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1. Stochastic modeling of subglacial topography exposes uncertainty in water routing at Jakobshavn Glacier

   https://doi.org/10.1017/jog.2020.84  

   MacKie, Emma J.; Schroeder, Dustin M.; Zuo, Chen; Yin, Zhen; Caers, Jef (February 2021, Journal of Glaciology)

   null (Ed.)

   Abstract Subglacial topography is an important feature in numerous ice-sheet analyses and can drive the routing of water at the bed. Bed topography is primarily measured with ice-penetrating radar. Significant gaps, however, remain in data coverage that require interpolation. Topographic interpolations are typically made with kriging, as well as with mass conservation, where ice flow dynamics are used to constrain bed geometry. However, these techniques generate bed topography that is unrealistically smooth at small scales, which biases subglacial water flowpath models and makes it difficult to rigorously quantify uncertainty in subglacial drainage patterns. To address this challenge, we adapt a geostatistical simulation method with probabilistic modeling to stochastically simulate bed topography such that the interpolated topography retains the spatial statistics of the ice-penetrating radar data. We use this method to simulate subglacial topography using mass conservation topography as a secondary constraint. We apply a water routing model to each of these realizations. Our results show that many of the flowpaths significantly change with each topographic realization, demonstrating that geostatistical simulation can be useful for assessing confidence in subglacial flowpaths. 

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2. Perceived Naturalness of Interpolation Methods for Character Upper Body Animation.

   https://doi.org/10.1007/978-3-030-90439-5_9  

   Xingyu Lei, Nicoletta Adamo-Villani (January 2022, Advances in Visual Computing. ISVC 2021. Lecture Notes in Computer Science)

   We compare the perceived naturalness of character animations generated using three interpolation methods: linear Euler, spherical linear quaternion, and spherical spline quaternion. While previous work focused on the mathematical description of these interpolation types, our work studies the perceptual evaluation of animated upper body character gestures generated using these interpolations. Ninety-seven participants watched 12 animation clips of a character performing four different upper body motions: a beat gesture, a deictic gesture, an iconic gesture, and a metaphoric gesture. Three animation clips were generated for each gesture using the three interpolation methods. The participants rated their naturalness on a 5-point Likert scale. The results showed that animations generated using spherical spline quaternion interpolation were perceived as significantly more natural than those generated using the other two interpolation methods. The findings held true for all subjects regardless of gender and animation experience and across all four gestures. 

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3. Investigating cost-effective single-beam survey configurations for accurate river bathymetry construction

   https://doi.org/10.1016/j.geomorph.2025.109803  

   Liang, Chung-Yuan; Merwade, Venkatesh; Dey, Sayan (August 2025, Geomorphology)

   River bathymetry is needed to accurately simulate river hydrodynamics. River bathymetric data are typically collected through boat-mounted single- or multi-beam echosounder surveys. Detailed bathymetric data from multibeam surveys may exceed the requirements of standard river hydraulic models (1D and 2D). Compared to data-intensive but expensive multibeam surveys, single-beam surveys are cost-effective. Single-beam surveys can sufficiently inform river simulations when coupled with specific preprocessing and interpolation techniques. This study contrasts two survey patterns, including the commonly used but under-studied zigzag surveys, against the traditional cross-sectional surveys. Linear and anisotropic Kriging interpolations, two widely used methods, are applied to construct bathymetry mesh from different survey configurations. Results from this study highlight efficient survey configurations for both cross-sectional and zigzag patterns, balancing accuracy and cost. Notably, zigzag surveys approach the efficacy of cross-sectional surveys when spaced below a certain threshold, but Kriging interpolation shows diminished performance with sparse zigzag surveys. The findings from this study bridge gaps in previous research by offering nuanced comparisons between survey configurations and interpolations. This study offers a comparative analysis to guide more effective planning and utilization of single-beam surveys, without advocating for specific survey patterns or interpolation techniques. 

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4. Antarctic Topographic Realizations and Geostatistical Modeling Used to Map Subglacial Lakes

   https://doi.org/10.1029/2019JF005420  

   MacKie, E. J.; Schroeder, D. M.; Caers, J.; Siegfried, M. R.; Scheidt, C. (March 2020, Journal of Geophysical Research: Earth Surface)

   Antarctic subglacial lakes can play an important role in ice sheet dynamics, biology, geology, and oceanography, but it is difficult to definitively constrain their character and locations. Subglacial lake locations are related to factors including heat flux, ice surface slope, ice thickness, and bed topography, though these relationships are not fully quantified. Bed topography is particularly important for determining where water flows and accumulates, but digital elevation models of the ice sheet bed rely on interpolation and are unrealistically smooth, biasing estimates of subglacial lake location and surface area. To address this issue, we use geostatistical methods to simulate realistically rough bed topography. We use our simulated topography to predict subglacial lake distribution across the continent using a binomial logistic regression, which uses physical parameters and known lake locations to calculate the probabilities of lake occurrences. Our results suggest that topography models interpolated without appropriate geostatistics overestimate subglacial lake surface area and that total lake surface area is lower than previously predicted. We find that radar‐detected lakes are more likely to occur in the interior of East Antarctica, while altimetry‐detected (active) lakes are expected to be found in West Antarctica and near the grounding line. We observe that radar‐detected lakes have a high correlation with heat flux and ice thickness, while active lakes are associated with higher ice velocity. 

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5. GeoLatent: A Geometric Approach to Latent Space Design for Deformable Shape Generators

   https://doi.org/10.1145/3618371  

   Yang, Haitao; Sun, Bo; Chen, Liyan; Pavel, Amy; Huang, Qixing (December 2023, ACM Transactions on Graphics)

   We study how to optimize the latent space of neural shape generators that map latent codes to 3D deformable shapes. The key focus is to look at a deformable shape generator from a differential geometry perspective. We define a Riemannian metric based on as-rigid-as-possible and as-conformal-as-possible deformation energies. Under this metric, we study two desired properties of the latent space: 1) straight-line interpolations in latent codes follow geodesic curves; 2) latent codes disentangle pose and shape variations at different scales. Strictly enforcing the geometric interpolation property, however, only applies if the metric matrix is a constant. We show how to achieve this property approximately by enforcing that geodesic interpolations are axis-aligned, i.e., interpolations along coordinate axis follow geodesic curves. In addition, we introduce a novel approach that decouples pose and shape variations via generalized eigendecomposition. We also study efficient regularization terms for learning deformable shape generators, e.g., that promote smooth interpolations. Experimental results on benchmark datasets show that our approach leads to interpretable latent codes, improves the generalizability of synthetic shapes, and enhances performance in geodesic interpolation and geodesic shooting. 

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