@article {3460,
	title = {Statewide USGS 3DEP Lidar Topographic Differencing Applied to Indiana, USA},
	journal = {Remote Sensing},
	volume = {14},
	year = {2022},
	pages = {847},
	abstract = {Differencing multi-temporal topographic data (radar, lidar, or photogrammetrically derived point clouds or digital elevation models\&mdash;DEMs) measures landscape change, with broad applications for scientific research, hazard management, industry, and urban planning. The United States Geological Survey\&rsquo;s 3D Elevation Program (3DEP) is an ambitious effort to collect light detection and ranging (lidar) topography over the United States\&rsquo; lower 48 and Interferometric Synthetic Aperture Radar (IfSAR) in Alaska by 2023. The datasets collected through this program present an important opportunity to characterize topography and topographic change at regional and national scales. We present Indiana statewide topographic differencing results produced from the 2011\&ndash;2013 and 2016\&ndash;2020 lidar collections. We discuss the insights, challenges, and lessons learned from conducting large-scale differencing. Challenges include: (1) designing and implementing an automated differencing workflow over 94,000 km2 of high-resolution topography data, (2) ensuring sufficient computing resources, and (3) managing the analysis and visualization of the multiple terabytes of data. We highlight observations including infrastructure development, vegetation growth, and landscape change driven by agricultural practices, fluvial processes, and natural resource extraction. With 3DEP and the U.S. Interagency Elevation Inventory data, at least 37\% of the Contiguous 48 U.S. states are already covered by repeat, openly available, high-resolution topography datasets, making topographic differencing possible.},
	issn = {2072-4292},
	doi = {10.3390/rs14040847},
	url = {https://www.mdpi.com/2072-4292/14/4/847},
	author = {Scott, Chelsea and Beckley, Matthew and Phan, Minh and Zawacki, Emily and Crosby, Christopher and Nandigam, Viswanath and Arrowsmith, Ramon}
}
@article {3410,
	title = {Measuring change at Earth{\textquoteright}s surface: On-demand vertical and three- dimensional topographic differencing implemented in OpenTopography},
	journal = {Geosphere},
	year = {2021},
	month = {May},
	abstract = {Topographic differencing measures landscape change by comparing multitemporal high-resolution topography data sets. Here, we focused on two types of topographic differencing: (1) Vertical differencing is the subtraction of digital elevation models (DEMs) that span an event of interest. (2) Three-dimensional (3-D) differencing measures surface change by registering point clouds with a rigid deformation. We recently released topo-graphic differencing in OpenTopography where users perform on-demand vertical and 3-D differencing via an online interface. OpenTopography is a U.S. National Science Foundation{\textendash}funded facility that provides access to topographic data and processing tools. While topographic differencing has been applied in numerous research studies, the lack of standardization, particularly of 3-D differencing, requires the customization of processing for individ-ual data sets and hinders the community{\textquoteright}s ability to efficiently perform differencing on the growing archive of topography data. Our paper focuses on streamlined techniques with which to efficiently difference data sets with varying spatial resolution and sensor type (i.e., optical vs. light detection and ranging [lidar]) and over variable landscapes. To optimize on-demand differencing, we considered algorithm choice and displacement resolution. The optimal resolution is controlled by point density, landscape characteristics (e.g., leaf-on vs. leaf-off), and data set quality. We provide processing options derived from metadata that allow users to produce optimal high-quality results, while experienced users can fine tune the parameters to suit their needs. We anticipate that the differencing tool will expand access to this state-of-the-art technology, will be a valuable educational tool, and will serve as a template for differencing the growing number of multitemporal topography data sets.},
	issn = {1553-040X},
	doi = {10.1130/GES02259.1},
	url = {https://doi.org/10.1130/GES02259.1},
	author = {Scott, Chelsea and Phan, Minh and Nandigam, Viswanath and Crosby, Christopher and Arrowsmith, J. Ramon}
