The Canadian Hydrographic Service (CHS) and Teledyne Caris conducted two important sea trials in July and December of 2015. The July trial was to test the capabilities of Caris Onboard for near real-time processing, while the December trial was focused on remote access to the products created through a remote survey operation.
Caris Onboard is an automated service installed on the survey platform that monitors raw data files from an acquisition system. As new data is detected, it is automatically processed using a customised workflow which can include converting the data to a HIPS project, applying tide and sound velocity corrections, and producing products such as surfaces and sonar image mosaics. Processing status and progress are monitored through the web application “Control Centre”, while the products and quality information generated by the onboard service can be streamed to a Caris desktop applications. This enables the hydrographer to view the geo-referenced survey in near real-time from a remote location for quality control and decision support, while the survey is still underway.
CHS Atlantic – July 2015 trial
Teledyne Caris and CHS organised a trial for Caris Onboard during a survey of the Wood Island Ferry Route in July 2015. The survey consisted of EM2040 dual head data collected from the CCGS Frederick G. Creed. The main goal was to test the service and ensure it produced the expected results.
During standard operations on the FG Creed, once the acquisition system has released a line the survey crew manually copies the file to a separate drive. When the data processor sees the new line appear they manually run it through the following sequence of processes:
Fig. 1: The workflow diagram for the service.
The initial workflow allows quality control on the data to occur during operations, allowing problems in acquisition to be identified and corrected before the survey is completed. To test Caris Onboard, the software was installed on an independent computer, to not interfere with normal operations, and the same initial workflow was applied. However, the service was able to directly monitor the acquisition computer for the raw files.
As each file was finished, the software automatically imported the raw data into a HIPS project and applied all the processing steps which are required for the initial quality control to occur. Not only did the software ensure the data was available for quality control in the fastest possible time, but it also freed up time for both the acquisition and processing teams, allowing them to focus more on mission critical tasks.
As the software is automated, it reliably applies the same pre-configured workflow to each file as per operational procedures, removing the possibility of human blunders. The software freed the processing team from having to spend their time on mundane tasks, and allowed them to focus on processing the navigation data, reviewing the survey quality, and moving the processed data further along in the workflow. Ultimately, it minimised the remaining processing backlog for when the project finished.
The acquisition team was no longer distracted by copying each file as it finished, allowing them to focus on running the survey equipment. By having real-time access to the Cube Surface on the bridge, the surface could be quickly reviewed for systematic errors that had adverse effects on the data quality. Or by using the standard deviation, total propagated uncertainty (TPU) and data density layers they could easily note when the line spacing required adjustment or when a section had to be re-surveyed. Ultimately the survey quality feedback loop became much smaller than the traditional method of waiting on the manual processing.
To ensure that the software was producing the same results as the manual processing, a three dimensional comparison of processed depths for individual soundings was performed. After all processes have been applied, the processed depths consist of the latitude, longitude and depth value for each sounding. The comparison showed that all soundings matched to the full stored precision, which is 1 mm for depths and 1/10000 of an arc second for latitude and longitude.
A comparison of the generated surfaces was also performed using the Difference Surface function in HIPS and SIPS. As the Cube function is dependent on the order that the lines are added to the surface, care was taken to ensure that only a single line was added at a time, in the order they were acquired. The difference surface produced from this test showed a minimum and maximum value of 0,000 m, confirming that the two workflows produced identical surfaces.
CHS Pacific – December 2015 trial
Teledyne Caris and CHS also organised a joint trial focused on the remote access capabilities of Caris Onboard. This would demonstrate that the software would be a viable solution for allowing the quality of data collected, without a hydrographer onboard, to be reviewed remotely. The survey consisted of R2Sonic 2022 data being collected by the CSL Shoal Seeker.
The December trials had two main goals. First was proving that CARIS Onboard could supply reliable access to the Cube Surface over a 3G connection. Second was validating the performance of the overall survey system, which included real-time global navigation satellite system (GNSS), using a previous in-time sound velocity correction, and the software.
Fig. 2: View of the system running on the FG Creed. Left on the screen is control centre, used for monitoring the processing progress. Right on the screen is Caris Easy View connected to the live updating Cube Surface.
The CSL Shoal Seeker was mobilised with two computers. The first computer was interfaced with the survey equipment and was used to run the acquisition software, while the second computer was setup as the processing box, and was connected to the acquisition computer through a local workgroup. To provide remote access a Telus 3G wireless mobile internet device was connected to the processing computer. Caris Onboard was installed on the processing computer, and was able to monitor the raw data directory on the acquisition computer. As each line was released by acquisition, the software detected that the line was complete and submitted it through the following workflow:
Fig. 3: Equipped with an R2Sonic 2022, Applainix POS MV and AML Oceanographic Minos X (SVP), the CSL Shoal Seeker provided an ideal platform for testing the service.
