AltoMaxx: Drone-Based Bathymetry

[@patstack67]

Assuming that the drone is where the GPS position is taken, how do you account for the horizontal difference in the position of the drone versus the position of the sensor. This would be particularly critical in a stream where the echosounder might be horizontally offset by several feet.

[@jdsagona]

My first thought as well, I would love to hear an answer to this.

[@bosanova1643]

I believe you are asking too much. There is surely an answer. However, for those like me who have experienced the traditional bathymetry of hard labor on a poor little leaking canoe, I can assure you that this system has the merit of existing! :D Next, regarding the sensor's offset, the calculations to approximate its planimetric position don't seem too complicated. You know the tether's length, the z-coordinate of the drone, and thus the z-coordinate of the water at the time of immersion, etc. But indeed, we can see the infamous 'saw teeth' on the slopes in the renderings, which clearly show the disregard for horizontal offset. By using a clean slope or a regular launching ramp, and by making a round trip in the direction of the slope, we can very easily recover the towing offset constant.

[@altomaxxtech]

Thanks for your question! The drone is indeed where the GPS position is taken, so the sensor where the data is recorded may be offset somewhat. However, there are several ways to reconcile this discrepancy. Firstly, the drone is pre-programmed to fly at a set height above the surface, and the sensor is attached to a tether with a known length. Secondly, there is a tilt sensor attached to the echo sounder that records its angle relative to the y-axis for each data point. This tilt angle is used during post-processing to remove data points where the sensor tilted too far, or to calculate and correct the horizontal offset of the GPS location. You can read more about it in this whitepaper: integrated.ugcs.com/files/bathymetry/bathymetry-using-uav-accuracy-concerns.pdf

[@wallopthecat]

Do you use any GNSS reference systems on ground to fix gps drift?

[@swanthorn]

looks interesting!

[@therealclassicreuben]

Current or weather not a problem, sure, but what about marine debris... logs and deadheads for example?

[@altomaxxtech]

The bathymetry sensor is tethered to the drone but is only submerged approximately 9 inches while collecting data, making it less likely to hit debris that is submerged beneath the surface. As well, there is a “grasshopper mode” where the drone dips the sensor at select points rather than drags it through the water. This might be an option if debris is a concern. If you have other questions, feel free to reach out! www.altomaxx.com/contact-us/

[@HydrographicSurveyor]

amazing 👏👏

[@eprohoda]

enjoyed! that's outstanding , do you want more followers?! all the best.fellow,✋