}
@article {3372,
	title = {OpenAltimetry-rapid analysis and visualization of Spaceborne altimeter data},
	journal = {Earth Science Informatics},
	year = {2020},
	pages = {1{\textendash}10},
	author = {Khalsa, Siri Jodha S and Borsa, Adrian and Nandigam, Viswanath and Phan, Minh and Lin, Kai and Crosby, Christopher and Fricker, Helen and Baru, Chaitan and Lopez, Luis}
}
@article {3340,
	title = {Leading Progress in Digital Terrain Analysis and Modeling},
	journal = {ISPRS International Journal of Geo-Information},
	volume = {8},
	year = {2019},
	pages = {372},
	abstract = {Digital Terrain analysis (DTA) and modeling has been a flourishing interdisciplinary field for decades, with applications in hydrology, geomorphology, soil science, engineering projects and computer sciences. Currently, DTA is characterized by a proliferation of multispectral data from new sensors and platforms, driven by regional and national governments, commercial businesses, and scientific groups, with a general trend towards data with higher spatial, spectral or temporal resolutions. Deriving meaningful and interpretable products from such a large pool of data sources sets new challenges. The articles included in this special issue (SI) focuses on terrain analysis applications that advance the fields of hydrology, geomorphology, soil science, geographic information software (GIS), and computer science. They showcase challenging examples of DTA tackling different subjects or different point of views on the same subject.},
	issn = {2220-9964},
	doi = {10.3390/ijgi8090372},
	url = {https://www.mdpi.com/2220-9964/8/9/372},
	author = {Sofia, Giulia and Eltner, Anette and Nikolopoulos, Efthymios and Crosby, Christopher}
}
@conference {3242,
	title = {Advancing Analysis of High Resolution Topography Using Distributed HPC Resources in OpenTopography},
	booktitle = {Proceedings of the Practice and Experience in Advanced Research Computing 2017 on Sustainability, Success and Impact},
	year = {2017},
	publisher = {ACM},
	organization = {ACM},
	address = {New York, NY, USA},
	keywords = {Data, HPC, LIDAR, science gateway, Software, topography},
	isbn = {978-1-4503-5272-7},
	doi = {10.1145/3093338.3093345},
	url = {http://doi.acm.org/10.1145/3093338.3093345},
	author = {Nandigam, Viswanath and Crosby, Christopher and Arrowsmith, Ramon and Phan, Minh and Lin, Kai and Gross, Benjamin}
}
@proceedings {3087,
	title = {Leveraging XSEDE HPC resources to address computational challenges with high-resolution topography data},
	year = {2014},
	address = {Atlanta, GA},
	url = {http://dl.acm.org/citation.cfm?doid=2616498.2616564},
	author = {Choonhan Youn and Viswanath Nandigam and Minh Phan and David Tarboton and Nancy Wilkins-Diehr and Chaitan Baru and Christopher J Crosby and Anand Padmanabhan and Shaowen Wang}
}
@article {3089,
	title = {Seamless Synthetic Aperture Radar Archive for Interferometry Analysis},
	journal = {ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences},
	volume = {XL-1},
	year = {2014},
	pages = {65{\textendash}72},
	doi = {10.5194/isprsarchives-XL-1-65-2014},
	url = {http://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XL-1/65/2014/},
	author = {Baker, S. and Chaitan Baru and Bryson, G. and Buechler, B. and Christopher J Crosby and Fielding, E. and Meertens, C. and Nicoll, J. and Choonhan Youn}
}
@article {3090,
	title = {CyberGIS software: a synthetic review and integration roadmap},
	journal = {International Journal of Geographical Information Science},
	volume = {27},
	year = {2013},
	pages = {2122-2145},
	doi = {10.1080/13658816.2013.776049},
	url = {http://dx.doi.org/10.1080/13658816.2013.776049},
	author = {Shaowen Wang and Luc Anselin and Budhendra Bhaduri and Christopher J Crosby and Michael F. Goodchild and Yan Liu and Timothy L. Nyerges}
}
@conference {3088,
	title = {Integration of Science Gateways: A Case Study with CyberGIS and OpenTopography},
	booktitle = {Proceedings of the Conference on Extreme Science and Engineering Discovery Environment: Gateway to Discovery},
	year = {2013},
	publisher = {ACM},
	organization = {ACM},
	address = {New York, NY, USA},
	keywords = {CyberGIS, integration, OpenTopography, science gateway},
	isbn = {978-1-4503-2170-9},
	doi = {10.1145/2484762.2484808},
	url = {http://doi.acm.org/10.1145/2484762.2484808},
