Geographic Information Systems (GIS)
What is GIS?
A Geographic Information System (GIS) is a computer system that analyzes and displays geographically referenced information from a variety of data sources to map and examine changes on Earth. GIS allows for the integration and collective analysis of geospatial data from multiple sources, including satellite imagery, GPS recordings, and textual attributes associated with a particular space.
GIS components include:
- Visualizations through interactive maps
- Data based on the location of features or variables represented
- Spatial analytic functions that focus on identifying trends and patterns across space and time
- Applications that enable tools and services in user-friendly interfaces
Remote sensing data and imagery from Earth observations can be visualized within a GIS to provide more context about any area under study. GIS is used in nearly all fields that need to understand the spatial patterns and relationships between different datasets, such as land-use planning, emergency response, and resource management. The need is growing for NASA Earth science data to be in GIS-ready formats for easy integration and analysis in the primary tools employed by user communities.
Overview of Multidimensional Data in GIS
Geospatial data are collected in a variety of ways. They can be remotely sensed from instruments aboard airplanes and satellites, created from imagery, or acquired in the field. GIS data contain spatial coordinates to represent where features are located. This is typically done using X (longitude) and Y (latitude) coordinates. Multidimensional data represent data that are acquired at different dimensions such as depths, heights, and times (z). GIS data contain spatial coordinates to represent where features are located. These data associated metadata are stored in scientific data formats used by the Earth science community.
Multidimensional data formats share common structures for storing multiple variables, with each variable being a multidimensional array in a raster format. These most common specialized formats include, Network Common Data Form (NetCDG), Hierarchical Data Format (HDF), and General Regularly-distributed Information in Binary (GRIB). Some of the more common cloud-ready formats include Cloud Optimized GeoTIFF (COG), Meta Raster Format (MRF), and Cloud Raster Format (CRF).
In tools such as QGIS and ArcGIS, support for raster data is provided using a mosaic dataset. A mosaic dataset is a data model that acts as a shell to input a collection of multiple raster files that include different file formats and is viewed as a single image. A multidimensional mosaic dataset stores information about the dimensions and variables as fields in the mosaic dataset footprint table. The underlying raster data do not have to be connecting or overlapping, but can be isolated or intermittent datasets. In some GIS software platforms, a single mosaic dataset can then be used to query, process, analyze, and serve data. For more information about mosaic datasets, see the Esri article What are mosaic datasets?
In recent years, GIS software has increased support for scientific data formats in their platforms. In addition to correctly ingesting and reading these files, primary software platforms have developed new tools to aid in common workflows along with the management, analysis, and distribution of multidimensional data.
For tutorials and guidelines on using multidimensional NASA data in a GIS, visit the GIS Data Pathfinder.
GIS tools rely on information stored in data files to determine the correct method of visualization. Often, this relies on Coordinate Systems (the values used to define a position within a spatial reference to represent location when capturing the data) as well as Projections (how the values are located and displayed on a map).
NASA scientific data work well in GIS tools if they are created using standards such as the Hierarchical Data Format - Earth Observing System (HDF-EOS) and conventions such as Climate Forecast (CF). These help ensure the data are formatted in a way for tools to read and write. However, not all complex scientific data can be read easily or understood by libraries such as the Geospatial Data Abstraction Library (GDAL), which tells software what information to parse from data files and how to display them properly.
Using GIS tools, users can perform a multitude of spatial analyses to determine patterns or trends across space. GIS analysis is used to detect change, extract features, identify relationships, interpolate data, calculate statistics, determine viewsheds, and find optimal routes. GIS tools also help researchers employ machine learning and deep learning models to enhance the use of Big Data collections and make more accurate predictions.
To see use cases for how NASA data are employed in a GIS to analyze and assess phenomena, visit the GIS Data Pathfinder.
GIS tools enable the user to do more than creating maps. Although cartography is the foundation for GIS technology, modern technology allows GIS practitioners to create and publish web mapping services, develop powerful user-intuitive applications, create interactive dashboards, and tell effective stories with data alongside narration and media. These methods allow content to be distributed to broad audiences in ways that are easy to digest, explore, and utilize as well as integrate with content of their own. Expanding beyond traditional maps allows NASA to increase awareness and exposure within new communities and aids in the understanding and use of science data.
NASA’s GIS Services and Products
The vision of NASA's Earth Science Data Systems (ESDS) Program is to identify and deliver high value Earth science data in formats compliant and compatible with GIS standards; to ensure data are interactive, interoperable, accessible, and GIS-enabled through primary GIS platforms; and to provide the maximum impact to research, education, and public user communities requiring data visualization and spatial analysis.
The ESDS Geographic Information Systems Team (EGIST), located at NASA’s Langley Research Center in Hampton, VA, was created to provide sustained program-wide support to enable the appropriate use and adoption of GIS technology in support of Earth science research and applied science for EOSDIS data. In addition, numerous geospatial web services and tools are available through NASA DAACs to access GIS-ready data.
Data and Services
NASA data are openly available to researchers and the public. Earthdata Search provides the means for discovering, filtering, and accessing these data across all of NASA’s Earth science data holdings. This includes more than 33,000 Earth observation data collections.
|NOTE: While NASA data are available in a number of scientific formats, not all data are GIS-ready and not all files can be ingested easily into GIS systems without error or complications. Visit the Earthdata Forum to interact with NASA subject matter experts who can answer any questions that may arise.|
NASA Worldview provides the ability to interactively browse and download full-resolution, global satellite imagery from over 1,000 data products available through NASA's Global Imagery Browse Services (GIBS). GIBS provides access to global, full-resolution imagery from satellite imagery products via a variety of standards-based web services, such as Web Map Tile Services (WMTS), Tiled Web Map Service (TWMS), Web Map Services (WMS), and Keyhole Markup Language (KML). Most imagery is updated daily and available within a few hours after satellite observation; some product records span almost 30 years.
NASA also utilizes Esri’s ArcGIS Online—a collaborative web GIS that allows users to use, create, and share data, layers, maps, applications, and analytic products. NASA’s publicly available content includes web services, dashboards, notebooks, and StoryMaps.
Selected authoritative content is also registered to Esri’s Living Atlas of the World, which features imagery layers provided by EOSDIS.
Ready to get started?
The GIS Data Pathfinder provides a guided walkthrough of NASA data in GIS tools; links to the tools from which data can be visualized, subset, and downloaded in different file formats; and a brief tutorial on using GIS tools to access NASA geospatial web services.
Already on your way?
If you already are familiar with using NASA Earth observation data, you still may need some help navigating the complexities of working with these data. NASA's EOSDIS has Tutorials/How-To Guides and Data Recipes to help you navigate the complexities of data processing and transformation to GIS use. If you are interested in receiving expert advice, check out the Earthdata Forum, where subject matter experts from several NASA DAACs are available to discuss general questions, research needs, and data applications. Within the “Search by Tags” box, under “Services/Usage” select “GIS Tools” from the dropdown.
The EGIST team would love to hear from you! Understanding your data needs to include what format, distribution method, and application or tool used to work with the data helps us improve our services.
Published April 14, 2022
Page Last Updated: Apr 15, 2022 at 9:28 AM EDT