TriMedium: A Cross-Medium Simulator for Embodied Networking Across Air-Ground-Sea

Embodied intelligent applications have expanded from air and ground into maritime environments, where missions such as coastal reporting require coordination among underwater sensing, surface gateways, and aerial relays. Yet field trials remain costly, and existing simulation tools make it difficult to study how cross-medium communication affects cooperation among these platforms. We present TriMedium, an integrated Air-Ground-Sea simulator for cross-medium embodied networking. TriMedium has three design elements. First, it provides a shared three-dimensional world where aerial, terrestrial, and underwater entities coexist, so underwater agent motion and visual observations stay geometrically consistent with air and ground nodes. Second, it uses a common simulation clock that preserves observation timestamps while scheduling delayed communication and computation, clarifying when the shore receiver obtains each observation. Third, modular quantization and compression interfaces accommodate heterogeneous telemetry and image pipelines, while integrity checks separate intentional lossy distortion from incomplete or corrupted delivery. Three case studies validate TriMedium. Multimodal data delivery tests telemetry and image pipelines, scene construction examines cross-domain spatial consistency, and positioning assesses geometric accuracy under delayed communication. Together, they show TriMedium enables embodied networking by quantifying cross-medium delivery dynamics and fidelity across heterogeneous payloads.