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Underwater Time Of Flight Image Acquisition system

Periodic Reporting for period 1 - UTOFIA (Underwater Time Of Flight Image Acquisition system)

Reporting period: 2015-02-01 to 2016-07-31

UTOFIA will offer a compact and cost-effective underwater imaging system for turbid environments. Using range-gated imaging, the system will extend the imaging range by factor 2 to 3 over conventional video systems, while at the same time providing video-rate 3D information. This will fill the current gap between short-range, high-resolution conventional video and long-range low-resolution sonar systems.

UTOFIA offers a new modus operandi for the main targeted domains of application: marine life monitoring, harbour and ocean litter detection, fisheries and aquaculture stock assessment, and seabed mapping.

UTOFIA's major leap in performance and cost-efficiency is made possible through an innovative combination of state-of-the-art solid-state technologies. This will take range-gated imaging from a curiosity for specialist use, to a camera suitable for a broad range of professional, commercial, and industrial applications.

The primary aim of UTOFIA is to:

Enable the cost-efficient, high-performance monitoring of marine resources necessary for a sustainable European economy through developing a new class of underwater imaging LiDAR with 2-3 times larger range than regular cameras and video-rate 3D information

This goal will be reached through six distinct and achievable objectives in terms of Scientific and Technical Excellence (ST) and Market and Outreach Excellence (MO):

ST1) Develop a cost-efficient and compact underwater imaging system capable of capturing high-resolution images at 2-3 times increased range, compared to current underwater cameras.
ST2) Develop the ability to capture full-frame optical 3D data at video-rate underwater.
ST3) Benchmark the technology for applications in biodiversity and seabed monitoring/characterisation.

MO1) Provide a validated prototype underwater imaging system, capable of rapid commercialisation due to extensive use of available components.
MO2) Offer a new and innovative technology platform, together with well-defined exploitation routes, which increases the competitiveness of the European maritime industry.
MO3) Effectively disseminate UTOFIA knowledge within the industrial/scientific communities.
"In the early months of the project, we performed an end user requirement survey and we put together a first prototype (System Zero) based on off-the-shelf components and our own preliminary housing design to test the initial capabilities of the system. By using ""range gated imaging"", the system is capable of seeing through turbid waters. Normal cameras are limited in both range and quality but this principle allows the user to see farther and better. This can enable better identification, visualization and understanding of the measured environment.

We captured images of the target using our first prototype and compared them with a GoPro camera with external green illumination and obtained a better and clearer image at 7.5 meters than the GoPro camera does at 3 meters. This has potential for faster, better and more cost-effective data acquisition subsea.

Using the UTOFIA prototype, we have captured images of schooling fish in an underwater lab facility. By developing algorithms for interpreting the sensor data, we are capable of measuring the distance to different segments of image.
The next step of the project was to demonstrate that UTOFIA could capture not only 3D static scenes, but also dynamic scenes. In preparation for this, algorithms were developed for interpreting the sensor data in near realtime.

A critical element of both range extension and 3D capability is the image sensor used. The project employs two different sensor principles, one courtesy of ODOS and one courtesy of FHG. For the ODOS system, we have worked on integrating a new sensor to replace the current sensor. This should provide faster range gating, increasing 3D resolution and improving range gating. For the FHG system, we have tested a range of different pixel architectures to determine the best one for this applications, and have designed a new sensor with significantly higher resolution and expected performance.

Before testing with live animals, the system had to prove animal safe. The project team had a trial at DTU Aqua (Denmark) which allowed investigating the impact of the laser on fish behaviour as well as capturing 3D information of dynamic scenes in near real-time.
The swimming behaviour was not affected and no measurable stress responses were observed from the heart monitors which is very good news for the further use of the lasercamera in the aquatic ecosystem.

In parallel with testing of System Zero, the System One preparations were continued. Based on the preliminary results from end user requirements survey and the tests performed the initial specifications where revised.
For System One, Bright Solutions provided a new conceptual design for the laser, emitting at 532nm. The laser, specially designed for ruggedness, compactness and reliability has been incorporated into System One, which was built during spring 2016.

The housing have been further developed to provide a compact, sturdy camera frame. Heat management have been specifically taken into account. After testing of the camera system in its frame a compact underwater housing house capable of deep waters (70 – 100 meters) have been designed and manufactured. System One is currently under test.

Throughout Phase 1 of the UTOFIA project, effort has been made to ensure a proper dissemination of project results during and after the project. The website has been set up and is maintained and revised based on feedback. Two news letters have been produced and social media account (Twitter) has been established. The project is presented through different channels like Journal articles, visits to potential customers, direct outreach to journalists and relevant trade shows and conferences.
The dissemination and exploitation plan is currently under revision.
The project has in this period progressed beyond the state-of-the-art by:
- demonstrating a 2-3 times range extension capability of range gated imaging
- showing the opportunities of full-field 3D measurements using time-of-flight technology
- developed two prototypes that that show the system to be compact and cost-efficient

UTOFIA has in the first project period focused on developing two system prototypes which has enabled the consortium to demonstrate the principle and capabilities, and also determine key performance parameters.

These performance parameters have been both technical (in terms of requirements towards the solid-state technologies employed), but also from end-users, who have been surveyed to better understand their needs.

In short, the most important technical requirement is speed (which enables precise range gating and thus better 3D and range extension), and from a user perspective, range extension is the system feature most desired.

Through the first two prototype iterations, the system has been developed to a stage where it is capable of providing a significant range extension, and close-to-realtime 3D imaging. Furthermore, the consortium has demonstrated that the system can become small (< 10 liters), light (< 10 kg) and cost-effective (around 35 k€). These are all capabilities not previously available in state-of-the-art.

In terms of impact, the project will strengthen the competitiveness and safety of the European maritime industry by an innovative and cost efficient underwater camera. The rate and range of 3D information will be better than state-of-the-art and current cost estimate of the system is 35k€. An increased imaging range have been demonstrated, which enables safer marine operation.

The increased quality of data, range of acquisition and simultaneous acquisition of 3D data are now available from the first system prototype. This will provide better data for monitoring of fisheries and pollution, and also support the marine sciences and ocean discovery. This information can not only be used by researchers, but also through good images communicate observations to the general public and policy makers.
First prototype, System Zero
Color encoded depth information based on range gated information
Second prototype. System One, ready for test
Prove animal safe, investigating the impact of the laser on fish behaviour