	author = {Anand Padmanabhan and Choonhan Youn and Hwang, Myunghwa and Liu, Yan and Wang, Shaowen and Nancy Wilkins-Diehr and Christopher J Crosby}
}
@inbook {3091,
	title = {Online access and processing of LiDAR topography data},
	booktitle = {Geoinformatics},
	year = {2011},
	pages = {251{\textendash}265},
	publisher = {Cambridge University Press},
	organization = {Cambridge University Press},
	isbn = {9780511976308},
	url = {http://dx.doi.org/10.1017/CBO9780511976308.017},
	author = {Christopher J Crosby and Ram{\'o}n J Arrowsmith and Viswanath Nandigam and Chaitan Baru},
	editor = {G. Randy Keller and Chaitan Baru}
}
@conference {3093,
	title = {OpenTopography: A Services Oriented Architecture for Community Access to LIDAR Topography},
	booktitle = {Proceedings of the 2Nd International Conference on Computing for Geospatial Research \& Applications},
	year = {2011},
	publisher = {ACM},
	organization = {ACM},
	address = {New York, NY, USA},
	keywords = {cyberinfrastructure, LIDAR, SOA},
	isbn = {978-1-4503-0681-2},
	doi = {10.1145/1999320.1999327},
	url = {http://doi.acm.org/10.1145/1999320.1999327},
	author = {Sriram Krishnan and Christopher J Crosby and Viswanath Nandigam and Phan, Minh and Cowart, Charles and Chaitan Baru and Ram{\'o}n J Arrowsmith}
}
@inbook {3092,
	title = {Scientific workflows for the geosciences: An emerging approach to building integrated data analysis systems},
	booktitle = {Geoinformatics},
	year = {2011},
	pages = {237{\textendash}250},
	publisher = {Cambridge University Press},
	organization = {Cambridge University Press},
	isbn = {9780511976308},
	url = {http://dx.doi.org/10.1017/CBO9780511976308.016},
	author = {Ilkay Altintas and Daniel Crawl and Christopher J Crosby and Peter Cornillon},
	editor = {G. Randy Keller and Chaitan Baru}
}
@inbook {3095,
	title = {Database Design for High-Resolution LIDAR Topography Data},
	booktitle = {Scientific and Statistical Database Management},
	series = {Lecture Notes in Computer Science},
	volume = {6187},
	year = {2010},
	pages = {151-159},
	publisher = {Springer Berlin Heidelberg},
	organization = {Springer Berlin Heidelberg},
	isbn = {978-3-642-13817-1},
	doi = {10.1007/978-3-642-13818-8_12},
	url = {http://dx.doi.org/10.1007/978-3-642-13818-8_12},
	author = {Viswanath Nandigam and Chaitan Baru and Christopher J Crosby}
}
@article {3094,
	title = {Evaluation of MapReduce for Gridding LIDAR Data},
	journal = {2013 IEEE 5th International Conference on Cloud Computing Technology and Science},
	year = {2010},
	pages = {33-40},
	isbn = {978-0-7695-4302-4},
	doi = {http://doi.ieeecomputersociety.org/10.1109/CloudCom.2010.34},
	author = {Sriram Krishnan and Chaitan Baru and Christopher J Crosby}
}
@article {3096,
	title = {Illuminating Northern California{\textquoteright}s Active Faults},
	journal = {Eos, Transactions American Geophysical Union},
	volume = {90},
	year = {2009},
	pages = {55{\textendash}55},
	keywords = {active faults, Continental margins: transform, General or miscellaneous, GEON OpenTopography Portal, LIDAR, North America, Paleoseismology, Tectonics and landscape evolution},
	issn = {2324-9250},
	doi = {10.1029/2009EO070002},
	url = {http://dx.doi.org/10.1029/2009EO070002},
	author = {Prentice, Carol S. and Christopher J Crosby and Whitehill, Caroline S. and Ram{\'o}n J Arrowsmith and Furlong, Kevin P. and Phillips, David A.}
}
@mastersthesis {3098,
	title = {A Geoinformatics Approach to LiDAR Data Distribution and Processing w/ Applications to Geomorphology},
	year = {2006},
	month = {08/2006},
	school = {Arizona, Arizona State University},
	type = {MS Thesis},
	address = {Tempe},
	url = {http://users.sdsc.edu/~ccrosby/Crosby_MS_thesis.pdf},
	author = {Christopher J Crosby}
}
@inbook {3097,
	title = {A Three Tier Architecture for LiDAR Interpolation and Analysis},
	booktitle = {Computational Science {\textendash} ICCS 2006},
	series = {Lecture Notes in Computer Science},
	volume = {3993},
	year = {2006},
	pages = {920-927},
	publisher = {Springer Berlin Heidelberg},
	organization = {Springer Berlin Heidelberg},
	isbn = {978-3-540-34383-7},
	doi = {10.1007/11758532_123},
	url = {http://dx.doi.org/10.1007/11758532_123},
	author = {Jaeger-Frank, Efrat and Christopher J Crosby and Memon, Ashraf and Viswanath Nandigam and Ram{\'o}n J Arrowsmith and Conner, Jeffery and Ilkay Altintas and Chaitan Baru},
	editor = {Alexandrov, VassilN. and van Albada, GeertDick and Sloot, PeterM.A. and Dongarra, Jack}
}
