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The majority of the underground environments are uncharted or inadequately mapped, including human-made tunnels, underground infrastructure, and natural cave networks. The lack of GPS, constrained passages, dark or dust-filled air inhibit safe and speedy underground military operations.
To solve this problem the US military wants to develop technologies for advanced mapping and surveying in the subterranean domain. Georeferenced data, (i.e., geographic coordinates tied to a map or image) could significantly improve the speed and accuracy of warfighters in time-sensitive active combat operations and disaster-related missions in this environment.

The US Defense Advanced Research Projects Agency (DARPA) is looking for innovative technologies to collect highly accurate and reproducible ground-truth data for subterranean environments, which would potentially disrupt and positively leverage the subterranean domain without prohibitive cost and with less risk to human lives.
Warfighters and first responders could benefit from these technologies in exploring human-made tunnel systems, urban underground, and natural cave networks that are too dangerous, dark, dirty, or deep to risk human lives for deployment.
Timothy Chung, program manager in DARPA’s Tactical Technology Office (TTO) said: “Building an accurate three-dimensional picture is a key enabler to rapidly and remotely exploring and searching subterranean spaces.”
DARPA is looking for commercial products, software, and services available to enable high-fidelity, 3D mapping and surveying of underground environments. Of interest are available technologies that offer high accuracy and high resolution, with the ability to provide precise and reproducible survey points without reliance on substantial infrastructure (e.g., access to global fixes underground), according to americansecuritytoday.com.