Webinar | Drone bathymetry & data processing for single and dual-frequency echosounders

Introduced by SPH Engineering in spring 2020, 'UAV+echo sounder' integration has become in high demand for mapping, measuring, and inspecting tasks as well as environmental monitoring of in-land and coastal waters.

A UAV drone equipped with a single or dual echo sounder allows to collect data with high accuracy faster due to easy transportation and fast deployment and it is 2 times more cost-efficient compared to the traditional methods. It has the ability to operate at hard to reach locations, unsafe or hazardous environment. Locations not reachable by foot or dangerous for a human (steep coasts, mining pits, contaminated waters, terrain obstacles, etc.) as well as waters of ponds, lakes, and canals can be reached by a drone.

What you will learn: 

• Overview (system components, application workflow)
• Data processing of single and dual-frequency echo sounders in Hydromagic - demo using samples from real surveys.

Q&A

• Q: As I listen in, I'm wondering if you can address why we would use drone bathymetry instead of boat based systems? Also, what water speed this system is effective for?
  A: Reasons why a drone should be used instead of a boat were answered live - but in short - for application scenarios when a boat-based system can not be applied - drone-based system is a great solution. Will also answer the question about water speed in the live Q&A.
• Q: How is radar altimeter better compared to using LiDAR range sensor for altitude control?
  A: From our experience when flying over water a radar altimeter is more accurate than laser altimeter because reflection from the water surface can throw off the laser altimeter.
• Q: Does the echo sounder have a PSI sensitive release ring, which releases the sensor if an exceeding force is applied downwards? (I fish grabbing it or other Gravity force)
  A: It does not have a release ring, the echosounder is quite heavy and is used near the surface of the water. We haven’t come across this necessity yet. But it’s a good idea!
• Q: Any salvage devices for unanticapated stuck by water plants?
  A: Usually the lift power of the drone is sufficient to get the echosounder unstuck. Additionally, the weight of the echosounder also helps.
• Q: What is the minimum depth for accurate measurement with echo sounder?
  A: Single frequency echosounder - 0.30 m, dual frequency - 1.15 m.
• Q: Does Skyhub ingest the GPS data from the autopilot, or do you need a secondary GPS specifically for the echosounder?
  A: You do not need a secondary GPS, SkyHub is ingesting the GPS data directly from the autopilot. But you can choose to use a secondary GPS onboard (such as Emlid) and use this data in processing.
• Q: In the pond example, is the ecosounder being dragged underwater in the mission, or would less energy be used if you pop in and out of the water?
  A: Usually it is more efficient to drag it, otherwise you will need to use more energy to stop and go at each point. But we also do have a grasshopper mode that allows you to pop the echosounder in and out.
• Q: Which software do you use for data processing?
  A: We use Eye4Software Hydromagic Survey
• Q: Power for components come from main M300 battery or self contained battery on the components? if off the main DJI M300 battery how does it affect endurance time?
  A: We are using power from the battery of the drone. It does not affect endurance as significantly as the weight of the payload.
• Q: Is the hydromagic survey software included in the purchase of the echo sounder?
  A: Yes, it is!
• Q: Can you use the tilt angles to correct the echo sounder data, and thereby speed up scan?
  A: Theoretically you can but the resulting data will still be less accurate than when flying at 0.6 m/s. So we do not recommend it.
• Q: What is the typical cost of a system excluding the drone?
  A: Please contact our Sales team by email ugcs@ugcs.com
• Q: Is there an online sound velocity probe integrated with the echo sounder?
  A: We don’t have a sound velocity probe integrated with the echosounder.
• Q: Does the hardware run on any other drones besides the M300?
  A: Yes, you can use it for example on DJI M600 or even on Pixhawk-based drones.
• Q: How much does Hydromagic software cost?
  A: Hydromagic software is not product of SPH Engineering.
• Q: I see that the position of GNSS Antenna is different than the position of Echosounder. Do you correct this offset?
  A: This offset can be corrected in Hydromagic, yes.
• Q: Hello, has it been tested in port environments? Thank you.
  A: Yes, it has been tested by our customer in Israel.
• Q: Hi, what is the lower height possible to measure?
  A: Single frequency echosounder - 30 cm, dual frequency echosounder - 1.15 m.
• Q: Is it possible to measure bathymetry without mission planner ?
  A: Yes, data is also recorded during manual flight.
• Q: What is the ping rate of the echo sounder and roughly, how many of those measurements are meeting the requirements in regards to roll/pitch to be used in the final product?
  A: Discover more data here »»»  
  Roll/pitch angle can be defined by the user.
• Q: Is there a minimum and maximum depth you are able to accurately scan using this system?
  A: Hard maximum depth is 100 to 200 m based on which echosounder you are using. Minimum - 0.3 to 1.15 m based on which you are using.
• Q: Do you measure the sound velocity of water prior to flights, or do you use default values for salt/fresh water?
  A: We are not applying this ourselves since the difference will not be that big with shallow waters but some of our partners are using sound velocity profilers.
• Q: Is it possible to use D024 echosounder ?
  A: Yes, it is possible!
• Q: I would think if there is debris in the water you could possibly snag the sounder. Has that ever happened?
  A: For water bodies that are overgrown, you can use the grasshopper mode to make point measurements rather than having to drag the echosounder through.
• Q: What is the max angle off vertical that you would accept/reject?
  A: This can be set in the configuration file of the system.

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