ranked Probability Score (CRPS). We further provide a formal theoretical analysis connecting curvature-aware rewiring to (i) oversquashing alleviation, (ii) improved spectral connectivity, (iii) reduced effective resistance, and (iv) improved covariance calibration bounds
Seyed Mohamad Moghadas, Esther Rodrigo Bonet, Bruno Cornelis +1
Spatiotemporal prediction aims to learn discriminative representations from correlated temporal signals over spatial structures for accurate future inference. A central challenge is spatial indistinguishability: different nodes may share similar historical patterns yet evolve toward divergent futures, severely degrading forecasting performance in real-world sensor networks. Existing embedding-based and graph neural network (GNN)-based approaches can partially detect such ambiguous nodes but rely on historical similarity, struggling to capture future behavioral divergence. We propose STOT (SpatioTemporal Optimal Transport), a self-supervised framework that resolves spatiotemporal ambiguity via structured masking guided by optimal transport. Our key idea treats indistinguishability as a disambiguation problem: future states are inferred by exploiting concurrent spatial correlations and their time-varying similarity. We design a similarity-aware metric for dynamic inter-node relationships and an optimal transport-based masking strategy to emphasize ambiguous positions during pre-training. A batch consistency constraint preserves semantic coherence, while a random-walk masking mechanism promotes structured context exploration. Experiments on six real-world datasets show that STOT performs competitively with state-of-the-art baselines on the evaluated benchmarks and improved interpretability through transport-plan visualizations.
Guangyu Wang, Jiawei Tong
Data Science and Artificial Intelligence, Dongbei University of Finance and Economics, Dalian, Liaoning, China · Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Liverpool, United Kingdom
Real-world spatio-temporal forecasting must handle irregular time points, spatially sparse observations, and the need for uncertainty quantification. This setting is often further compounded by nonlocal interactions (long-range spatial coupling). Modeling continuous-space, continuous-time nonlocal dynamics naturally leads to infinite-dimensional integro-differential equations (IDEs), making principled Bayesian inference intractable. We propose the NonLocal Bayesian Spatio-Temporal model (NLBST), a hierarchical Bayesian framework for continuous spatio-temporal fields that learns explicit nonlocal coupling while retaining tractable inference. NLBST represents the latent field via a coordinate-based spatial basis expansion and models the coefficient process with a continuous-time ODE whose learnable linear operator corresponds to a Galerkin reduction of a nonlocal IDE; a Neural ODE residual captures additional nonlinear dynamics. A linear-Gaussian observation model enables Kalman-style sequential updates under missing and irregular observations, while the spatial basis representation enables inductive prediction at unmeasured locations without retraining. Global parameters are learned via variational inference, and uncertainty is handled through a Bayesian hierarchy. Experiments on synthetic and real-world datasets demonstrate strong forecasting and spatial generalization with well-calibrated uncertainty, yielding substantial gains over baselines in strongly nonlocal and partially observed regimes.
Jaeyeong Lee, Heeyoung Kim
Department of Industrial and Systems Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea