Topic: Hi Matt - can this be done as I envision it?

[Geno]

I will be doing masters work for the next two years and a lot of my work will be with sonar. The university has kindly agreed to provide me with funding to build a system that can remotely sense and map the bottom of the local river in such a way that it can be integrated with arcGIS with the understanding that I leave it behind when I move on to PhD work.

Fluvial geomorphology is my focus and our ideal situation will be the ability to record bedload (bottom sediment) movement in a semi-dynamic environment and the holy grail will be the ability to determine different types of bottom sediment in a short range freshwater  setting (our smallest environment will be a creek fifty to one hundred feet wide and five to thirty feet deep, our largest will be an impounded river several hundred yards wide and up to 150 feet deep).

My intention is to use an 800 series (smallest networkable) unit with an LSS2 transducer (much sharper image as far as I can tell) hull mounted for the small waters and towfish mounted for the larger waters, networked to a laptop with a huge hard drive running some sort of freeware or low cost mapping integration ware for the sonar, I have an older Trimble  differential GPS that I hope I can use for location.

[matt@reefmaster]

Hi Geno,
Yes, you should be able to do much of that using ReefMaster. We have a bottom-composition module that creates E1 and E2 (roughness and hardness) layers which can be exported as Shapefile polygons for use in ArcGIS. Also the bathymetry can be exported in the same way, or as an ESRI grid for further processing in ArcGIS or other applications. At the moment RM cannot get bottom hardness data over the ethernet - we only support NMEA 0183 for live mapping (which only has position and depth data), so for bottom hardness and sidescan you would need to record your sonar data to an SD card before processing it in RM. This might preclude the use of your separate GPS when recording bottom-type and sidescan data for use in RM, unless you can get that signal into your HB unit, but the GPS on the unit is probably good enough for your needs.
Another issue might be correcting for location with your towfish - we do have transducer location offset settings, but the relative position to the boat is not going to be constant during turns - although you can mitigate this by doing straight runs.
We also have a sidescan mosaic module due for release around the middle of this year.
I would recommend downloading the trial and seeing how you go, and then coming over to our forum where there are plenty of mapping enthusiasts - you will get a quicker response to your questions there.

cheers,
Matt

[Geno]

Thanks so much Matt.

The gps in the unit may indeed be sufficient for my needs - I have to play around with one first to know.

I can do all of our mapping with straight-ish runs if need be for closer correction when using the towfish - no problem there. The towfish use will most likely not be to get the transducer closer to the bottom though. My intent is to use the towfish for cleaner images...to reduce the amount of wave action at the transducer so the setback or offset should be relatively short. I am currently at a loss as to how to make long cables for the fish anyway.


I am putting this system together with a target date of May 2014 for the initial testing, so I am looking forward to your mosaicing module.