Geographic Information Systems (GIS) are fueled by geospatial data. This comprehensive article reviews the evolution of procedures and technologies used to create the data that fostered the explosion of GIS applications. It discusses the need to geographically reference different types of information to establish an integrated computing environment that can address a wide range of questions. This includes the conversion of existing maps and aerial photos into georeferenced digital data. It covers the advancements in manual digitizing procedures and direct digital data capture. This includes the evolution of software tools used to build accurate data bases. It also discusses the role of satellite based multispectral scanners for Earth observation and how LiDAR has changed the way that we measure and represent the terrain and structures. Other sections deal with building GIS data directly from street addresses and the construction of parcels to support land record systems. It highlights the way Global Positioning Systems (GPS) technology coupled with wireless networks and cloud-based applications have spatially empowered millions of users. This combination of technology has dramatically affected the way individuals search and navigate in their daily lives while enabling citizen scientists to be active participants in the capture of spatial data. For further information on changes to data capture, see Part 2: Implications and Case Studies.
The capture of massive quantities of spatial data, able to be distributed and shared in real time, provide for an ever-increasing range of environmental and societal applications. Data capture includes the principles, methods, technologies, applications, and institutional/programmatic aspects of spatial data acquisition. Sources of data include global navigation satellite systems, satellite and aerial sensing, field surveys, land records, socioeconomic data (e.g., census), volunteered geographic information, wireless sensor networks, and unmanned aerial systems.
Topics in this Knowledge Area are listed thematically below. Existing topics are in regular font and linked directly to their original entries (published in 2006; these contain only Learning Objectives). Entries that have been updated and expanded are in bold. Forthcoming, future topics are italicized.
|History & Trends||Processing Remotely-Sensed Data|
|Changes in Data Capture Methods Over Time||Image Interpretation: Aerial Photography & Satellites|
|Georeferencing and Georectification||Feature Extraction in Satellite Imagery|
|Digital Data Sources & Capture Methods||Ground Verification and Accuracy Assessment|
|Historical (Paper) Maps||Spectral Properties of Terrestrial Surfaces|
|Global Navigation Satellite Systems||Structure from Motion Photogrammetry|
|Mobile Applications||GIS and Surveying|
|Aerial Photography: History & Georeferencing||Professional Land Surveying|
|Ground or Street-Level Imagery||Land records|
|Social Media Platforms||Ocean Surveying|
|Volunteered Geographic Information (VGI)||Field Data Collection|
|Remote Sensing Platforms & Sensors||Sampling: Size Selection, Sample Types, Intervals|
|Remote Sensing Platforms overview||Field Data Capture Technologies|
|Nature of multispectral image data||U.S. Census Data|
|Unmanned Aerial Systems (UAS)||Data Coordinating Organizations|
|Landsat||Multi-Organizational GIS Coordination|
|Light Detection and Ranging (LiDAR)||Federal Agencies & National Organizations and Programs|
|Indoor LiDAR Scanning||International Organizations & Programs|
|Radar, Sonar, and Echolocation|
|Airborne LiDAR Bathymetry|