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Old 27-03-2012, 03:21   #1
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Hydrographic Survey Plugin

Howdy...
The idea of a plugin able to record and display sounding data appeared a couple of times in the past, so here's a prototype implementation.

Currently the plugin is very simple - it records all the soundings that come reasonably close to a position fix (thanks to SethDart for the code I as usually cannibalized from the dashboard) and draws them as a more or less configurable overlay.
The logic is currently totally unoptimized, so don't expect miracles. There's also no functionality allowing you to organize the recorded data implemented - get spatialite-gui to play with the data at database level (look for survey.sqlite in the same place where your config file is).

Don't worry that you sit in your armchair and don't have an NMEA stream available - the prototype comes with a little testing dataset at 037 52.4031 N 122 18.8240 W

TODO for a reasonable future:
  • Sensor (sounder/GPS) offsets to achieve the best possible accuracy
  • Performance tuning and display optimization (not much sense to draw all the recorded soundings while at 1:100000 scale etc.)
  • Basic data organization functions
  • Integration with TeamSurv
  • Whatever you suggest

The plugin uses the excellent spatialite library as it's storage backend. It means you can very easily get the data to pretty much any GIS system and you can work with the data directly using standalone SQL tools (Look at https://www.gaia-gis.it/fossil/spatialite_gui and https://www.gaia-gis.it/fossil/spatialite_gis).

The Windows build is available at https://github.com/downloads/nohal/s...01_pi17_pi.dll (Perhaps, if not already available on your system, you will also need https://github.com/downloads/nohal/survey_pi/iconv.dll placed in your OpenCPN program directory) - Remember that you need OpenCPN 2.6.1524 for this thing to run.
Source at https://github.com/nohal/survey_pi

As usually any contributions and ideas are more than welcome. If someone feels like wanting to try to code something for OpenCPN, this is an ideal opportunity - the code is really very simple at this point.

Pavel
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Old 27-03-2012, 05:53   #2
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Re: "Hydrographic survey" plugin

Hello Pavel,

Yes, I alm in my armchair .... But where are the data set that you said in the post ?

B.R.

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Old 27-03-2012, 05:55   #3
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Re: "Hydrographic survey" plugin

Gilletarom...
The testing dataset is hardcoded into the plugin - it inserts the values while initially creating the database. You should see exactly what's on my screenshot if the plugin works.
If not, send me your logfile from the last run.

Pavel
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Old 27-03-2012, 06:19   #4
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Re: "Hydrographic survey" plugin

Pavel,

Quote:
Originally Posted by nohal View Post
Gilletarom...
The testing dataset is hardcoded into the plugin - it inserts the values while initially creating the database. You should see exactly what's on my screenshot if the plugin works.
If not, send me your logfile from the last run.

Pavel
I saw nothing!

OpenCPN it was your view navigation area?

But beware, this may be a bug of 260-1524 because when I try to run the new version of VDR SethDart send to me, the chart does not move.

B.R.

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Old 27-03-2012, 06:26   #5
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Re: "Hydrographic survey" plugin

As posted above: 037 52.4031 N 122 18.8240 W - I see no problem with the VDR plugin in 2.6.1524 - works well when I use it with http://www.navmonpc.com/Downloads/PacCupStart.txt to test this work actually.

Pavel
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Old 27-03-2012, 09:56   #6
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Re: "Hydrographic survey" plugin

Pavel

good start!
A couple of things come to mind (unsorted ramblings.....)
  • tide correction. TeamSurv does an offline correction of the data, fine for them. But for real-time use on the boat, tide data from a near, selected station should be used to correct. And/or manual input of tide.
  • An import of depth data from the S57/CM93 charts, to have the database filled for a given area, then add/correct from actual measurements (Maxsea does this)
  • Use of measured data, combined with vector chart data!?) in opencpn, not just waypoints with depth-"names". Example: when fishing/trolling, I would like to see the vector chart continuously updated, so I can run over missing data-points to get a visual of the bottom structure.
  • "future" proofing the data: always keep the raw data in the database, tide correction, depth of transducer, or any other correction separate, to redo a final result if needed

Thanks!

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Old 27-03-2012, 10:08   #7
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Re: "Hydrographic survey" plugin

Things to observe while taking data -
a link from the Schottish guys SailorF54 mentioned:

Making the charts

And if you are using a portable GPS (and perhaps some of the GPS mice as well):
observe what happens with SOG at very low speed. There are GPS that interpret a speed of 0,1 or 0,2 knots as stillstand - to avoid noise when you are really "parked" with your car or bike. This will lead to wrong geographical references or jumps in your data.

bcn
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Old 27-03-2012, 11:11   #8
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Re: "Hydrographic survey" plugin

Folks....

I love this idea.

Re data accuracy:

Reducing to state of tide nearby seems questionable to me. We have seen many cases of tidal database corruption. There is no traceability on many of the tide stations we will need, and they are few and far apart in the "good" cruising grounds.

Statistically speaking, if we can get enough data at a specific point, then we could argue that the mean depth reported is actually the true depth at mid-tide, regardless of the quality of any one input sounding. Need lots of data, and some evaluation of the std deviation in order to get confidence with this methodology.

Mathematicians will recognize this as a variation of the "Central Limit Theorum".

Another idea:
OCPN could display the assumed quality of crowd-sourced soundings in colors, or gray scales. More data presumably means better data.

Just thinkin'
Dave
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Old 27-03-2012, 11:49   #9
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Re: "Hydrographic survey" plugin

Hey Nohal,

This is an outstanding value piece of functionality. We could survey an area before overlaying the results on our charts to be used for getting into some anchorages.

Pita we did not have it during our Pacific trip.

Great idea! THX for your efforts!
b.
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Old 27-03-2012, 23:22   #10
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Re: "Hydrographic survey" plugin

I like the idea
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Old 29-03-2012, 12:06   #11
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Re: Hydrographic Survey Plugin

Pavel,

That's beautiful!

When I get time in the future (probably Fall/Winter), I will try to make some surveys with the tool and experiment with using some tools to generate contours and tidal corrections into a raster/kap format. Then testing the overall accuracy.

If in the meantime you find time, perhaps you could show others how to use it with other applications and GIS tools. And maybe having the ability to submit soundings to on-line databases that are out there.

Great work!

Eric
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Old 29-03-2012, 13:04   #12
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Re: Hydrographic Survey Plugin

Really useful idea! Lots of places I have been are completely uncharted.
In addition to the above suggestions, once the data is "in" it would be nice if it could draw contours.
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Old 29-03-2012, 14:18   #13
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Re: Hydrographic Survey Plugin

Very nice, Pavel. Does the dataset also record current time of day (local or GMT) and, if available, any tidal station data? Those would help correctly offset the depths from tidal changes when the data was processed.
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Old 31-03-2012, 11:21   #14
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Re: Hydrographic Survey Plugin

It would be difficult to implement in the plugin a function whereby data typing high and low tide site officers have the tide at all times?.

Sorry for my bad English
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Old 03-04-2012, 13:03   #15
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Re: Hydrographic Survey Plugin

Hi all..

Now THIS sounds like what you are looking for:

Quote:
Eye4Software Hydromagic
Hydromagic is a GPS Mapping Software package designed especially for use on hydrographic survey vessels, dredging vessels or research vessels. The software allows you to record your current depth on the map using only an echosounder and GPS device. Recorded tracks can be post-processed or exported for further processing.
Download 30 day free trial:
http://www.eye4software.com/files/hy...etup_hydro.exe

Tore
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