Unfathomably, only 24% of the ocean floor has been explored and charted by humans. It not only serves as a habitat for countless marine life, but it also plays a vital role in regulating the Earth’s climate by absorbing carbon dioxide and releasing oxygen. The more we know about the ocean, the more effectively we can ensure its health for generations to come.
THE NEED FOR SUBSEA IMAGING
Subsea imaging is crucial in various fields. For industrial engineers, underwater imaging allows for detailed inspection and maintenance of offshore infrastructure, such as pipelines and cables, helping to identify and prevent catastrophic failures.
Archaeologists use high-resolution imagery to study submerged historical sites and artifacts, while marine conservationists depend on it for regular monitoring of marine ecosystems. Defense operators leverage underwater imaging for reconnaissance and surveillance purposes, making it an essential tool for military intelligence.
As the demand for underwater exploration grows, it is increasingly critical to develop versatile subsea imaging solutions that can adapt to evolving needs and ongoing challenges.
THE CHALLENGES
Taking high quality underwater imagery contrasts starkly with land surveying because of the unique challenges presented when under the sea. One of the primary differences is visibility. Underwater environments are often murky and turbid, with particles suspended in the water scattering and absorbing light rapidly. This can lead to significant lens distortion and image blurring. To further complicate matters, darkness at greater depths compounds the problem. This makes capturing clear, high-resolution imagery particularly challenging, necessitating advanced technology and techniques to mitigate these issues.
Another difference is due to the unstable and dynamic conditions of underwater environments. Strong currents, waves, and other factors not only make it challenging to capture high quality imagery, but they can also pose safety risks to divers and equipment.
The biggest hurdle for underwater exploration, however, is accessibility in terms of expense.
Traditional methods, such as divers, ROVs, and conventional AUVs require specialized equipment and expert personnel, leading to significant operational costs, which deter most organizations from making subsea dives on a regular or meaningful basis.
OVERCOMING CHALLENGES
Hydrus, a micro-AUV by Advanced Navigation offers a groundbreaking solution to the challenges of underwater exploration, providing an easier and more cost-effective way to explore the ocean and capture unprecedented detail.
The micro-AUV features the most advanced navigation and communication systems of any underwater vehicle of its size, including:
• Doppler Velocity Log: designed for relative motion tracking and obstacle avoidance underwater.
• Ultra-short Baseline Acoustic Positioning: designed to provide absolute underwater position.
• Inertial Navigation System: AI aided data fusion from all navigation inputs.
• Acoustics: tetherless commands can be sent to the vehicle while underwater.
• Imaging System: computer-vision aiding on the camera feed for object detection and classification.
Another innovation is the thruster design. Equipped with hubless thrusters, the in-house design allows seaweed and particles to move directly through, without entanglement. Several thrusters are located at various orientations, giving the vehicle six degrees of freedom of movement, and the ability to rotate and translate direction, even in high currents or rivers.
Additionally, Hydrus is equipped with AI-driven obstacle avoidance systems, allowing it to navigate complex terrains autonomously and avoid collisions. Its compact design allows for easy transportation and hand-deployment from a small boat, eliminating the need for larger vessels and expert teams. This simplicity reduces operational costs, minimizes downtime between missions and maximizes time for data capture.
By combining these advanced features, Hydrus not only overcomes the traditional limitations of underwater exploration but also sets a new standard for efficiency, accuracy, and affordability in subsea data imaging.
At the core of Hydrus’ imaging capabilities is its 4K camera and advanced sensors capable of submillimeter resolution. This precision is crucial for capturing fine details and measurements, enabling Hydrus to detect subtle changes and anomalies which would otherwise be missed. For example, in coral reef monitoring, this precision allows the growth of coral to be tracked over time. Similarly, it proves incredibly powerful for the inspection of underwater assets, enabling users to note and measure the size of defects naked to the human eye.
Impressively, Hydrus’ camera can be used to capture video and highresolution imagery simultaneously, preserving color information and other visual details despite underwater visual degradation. Intelligent camera controls featuring auto-adjusting ISO, lights, and white balance further enhance image quality.
BATHYMETRY AND PHOTOGRAMMETRY
Hydrus excels in capturing data with such precision that it enables advanced bathymetry and structure-from-motion (SfM) photogrammetry.
Traditional bathymetry involves using acoustic sensors to map underwater topography, offering low-resolution scans. SfM photogrammetry, on the other hand, reconstructs 3D structures from 2D image mosaics of multiple overlapping photos taken from different positions.
As light does not travel far underwater, capturing large areas, for example shipwrecks, can be challenging. Hydrus, however, can complete multiple survey missions of its target and piece diverse images to produce a complete picture. The results can then be combined with bathymetry data to obtain a map of the area with submillimeter resolution.
GEOREFERENCED DATA
Data captured by Hydrus also includes georeferencing. This georeferenced data can then be used with Hydrus’ inbuilt mission planning software to conduct repeat missions and long-term monitoring. By tagging each image and video frame with GNSS coordinates, Hydrus enables operators to return to specific locations and create underwater digital twins for data comparison.
When combined with Hydrus’ onboard object identification and sophisticated third-party software, Hydrus becomes a powerful tool for underwater investigations like evidence collections and search and recovery missions.
UNDERSTANDING THE OCEAN
Hydrus represents an important breakthrough in underwater imaging, overcoming many of the limitations of traditional methods. Its incorporation of state-of-the- art sensors and cameras enable it to capture data in unprecedented detail, making it a powerful tool for various applications in environmental monitoring, infrastructure inspections, marine engineering, underwater archaeology, and surveillance applications.
With its robust capabilities, Hydrus not only promises to change the way we explore underwater frontiers but also ensures high quality data acquisition. The ocean intelligence gathered will help us make more informed decisions regarding marine conservation, resource management and climate change, while adding to our collective understanding of the sea.
This story was originally featured in ON&T’s June 2024 issue. Click here to read more.
