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Optimal Sensor Placement in Gaussian Processes via Column Subset Selection

Jessie Chen, Hangjie Ji, Arvind K. Saibaba

TL;DR

This work addresses optimal sensor placement for Gaussian process regression when only a limited number of sensors can be deployed. It recasts the problem as a column subset selection task on the GP covariance matrix and develops a conceptual Golub-Klema-Stewart (GKS) framework to achieve near-optimal D-optimal designs, complemented by Nyström-based approximations (NysGKS) to scale to large candidate sets. The authors also introduce pivoted Cholesky variants and greedy baselines, providing theoretical bounds on D-optimality and eigenvalue behavior under Nyström approximations, and validate the approaches on thin liquid film dynamics and sea surface temperature data, showing favorable performance and uncertainty-aware reconstructions. Overall, the paper delivers scalable, mathematically grounded sensor-placement algorithms with competitive accuracy and robust uncertainty quantification for GP-based surrogate modeling. The methods are particularly appealing for large-scale geophysical and engineering applications where data collection is costly or impractical.

Abstract

Gaussian process regression uses data measured at sensor locations to reconstruct a spatially dependent function with quantified uncertainty. However, if only a limited number of sensors can be deployed, it is important to determine how to optimally place the sensors to minimize a measure of the uncertainty in the reconstruction. We consider the Bayesian D-optimal criterion to determine the optimal sensor locations by choosing sensors from a candidate set of sensors. Since this is an NP-hard problem, our approach models sensor placement as a column subset selection problem (CSSP) on the covariance matrix, computed using the kernel function on the candidate sensor points. We propose an algorithm that uses the Golub-Klema-Stewart framework (GKS) to select sensors and provide an analysis of lower bounds on the D-optimality of these sensor placements. To reduce the computational cost in the GKS step, we propose and analyze algorithms for the D-optimal sensor placements using Nyström approximations on the covariance matrix. Moreover, we propose several algorithms that select sensors via Nyström approximation of the covariance matrix, utilizing the randomized Nyström approximation, random pivoted Cholesky and greedy pivoted Cholesky. We demonstrate the performance of our method on two applications: thin liquid film dynamics and sea surface temperature.

Optimal Sensor Placement in Gaussian Processes via Column Subset Selection

TL;DR

This work addresses optimal sensor placement for Gaussian process regression when only a limited number of sensors can be deployed. It recasts the problem as a column subset selection task on the GP covariance matrix and develops a conceptual Golub-Klema-Stewart (GKS) framework to achieve near-optimal D-optimal designs, complemented by Nyström-based approximations (NysGKS) to scale to large candidate sets. The authors also introduce pivoted Cholesky variants and greedy baselines, providing theoretical bounds on D-optimality and eigenvalue behavior under Nyström approximations, and validate the approaches on thin liquid film dynamics and sea surface temperature data, showing favorable performance and uncertainty-aware reconstructions. Overall, the paper delivers scalable, mathematically grounded sensor-placement algorithms with competitive accuracy and robust uncertainty quantification for GP-based surrogate modeling. The methods are particularly appealing for large-scale geophysical and engineering applications where data collection is costly or impractical.

Abstract

Gaussian process regression uses data measured at sensor locations to reconstruct a spatially dependent function with quantified uncertainty. However, if only a limited number of sensors can be deployed, it is important to determine how to optimally place the sensors to minimize a measure of the uncertainty in the reconstruction. We consider the Bayesian D-optimal criterion to determine the optimal sensor locations by choosing sensors from a candidate set of sensors. Since this is an NP-hard problem, our approach models sensor placement as a column subset selection problem (CSSP) on the covariance matrix, computed using the kernel function on the candidate sensor points. We propose an algorithm that uses the Golub-Klema-Stewart framework (GKS) to select sensors and provide an analysis of lower bounds on the D-optimality of these sensor placements. To reduce the computational cost in the GKS step, we propose and analyze algorithms for the D-optimal sensor placements using Nyström approximations on the covariance matrix. Moreover, we propose several algorithms that select sensors via Nyström approximation of the covariance matrix, utilizing the randomized Nyström approximation, random pivoted Cholesky and greedy pivoted Cholesky. We demonstrate the performance of our method on two applications: thin liquid film dynamics and sea surface temperature.
Paper Structure (57 sections, 9 theorems, 72 equations, 15 figures, 3 tables, 3 algorithms)

This paper contains 57 sections, 9 theorems, 72 equations, 15 figures, 3 tables, 3 algorithms.

Key Result

Theorem 1

For any selection matrix $\mathbf{S} \in \mathbb{R}^{n \times k}$ such that $\mathrm{rank}(\mathbf{V}_k^\top \mathbf{S})=k$, where $\mathbf{\Lambda}_k$ are the dominant eigenvalues as in decomp and $\mathbf{S}_{opt} \in \mathbb{R}^{n \times k}$ is the selection operator that selects columns of $\mathbf{K}$ which achieve maximal D-optimality.

Figures (15)

  • Figure 1: Schematic representation of the workflow in our proposed method to selecting D-optimal sensors in GPs. The red dots represent the sensors placed by the GKS algorithm on the covariance matrix $\mathbf{K}$.
  • Figure 2: (Left) GP regression in the dashed red line and sensor selection in red asterisks using the conceptual GKS (\ref{['alg:cssp']}). Reconstruction of the function is at $t=140$. The sensor selection achieves a D-optimality score of 221.39. The relative error \ref{['relerr']} in the reconstructed droplet profile is 0.0025. (Right) Conceptual GKS (\ref{['alg:cssp']}), efficient greedy chen2018fast, rank $k+10$ NysGKS (\ref{['alg:nys']}), and rank $k$ RPCholesky and greedy pivoted Cholesky (\ref{['alg:cholgks']}) compared with 10,000 realizations of random sensor placement in terms of D-optimality.
  • Figure 3: Comparisons of the height of the droplet over the entire domain in time and space for the true profile, GKS-selected sensor reconstruction (first column) and its error (second column), and Greedy-selected sensor reconstruction and its error. The black horizontal lines represent the sensor selections for each respective algorithm.
  • Figure 4: True Sea Surface Temperature for the week of February 4, 2018.
  • Figure 5: GP mean prediction (left) and variance (right) plot using the NysGKS (\ref{['alg:nys']}). Selected sensor locations are indicated by red asterisks.
  • ...and 10 more figures

Theorems & Definitions (20)

  • Theorem 1
  • proof
  • Corollary 1
  • proof
  • Theorem 2
  • proof
  • Theorem 3
  • proof
  • Theorem 4
  • proof
  • ...and 10 more