In This Article Expand or collapse the "in this article" section Unoccupied Aircraft Systems

  • Introduction
  • General Overviews
  • Textbooks
  • Journals
  • Teaching and Learning
  • Regulations and Operation
  • Critical Geographies of UAS

Geography Unoccupied Aircraft Systems
Adam Mathews
  • LAST MODIFIED: 27 October 2022
  • DOI: 10.1093/obo/9780199874002-0245


An unoccupied aircraft system or UAS is comprised of an aircraft (typically, fixed- or rotary-wing) and the equipment needed to remotely operate the aircraft including a remote controller, additional ground control (e.g., computing station), and communication between components. UAS are otherwise known as drones, unoccupied/uncrewed/unmanned aerial vehicles (UAVs), and remotely piloted aircraft systems (RPAS) among others. In most cases, UAS refer to non-military small UAS (sUAS) that adhere to civil aviation size/weight requirements such as weighing less than 55 pounds (about 25 kilograms) in the United States as regulated by the Federal Aviation Administration (FAA) or the equivalent civil aviation authority in other countries. To geographers and geographic information scientists (GIScientists), UAS enable the collection of very high-spatial and -temporal resolution aerial data for a relatively low-cost compared to more traditional means (e.g., field-based surveys, weather balloons, occupied/piloted aircraft, satellites). The low-cost and relative ease of operation of UAS supports adoption of the technology in geographic research and teaching efforts. GIScientists including remote sensing experts have been quick to incorporate UAS into their work to examine geographic problems at unprecedented spatial and temporal scales. In this way, UAS as a topic cannot be separated from remote sensing because the technology is primarily used to remotely sense Earth’s surface using optical sensors (e.g., images, video), lidar, and radar. Digital photogrammetric methods tie together overlapping aerial images to generate three-dimensional (3D) point clouds and orthophotos. Specifically, images are processed using a suite of computer vision algorithms referred to together as Structure from Motion-Multiview Stereo (SfM-MVS, SfM for short) photogrammetry. Geographers focusing on areas outside of geospatial techniques, though, also utilize UAS. These include physical geographers interested in modeling landforms and fluvial processes as well as human geographers interested in community-based work, social research, and/or ethical issues with UAS usage and data collection. It is important to note though that the topic of UAS is multi- and interdisciplinary. Design and development of UAS technology requires contributions from engineering and computer science among other fields, and UAS operation involves aspects of airspace regulation, aviation law, and policy. Here we focus on conceptual and applied aspects of UAS from the perspective of geography, but references from cognate fields are included when needed.

General Overviews

Conceptual works and meta-analyses (review papers) are incredibly important to those implementing unoccupied aircraft system (UAS) technology in their research. They can provide a broad background on the topic while also guiding readers to subfields of interest with their organization of content and extensive reference lists. Further, these works can help to conceptually frame the topic within a discipline or research area. Colomina and Molina 2014; Hardin and Hardin 2010; Pajares 2015; Tmušić, et al. 2020; and Watts, et al. 2012 contribute overarching reviews of UAS technology in the context of geographic and environmental research. Cummings, et al. 2017 and Singh and Frazier 2018 provide additional detail through meta-analysis and quantification of trends within published UAS research. Lippitt and Zhang 2018 and Simic Milas, et al. 2018 offer perspective on how UAS fits within the field of remote sensing while Hardin, et al. 2019 outlines challenges to UAS integration into geographic research.

  • Colomina, I., and P. Molina. “Unmanned Aerial Systems for Photogrammetry and Remote Sensing: A Review.” ISPRS Journal of Photogrammetry and Remote Sensing 92 (2014): 79–97.

    DOI: 10.1016/j.isprsjprs.2014.02.013

    Comprehensive review article on UAS in photogrammetry and remote sensing covering history of the topic, aircraft types and operation, regulations, sensor payloads, data processing, and remote sensing applications. Provides an all-inclusive overview of UAS for remote sensing that can be useful to those new to the topic as well as those with some background.

  • Cummings, A. R., A. McKee, K. Kulkarni, and N. Markandey. “The Rise of UAVs.” Photogrammetric Engineering & Remote Sensing 83.4 (2017): 317–325.

    DOI: 10.14358/PERS.83.4.317

    This article emphasizes the change occurring within photogrammetry and remote sensing due to the low cost and high availability of UAS technology. The article quantifies trends within peer-reviewed literature including types of aircraft and software used, number of civil aviation authorizations over time, and a summary of ethical and safety concerns.

