ViDAR, developed by Sentient Vision Systems in Melbourne Australia, provides autonomous, real-time, wide-area search capability, optically, from unmanned aerial vehicles (UAVs) or manned aircraft. ViDAR, which stands for Visual Detection and Ranging, essentially acts as an optical radar, using high-megapixel video or infrared cameras to search the ocean over significantly greater operational coverage areas than can be achieved with current optical sensor approaches.

Searching the ocean with optical sensors is like looking through a soda straw. The field of view (FoV), even from full HD sensors, is very limited and only useful for maintaining surveillance over objects already found using other technologies such as radar. Radar, however, is expensive and can have limitations for detecting a range of targets which are becoming of increasing importance to naval commanders, such as small rubber boats or fast attack craft. ViDAR's optical search is also entirely passive, making it well suited to covert operations such as drug interdiction. And as the disappearance of flight MH370 illustrated, searching large areas of ocean for small objects, such as debris, life rafts, or people in the water, is hugely resource intensive, slow, fatiguing for operators, and can impact the ability to save lives.

ViDAR GUI showing detection snapshots, mapped locations, and video from cued spotter camera. (Credit: Sentient)
ViDAR 5 step configuration for ScanEagle. (Credit: Sentient)
ViDAR 3 camera configuration for AMSA Challenger 604 search and rescue jet. (Credit: Sentient)

ViDAR consists of one or more commercial, off-the-shelf, high-megapixel video cameras that continuously scan the ocean 180 degrees in front of the aircraft. The video from these cameras is processed autonomously on-board the aircraft in real-time. ViDAR's algorithms analyze the pixels within each frame to detect objects on the ocean surface, discriminating them from whitecaps or environmental effects such as sun glare, haze, or mist. Over a series of frames, ViDAR learns the characteristics of these effects and factors them out from object detections.

Rather than attempt to send the full video stream to the operator, for each detection ViDAR clips out a small snapshot image. The still image and its coordinates, which are determined from the aircraft's inertial navigation system, are sent back to the operator, who may be in a ground control station for a UAV or at a mission console onboard the aircraft.

The operator simply reviews the images and mapped locations on the screen and selects those of interest for interrogation. This process automatically cues the aircraft's spotter sensor to zoom in and provide investigation of the object in detail. Whilst this is happening, ViDAR continues to scan the ocean, autonomously sending further detections to the operator.

Royal Australian Navy team on Christmas Island with ViDAR-equipped ScanEagle. (Credit: RAN)

ViDAR can be configured on a wide range of air platforms and optimized for specific mission profiles. With the Insitu ScanEagle small/tactical UAV, size, weight, and power (SWAP) are key constraints. ViDAR is added to the ScanEagle fuselage as a small, modular slice containing a 9MP camera and a low-power processor board enabling onboard autonomous processing. ViDAR is configured to rotate the camera around a 180-degree arc in a series of steps. Each step is held typically for 10s as the camera is moved around 5 positions. Gaps between the step FoVs are filled in by subsequent steps as the aircraft moves forward.

The FoV can be optimized for the types of objects being targeted, with a 20 degree FoV ensuring that a fast boat at 40 knots would be covered across the full 180 degrees in front of the aircraft. As only the object snapshots and locations are sent to the operator in the ground station, there is minimal additional data link load from ViDAR. On the ScanEagle, ViDAR provides over 80 times the coverage that could be achieved on an equivalent mission with an existing EO sensor and transforms it to an asset that can be used for finding objects rather than just watching those already found.

On larger platforms, such as manned aircraft or helicopters, ViDAR can be configured with 3 or 5 fixed cameras. Cobham SAR Services, for example, are deploying a 3-camera ViDAR system into the Challenger 604 jets, which they operate for the Australian Maritime Safety Authority's (AMSA) search and rescue service. Operating as a complementary system to their other aircraft sensors, the system is optimized to the speed, altitude, and type of objects being searched for. The video from each camera is processed continuously by ViDAR, providing realtime alerts to the mission management system operator who can then cue the primary aircraft video sensor.

Through trials and operational use with forces and service operators worldwide, ViDAR has demonstrated its ability to find small objects at great distances and in a wide range of sea state and weather conditions. The Royal Australian Navy (RAN) has been deploying ViDAR on a ScanEagle for surface search from Christmas Island and have noted the far greater coverage it enables over what could previously be achieved.

At the Royal Navy Unmanned Warrior exercise in October 2016, ViDAR performed over 55 hours of operations, effectively providing persistent wide area surveillance, detection of fast attack craft threats, and tracking of known and unknown vessels through choke points. ViDAR autonomously detected and tracked targets, such as rubber boats and jet skis, out to 13nm, naval vessels beyond 10nm, and a freighter beyond 30nm. The detections were cued to investigate and identify the targets which were then passed to the operation control team to provide increased situational awareness to the commanders of the naval fleet.

In other trials, including with the US Coast Guard, ViDAR has consistently demonstrated its autonomous detection of boats, life rafts, and even people in the water at far greater distances than could be achieved by a sensor without ViDAR or a visual search.

Through the innovative use of low-cost commercial cameras combined with low-power embedded video processing, ViDAR provides a game-changing optical radar capability for wide-area maritime search. Increasing search coverage in excess of 80 times over existing video sensors, ViDAR allows effective primary search with smaller UAVs and aircraft without radar, dramatically improving the cost effectiveness of maritime operations such as search and rescue, maritime patrol, anti-piracy, anti-narcotics, and border protection.

This article was written by Stewart Day, General Manager, Sentient Vision Systems (Melbourne, Australia). For more information, contact Mr. Day at This email address is being protected from spambots. You need JavaScript enabled to view it. or visit Here .

Photonics & Imaging Technology Magazine

This article first appeared in the March, 2017 issue of Photonics & Imaging Technology Magazine.

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