Geospatial data collections are now available in a multiplicity of domains. The accompanying data volumes, variety, and diversity of encoding formats within these collections have all continued to grow. These data offer opportunities to extract patterns, understand phenomena, and inform decision making by fitting models to the data. To ensure accuracy and effectiveness, these models need to be constructed at geospatial extents/scopes that are aligned with the nature of decision-making — administrative boundaries such as census tracts, towns, counties, states etc. This entails construction of a large number of models and orchestrating their accompanying resource requirements (CPU, RAM and I/O) within shared computing clusters. In this study, we describe our methodology to facilitate model construction at scale by substantively alleviating resource requirements while preserving accuracy. Our benchmarks demonstrate the suitability of our methodology.

Challenges in interactive visualizations over satellite data collections stem primarily from their inherent data volumes. Enabling interactive visualizations of such data results in both processing and I/O (network and disk) on the server side. These are further exacerbated by multiple, concurrent requests issued by different clients. Hotspots may also arise when multiple users are interested in a particular geographical extent. We propose a novel methodology to support interactive visualizations over voluminous satellite imagery. Our system, codenamed Glance, generates models that once installed on the client side, substantially alleviate resource requirements on the server side. Our system dynamically generates imagery during zoom-in operations. Glance also supports image refinements using partial high-resolution information when available. Glance is based broadly on a deep Generative Adversarial Network, and our model is space-efficient to facilitate memory-residency at the clients. We supplement Glance with a module to estimate rendering errors when using the model to generate imagery as opposed to a resource-intensive query-and-retrieve operation to the server. Benchmarks to profile our methodology show substantive improvements in interactivity with up to 23x reduction in time lags without utilizing GPU and 297x-6627x reduction while harnessing GPU. Further, the perceptual quality of the images from our generative model is robust with PSNR values ranging from 32.2-40.5, depending on the scenario and upscale factor.

There has been a substantial growth in remotely sensed hyperspectral satellite imagery. These data offer opportunities to understand phenomena and inform decision making. The nature of these collections introduces challenges stemming from their volumes, variety, and spatiotemporal resolutions. The crux of this study is to facilitate effective training of deep learning models over satellite data collections. We describe our novel embeddings (multidimensional latent space representations) based approach to effectively support model training, refinement, and inferences. We rigorously explore several aspects relating to embeddings, including their dimensionality, single vs multiple bands, and preservation of inter-band metrics. We also incorporate support for transfer learning over spatiotemporal scopes to address issues relating to cold start and alleviate resource pressure. Our methodology addresses disk, network, CPU/GPU, and accuracy implications of several aspects relating to model construction. Our empirical benchmarks assess the suitability of our methodology using the MODIS and Sentinel-2 satellite data. We demonstrate that our methodology reduces storage requirements by more than 10,000x and reduces model construction times by 75%.

There has been an exponential growth in data volumes in several domains. Often these voluminous datasets encompass a large number of features. Fitting models to such high-dimensional, voluminous data allows us to understand phenomena and inform decision-making. The analytics process is naturally iterative as scientists explore the set of features, data fitting algorithms, portions of the dataspace, and the particular algorithm's hyperparameters to guide their model-building process. It often takes several model-fitting attempts before one arrives at a satisfactory solution that may then be subjected to further refinements. Each of these model-building attempts is itself time-consuming and dominated by I/O and data movement costs. In this study, we present our methodology for significantly alleviating I/O-induced inefficiencies during model training. Rather than work with the raw data, we generate and work with sketches of the data. Our framework, Fennel, is independent of the libraries or analytical engines preferred by users. Our empirical benchmarks have been performed with datasets from diverse domains (weather, epidemiology, and music) and we profile several aspects of our methodology.