Hydrographic surveying

Hi.

Is there anyone out there who can recommend the appropriate drone & camera/surveying set-up to enable me to survey the bottom of lakes, ponds, rivers & marinas from the air rather than using sonar dragged by a boat?

Much as 3D mapping works above ground to calculate the size of an area, height of hillside etc. I want to do the same underwater.

Any advice would be very welcome.

Regards

Paddy

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  • Take a look at SimpleUnmanned's boats. They're pixhawk based so skills should cross over well. 

    www.simpleunmanned.com

  • Thanks Robert,

    Keep in mind that what systems I can't have on board I can easily tow.  I have towed a Ocean Kayak with a 180 pound person in it at 2 Knots only using 40% throttle .  The Reefmaster Suite of software works very nice.  My point was I can tow "legitimate survey equipment" as needed.  My boat is a bit like a tractor and will do what ever is asked of it. Some times renting equipment as needed is better than owning.  Have a great evening.

    Regards,

    David R. Boulanger

  • Hi David (and Paddy) - 

    Nice setup! Great point - Of course, you can strap sonar to anything that floats and use pixhawk as a control system. I'm sure it works fantastically for general assessments. I guess it depends on who your client is and what they are willing to accept in terms of accuracy. For a small project on a drainage reservoir at a water park, this would be perfect. But in my example with the army corps of engineers surveying a dam for demo, no way. You must do this in tandem with legitimate survey equipment. The rental of the equipment for 3 days alone costs more than the construction of that craft. 

    How are you running/integrating your GNSS RTK system? If only it were easier to use underwater GCP's! :) 

    These are the crafts that I am most familiar with http://oceanscience.com/Products/Z-Boat/Z-Boat.aspx

    Running hypack works very well and integrates nicely with most professional software systems. 

  • Robert Blank,

    I disagree with you that Drone Boats are $30,000 + and have little overlap with the UAV systems we are most familiar with.  This boat uses a Pixhawk, RFD 900, FPV, Antenna Tracker and Mission Planner.  Currently using the latest Ardupilot Rover Code.  I will sell it however for $30,000.

    Regards,

    David R. Boulanger

    boat pic.JPG

    Screenshot (3).png

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    https://storage.ning.com/topology/rest/1.0/file/get/3702283418?profile=original
  • Hi Robert & many thanks for your input.

    You seem to be saying what everyone has said so far, in that there just isn't the technology out there at the moment to perform underwater surveys from the air so unless invest huge amounts of time & money I guess I'll just have to wait a bit longer to see if anything comes onto the market.

    Thanks for your help.

    Paddy

  • Hi Paddy - 

    As much as I want to give you aerial options.. I would rather save you some time! Our team has done months of research on this topic doing water supply assessments based on snowmelt and reservoir volume. 

    The short answer is no - hydrographic surveys are most effectively conducted using types of sonar. The reason is because trying to read an accurate measurement of a signal traveling through air.... -> water + particulates + turbidity can heavily distort your data. However, aerial can be highly effective when accompanying hydrographic because depending on the nature of the mission, you will likely need to capture topo from the shoreline. For example, somebody like the army corps of engineers may want a volumetric assessment of "full pond". This includes the shoreline topos. Anything over a few feet deep in moderately clear water is going to be very tough. Optical solutions are not the tool for the job. 

    Additionally, you will need GCP's if you are doing a survey of any engineering quality. This will likely entail having a survey team on the ground anyways if they already have iron set in the area. 

    The long answer is that you should be able to find solutions using certain forms of radar with heavily modified and highly specific parameters to correct for the water/air interface. You will pay big bucks for this though and it is far from an "off the shelf" product. A partnership with a research institution or an intimate understanding of the technology is required. 

    There are boat drones available from some companies but we found that unless your company is exclusively focused on hydrology, you will see greater fiscal returns buying a $1,500 aluminum jon boat, a trolling motor, and renting a survey unit for each mission. The boat drones are like $30k+, rather large, and there is very little overlap with the UAV systems we are most familiar with. Additionally, you will need separate software to process the sonar readings. 

    Hope this helps. I'm happy to chat with you about this in more detail if you would like!

    - Robert

    Mountain Drones

  • Developer

    You might want to take a look on Tom Coyles builds in the ArduBoat group :)

  • if you were to build a Arduboat, high end "fish finders" can do amazing resolution with new types of "ping" sonar and create surface geolocated surface models in real time.

    Ill bet if you build it they will come....asking for bathymetric surveys.:)

  • A lower frequency laser at about 532nm will penetrate the water surface.  So look for a lidar system that is a lower frequency than the standard 905nm.

    I don't know if there's one available commercially for UAV's but that's what you'd use from a manned plane.

  • Thanks Pascal.

    I realise now that my idea was a bit optimistic but I'm still going to pursue the idea, possibly of towing a small piece of sonar equipment mounted on some form of raft to reduce the drag factor.  Have you seen this done before?  Obviously drones pulling things isn't ideal but there must be a way around this.
     
    Pascal P. said:

    No way to do this with camera only. There is a possibility from airborne laser for shallow water, but this thing is so heavy for a drone, I only heard of real plane doing that. Echo sounder is still the only way to go.

    I do drone mapping and also bathymetric survey with multi-beam echo sounder and the typical gap is 0 to 2-3 meter depth where it is too shallow for the boat, and not visible from the sky.

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