Urban airspace is an important space where many value-creating aerial activities such as drone delivery may take place. However, not all vacant parts of urban airspace are available, since some areas may be blocked from use either temporally or permanently, in order to minimize risks to people, infrastructure, and other air users.

This research aims to find available airspace where aerial vehicles can navigate within an acceptable level of risk, utilizing high-resolution building and terrain data. Specifically, the changes in the amount of available airspace was analyzed with respect to geofence parameters in the case study area.

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Related publication

• Cho, J., & Yoon, Y. (2018). How to assess the capacity of urban airspace: A topological approach using keep-in and keep-out geofence. Transportation Research Part C: Emerging Technologies, 92, 137-149. [pdf]

• Cho, J., & Yoon, Y. (2018). Assessing the airspace availability for sUAV operations in urban environments: A topological approach using keep-in and keep-out geofence", International Conference on Research in Air Transportation 2018 Doctoral Symposium (ICRAT 2018). [pdf]

The airspace to be used by UAM aircraft is already occupied by various airspace constructs, such as arrival and departure procedures, special use airspace, and temporary flight restrictions. UAM operators should be aware of which airspace is accessible at each altitude, in order to derive safe and efficient route options.

This study aimed to find available airspace that UAM aircraft can access in four ATC integration scenarios. This study highlights that not only the amount but also the shape of available airspace depends on the types of airspace constructs to be considered, the altitude to fly at, and the amount of required separation.

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Related publication

• Vascik, P. D., Cho, J., Bulusu, V., & Polishchuk, V. (2019) A Geometric Approach Towards Airspace Assessment for Emerging Operations, ATM Seminar 2019. [pdf]

• Vascik, P. D., Cho, J., Bulusu, V., & Polishchuk, V. (2020). Geometric Approach Towards Airspace Assessment for Emerging Operations. Journal of Air Transportation, 1-10. [pdf]

In an obstacle-rich environment like UTM or UAM airspace, there needs a fast and robust method that can generate route candidates for aerial vehicles moving from one location to another.

This research proposes the use of a two-layered graph structure for fast and robust single-agent pathfinding in a large-scale 3D environment. The first-layer graph encodes the vertical connectivity of airspace based on the topological concept of Reeb graph, whereas the second-layer graph encodes the lateral connectivity of airspace using the medial axis transformation.

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Related publication

• Cho, J. (2020). Urban airspace availability assessment framework and its applications using geometric and topological algorithms (doctoral dissertation, chapter 3&4). Korea Advanced Institute of Science and Technology. [pdf]

• Cho, J., & Yoon, Y. (2019). Extraction and Interpretation of Geometrical and Topological Properties of Urban Airspace for UAS Operations, ATM Seminar 2019. [pdf]

Urban airspace is a unique environment where highly obstructed (complex topology) and sparsely structured (simple topology) regions coexist. The presence of static obstacles and the required separation from those obstacles creates particular spatial structures - narrow passages, islands, and funnels - throughout the airspace.

This study proposes a computational geometric approach to model urban airspace as a compact and informative graph structure that summarizes spatial connectivity in the horizontal and vertical dimension. A compact abstraction of airspace into a graph structure provides a basis for density-aware flight planning in urban airspace.

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Related publication
Cho, J., & Yoon, Y. (2021). Extracting the topology of urban airspace through graph abstraction. Transportation Research Part C: Emerging Technologies, 127, 103116.

Cho, J., & Yoon, Y. (2020). Segmentation of Low-altitude Airspace in Highly Constrained Environments, International Conference on Research in Air Transportation (ICRAT 2020). [pdf]