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TOPIC: Mapping a prehistoric fish pond

Mapping a prehistoric fish pond 4 years 5 months ago #9240

  • mwillis
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Hi, I’m very new to all of this and wonder if you anyone can help make sure that I’m pointed in the right direction.

Here is what I’m trying to do. On the Big Island of Hawaii, there is a natural rocky inlet on the shore that was altered by Hawaiians prehistorically to create a fish pond. Essentially it is a trap that allows fish to enter at hightide and then confines fish to the pool at low tide. The pool is about 200 meters long by 100 meters wide and is 3 meters deep or deeper at certain spots. I want to take a Lowrance Elite 5Ti Totalscan rig and attach it to a small kayak or similar and then move the kayak in transects across the pond recording depth information.

I have a set of Emlid Reach RS RTK GPS units. I would like to attach a rover GPS above the sonar on the kayak and record detailed locational information of each transect.

Here are my questions:
  • Am I crazy to think this will work?
  • Is it possible to link the Reach RS RTK data to the sonar data for processing in ReefMaster?
  • Is there a better way to accomplish this considering that I’m on a tight budget? By the way, I will be collecting photogrammetry data as well.
  • I’m well versed in UAV tech. Is it worth attaching a Pixhawk 1 to the kayak to record the bearing of the vehicle along each transect as well?

  • I
’m concerned about having data from the RTK, 5Ti, and a Pixhawk and not being able to link it all together.

Thanks for any input, suggestions, or insight.

Mark
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Mapping a prehistoric fish pond 4 years 5 months ago #9242

  • Matt
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At the moment it is not possible to link the separately logged GPS data to the sonar log, but this is something we are working on - see lower down in [utl=http://reefmaster.com.au/index.php/forum/support/818-heading-sensor]this thread[/url] for an example (also, incidentally, from a kayak using a pair of Reach units!).
I would say go ahead and record the GPS data in any case as we will be releasing support for this within a few months, and you can use the GPS data from the Elite 5 in the meantime (which is actually pretty decent). Accurate headings are useful if you are recording sidescan but probably not hugely significant otherwise, especially if you are not applying a distance offset to your transducer.
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Mapping a prehistoric fish pond 4 years 5 months ago #9246

  • mwillis
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Hi Matt, I really appreciate your reply and expertise. Two things, I was hoping to send the RTK corrected signal directly to the Ti. So far I haven't had success with that over a wireless connection. Sounds like I might be wasting my time... You mentioned elsewhere, " E.g. Lowrance units log position to approximately 1m resolution.". Does that mean I won't increase my resolution much/any by adding RTK?

Is the depth signal that's written to the Ti SD card accompanied with a GPS timestamp? If so, would it be possible to brute force match it to the RTK data?

Thanks again,

Mark
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Mapping a prehistoric fish pond 3 years 1 month ago #10591

  • PauG.
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Hi Matt,

After this time, I'm curious if it's now possible to use an elite 5 ti and a rtk system working with reefmaster livedata.

I'm working on a remote survey boat with pixhawk

Thanks in advance
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