Відео

Yes, it is indeed! Thanks for watching.

Hello, thank you for your question! It is important to know the draft of the transducer if you are using a tide gauge to correctly georeference the depths measured to the relevant datum. In our case, the tide correction is done with RTK GNSS, so the draft itself is not important but the offset between the GNSS antenna and the transducer is used instead. I hope this helps!

@@ExoEnvironmental thankyou sm sir..really appreciate for the ans

We use software called Teledyne PDS which handles all of the processing in-software. We also use RTK GNSS throughout the survey to correct for the tide as that is much more accurate than using tidal gauges. The chart datum (typically LAT) can usually be obtained from navigational charts or the local authority depending on location. The Z correction is then applied on the measured GNSS data. Hope this is helpful!

@@ExoEnvironmental it's ok. Thank you, But can you make this a little more detailed.. if you have sketches or videos where this is done that will be more helpful.

@@ExoEnvironmental is there any number or email I can contact to have a detailed discussion.

​@@nsikakobongeyakz4032 The methodology depends on the exact equipment used, which makes it hard to produce general tutorial videos on specific equipment / software. These should be available from the manufacturer. Feel free to take a look at our website for more information of Bathymetry (exo-env.co.uk/bathymetry/). You can send an email through our contact page!

@@ExoEnvironmental thank you so much

Do you mean the minimum number of pings/measurements per unit area? That would depend on the depth/level of prevision required (i.e. IHO special order)

@@ExoEnvironmental yes thank you for your timely response

​@@dhanushjayakumar537 No worries. In one of our recent surveys in a shallow water environment (<3m depth), we covered the area with an average number of 14 pings per square meter. This was done with a single beam system so this is the number of measurements directly below the survey lines. Those are spaced very closely together (between 5-15 metres), depending on the topography of the bed to allow for accurate interpolation.

Hello! Good question! There are many controls to ensure the accuracy of the survey. Unlike ground based measurements which remain positionally fixed, positional accuracy on the water is somewhat difficult to pinpoint to such a level of accuracy, especially where there are tidal influences. In order to achieve the best quality data, RTK GNSS positioning system is used with a reference base station on a known point. This provides cm accuracy throughout the survey at sub second intervals to correct for things like tide or heave. The other aspects of measuring the depth have a lower accuracy overall (the sonar) and are therefore the limiting factor. In those aspects of the bathymetric system, accurate calibration of the echosounder and measurement of the sound velocity in the water both before and after the survey are essential. Lastly, the survey is performed with overlapping survey lines to allow for comparison of the final calculated depth at locations where the lines intersect. This allows positional quality control across the entire area, not too dissimilar to a levelling traverse procedure. Hope that helps!

Glad you're enjoying them, stay tuned!

Hello! The echosounder is able to function correctly up to a depth of 50cm. Any shallower water and the echosounder will actually pick up the internal casing, and subsequently produce too many errors. In a tidal environment shallow water is surveyed at low tide with drone photogrammetry. Whilst shallow static water bodies will have to be surveyed by topographic survey pole. All three types of data collection can be merged in our software, to create one chart, map or model.

Hi! If you want to achieve the highest order of accuracy then yes you should use a dedicated motion sensor, however in shallow waters and calm conditions the effective error of not using one is negligible. The positioning system (GPS) also corrects for tide and the heave of the boat. Hope that helps!

Exo Environmental Thank you, great informational videos!

Thanks!

Hi Mohamed, one idea would be to look at The Hydrographic Society website, they have a page full of relevant courses!