By using the 3G connection to serve the Cube Surface over the internet, it was available for use on the survey vessel as well as being available for review from within the CHS Pacific offices while the survey was ongoing. As the entire Cube Surface was made available over a remote connection, the hydrographer in the CHS Pacific office was able to connect to the surface using Caris Easy View, while loading background information to give the survey context. The hydrographer was also able to query the various surface layers, such as density and standard deviation to quantitatively and qualitatively review the survey results.
While the survey was ongoing, the hydrographer was able to extract from the remote connection that the vessel speed was too fast. He immediately made contact with the vessel crew, requesting they reduce the vessel speed to improve the along-track sounding density. The unintended event actually turned out to be exactly the results that the CHS was hoping to see, as it proved that the software allowed a remote hydrographer to review survey quality and initiate changes in how the data was being acquired, while the survey operations were still underway.
To validate the performance of the overall survey system, including Caris Onboard, the trial survey was carried out over the test bed in Patricia Bay, which includes a series of ten concrete blocks ranging from 0,5 m to 1,0 m in size. The blocks were placed in water depths ranging from 16,6 m to 37,2 m in 2011 as part of a collaboration between CHS and The Naval Oceanographic Office [1]. Over the course of several surveys the position of the blocks had become well established, so for the purpose of validating the real-time system the positions were considered to be known. The detected positions of the targets in the real-time surface produced by the software were compared to the known positions, determining whether or not the system could detect and position the targets within IHO special order standards.
Fig. 4: Simultaneous viewing of the processed survey data, both on the vessel (left) and in the CHS Pacific offices (right).
Given that the results are produced in near real-time, using sound velocity with a previous in-time algorithm and real-time GNSS, the comparison provides a reasonable representation of the level of uncertainty that could be expected. Although this method does not directly demonstrate the TPU for the system, the positioning of all ten targets within IHO S-44 special order standards is a good indication that hazards to navigation can be reliably identified and reported through a Notice to Shipping or Notice to Mariners, based purely on a remote connection to the real-time surface being produced by Caris Onboard.
|
Target # |
Target size (m) | Horizontal diff. (m) | THU (m) | Vertical diff. (m) |
TVU (m) |
|
1 |
0,5 |
0,106 | 2,000 | -0,096 | 0,280 |
|
2 |
1,0 | 0,459 | 2,000 | 0,134 | 0,291 |
|
3 |
0,5 | 0,352 | 2,000 | 0,114 | 0,289 |
|
4 |
1,0 | 0,575 | 2,000 |
-0,002 |
0,293 |
| 5 | 0,5 | 0,495 | 2,000 | 0,098 |
0,291 |
| 6 | 0,5 | 0,432 | 2,000 | 0,072 |
0,287 |
|
7 |
1,0 | 0,454 | 2,000 |
0,016 |
0,364 |
|
8 |
1,0 | 0,158 | 2,000 | 0,174 |
0,372 |
|
9 |
1,0 | 0,398 | 2,000 |
0,114 |
0,374 |
|
10 |
1,0 | 0,502 | 2,000 | 0,134 |
0,371 |
Conclusion
Remote access and the use of autonomous survey platforms are outside the normal scope of current CHS operations. Without a means to process the data on the platforms during or immediately following acquisition, these types of operations will begin to form a processing backlog, creating several negative effects. It could cause detected hazards to remain unidentified for several months. Not having a feedback loop could have serious implications on the quality and quantity of the survey production.
Also, if the delay between acquisition and production becomes too long, it could discourage the essential cooperation by the crew aboard a survey vessel. By automatically processing the raw data on the survey platform in near real-time and making the surfaces available over a remote connection, the concerns related to the lack of feedback loop and ever increasing processing backlog diminish.
Through the use of software such as Caris Onboard, the platforms will return from their surveys with datasets that are partially to fully processed, depending on the overall workflow. Additionally, by making use of the remote connection the data can be reviewed while operations are underway, maintaining a feedback loop even without a hydrographer on the vessel.
Acknowledgements
The authors would like to thank CHS Pacific for assistance with Shoal Seeker mobilisation and data collection, and CHS Atlantic for assistance with FG Creed mobilisation and data collection.
References
[1] R Hare et. al: Establishing a multibeam sonar evaluation test bed near Sidney, British Columbia, Proceedings of the Canadian Hydrographic Conference 2012, Niagara Falls, Canada, (2012).
Contact Kimberley Holland, Teledyne, kim.holland@caris.com
