Abstract

This paper presents practical methods for the sequential generation or simulation of a Gaussian two-dimensional random field. The specific realizations typically correspond to geospatial errors or perturbations over a horizontal plane or grid. The errors are either scalar, such as vertical errors, or multivariate, such as , , and errors. These realizations enable simulation-based performance assessment and tuning of various geospatial applications. Both homogeneous and non-homogeneous random fields are addressed. The sequential generation is very fast and compared to methods based on Cholesky decomposition of an a priori covariance matrix and Sequential Gaussian Simulation. The multi-grid point covariance matrix is also developed for all the above random fields, essential for the optimal performance of many geospatial applications ingesting data with these types of errors.

Highlights

  • Introduction and MotivationThis paper identifies a specific and practical subclass of homogeneous Gaussian two-dimensional (2D) random fields and presents a simple, fast, sequential method to generate discrete realizations over a grid for the purpose of Monte Carlo simulation-based analyses

  • Fast Sequential Simulation (FSS) was derived independently, it is demonstrated a special case of Sequential Gaussian Simulation which is commonly used in the Geostatistics community

  • We present FSS, the algorithm for the fast and sequential generation of a discrete and specific realization of this random field that can be used for various Monte Carlo simulation-based analyses

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Summary

Introduction and Motivation

This paper identifies a specific and practical subclass of homogeneous Gaussian two-dimensional (2D) random fields and presents a simple, fast, sequential method to generate discrete realizations over a (horizontal) grid for the purpose of Monte Carlo simulation-based analyses. The paper generalizes FSS results even further to non-homogeneous Gaussian two-dimensional random fields, where the variance and spatial correlations are a function of grid location. FSS is directly related to both generalized multi-grid point covariance matrices [6] and strictly positive definite correlation functions [7] that have applications in the Geospatial community.

A Scalar Gaussian 2D Random Field and Its Sequential Generation
Core Grid-Generation Equation
Sequential Generation Algorithm for Realization over a pxq Grid
Grid Spacing
Grid Buffer
Example Realizations
Multi-Grid Point Covariance Matrix
Interpolation into the Grid
Comparison to Alternate Generation Methods
Timing Comparisons among Simulation Techniques
Discussion of Timing Results
Extension of FSS to a Multivariate Gaussian 2D Random Field
Common Spatial Correlation Subcase
Diagonal Covariance Subcase
General Case with Constraint Enforced
Extension of FSS to a Non-Homogeneous 2D Random Field
Method 1
Typical Statistics
Method 2
Summary and Conclusions
Relationship of Core Grid-Generation Equation with Underlying Random Samples
Findings
Proof of Relationship
Derivation of Statistics

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