  • Hardin, P. J., and T. J. Hardin. “Small-Scale Remotely Piloted Vehicles in Environmental Research.” Geography Compass 4.9 (2010): 1297–1311.

    DOI: 10.1111/j.1749-8198.2010.00381.x

    This article reviews literature on the common UAS application areas in forestry and land/wildlife management, agricultural monitoring, and other environmental applications. Further, background is provided about UAS technology and adoption as well as benefits and limitations presented by it.

  • Hardin, P. J., V. Lulla, R. R. Jensen, and J. R. Jensen. “Small Unmanned Aerial Systems (sUAS) for Environmental Remote Sensing: Challenges and Opportunities Revisited.” GIScience & Remote Sensing 56.2 (2019): 309–322.

    DOI: 10.1080/15481603.2018.1510088

    This article highlights challenges presented by UAS within GIScience and remote sensing research such as aircraft operation (e.g., remote piloting skill, legal/regulatory limitations), technological limitations (e.g., battery/flight times, quality and availability of sensors, payload weight restrictions), and data processing (i.e., data handling and analysis). This article updates an earlier edition by Hardin and Jensen (2011).

  • Lippitt, C. D., and S. Zhang. “The Impact of Small Unmanned Airborne Platforms on Passive Optical Remote Sensing: A Conceptual Perspective.” International Journal of Remote Sensing 39.15–16 (2018): 4852–4868.

    DOI: 10.1080/01431161.2018.1490504

    This work conceptualizes the influence of UAS within optical remote sensing using the Remote Sensing Model and Remote Sensing Communication Model, and by emphasizing very high spatial resolution data that necessitate H-resolution approaches such as object-based image analysis. Importantly, the article stresses the challenges presented by UAS within remote sensing research and outlines research priorities in the areas of algorithms, computing architecture, autonomous operation, and sensor advancement.

  • Pajares, G. “Overview and Current Status of Remote Sensing Applications Based on Unmanned Aerial Vehicles (UAVs).” Photogrammetric Engineering & Remote Sensing 81.4 (2015): 281–329.

    DOI: 10.14358/PERS.81.4.281

    Review article on UAS remote sensing for wide-ranging applications (e.g., agriculture, atmosphere, archaeology, conservation, urban environments). Importantly, this article emphasizes sensing beyond optical images and video (e.g., visible, multi-/hyperspectral, thermal) including radar, lidar, sonar, chemical and magnetic sensing, and atmospheric measurement.

  • Simic Milas, A., A. P. Cracknell, and T. A. Warner. “Drones—The Third Generation Source of Remote Sensing Data.” International Journal of Remote Sensing 39.21 (2018): 7125–7137.

    DOI: 10.1080/01431161.2018.1523832

    Editorial article that presents UAS technology as the third generation of remote sensing platforms following piloted/occupied aircraft and Earth-orbiting satellites. Provides historical context for UAS as remote sensing platforms and stresses the importance of safe UAS operation.

  • Singh, K. K., and A. E. Frazier. “A Meta-analysis and Review of Unmanned Aircraft System (UAS) Imagery for Terrestrial Applications.” International Journal of Remote Sensing 39.15–16 (2018): 5078–5098.

    DOI: 10.1080/01431161.2017.1420941

    Review paper that summarizes research trends in both theoretical and applied UAS remote sensing. The study highlights the diversity of UAS applications as well as the lack of standardized UAS data collection procedures.

  • Tmušić, G., S. Manfreda, H. Aasen, et al. “Current Practices in UAS-Based Environmental Monitoring.” Remote Sensing 12.6 (2020): 1001.

    DOI: 10.3390/rs12061001

    This review article summarizes the UAS remote sensing research process including study design (e.g., platform choice, regulatory compliance), pre-flight and flight fieldwork (e.g., ground control points, other field data collection, UAS mission planning), aerial data processing (e.g., geometric and radiometric processing, SfM-MVS), and quality assurance (e.g., check point assessment). Provides a comprehensive guide for those learning to conduct UAS remote sensing research.

  • Watts, A. C., V. G. Ambrosia, and E. A. Hinkley. “Unmanned Aircraft Systems in Remote Sensing and Scientific Research: Classification and Considerations of Use.” Remote Sensing 4 (2012): 1371–1692.

    DOI: 10.3390/rs4061671

    Broad review of UAS technology for remote sensing research emphasizing classification of aircraft by flight capability (including aircraft larger than sUAS). Historical perspective on UAS is provided as well as information on airspace regulation and a variety of environmental, primarily NASA-led, applications.

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