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Getting the community soundings data from C-MAP Social Map Data

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Created by Achernar 1 month ago, 28 Jun 2022
Achernar
QLD, 329 posts
28 Jun 2022 8:16PM
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This is a question for the data-geeks here.

C-MAP Genesis Social Map allows community subscribers to upload soundings from their chart-plotters, which can then be downloaded by other subscribers as charts for use in their chart-plotters. It is a nice example of crowd-sourcing, which also means that the odd corners of waterways can get mapped by anyone intrepid enough to sail into them with the right gear.

What I would like to do is not to download the charts, but to download the data. The data format would be point cloud, possibly DEM, or whatever. I would then input the data into a GIS platform on a PC (I'm using QGIS) to generate a surface of the river-bed or sea-bed. The reason is that I would like to get the bathymetry for particular reaches of navigable rivers, or lakes.

For instance, I have found that the C-MAP Social Map data includes a reach of the Wilsons River downstream of Seaham Weir. Although I can see it on-screen, and there is an option to output it as a chart to a chart-plotter, I really want the data from which the chart is generated. Also, I don't have a chart-plotter.

NB I use terrain data a lot in my line of work as a hydrologist and civil engineer. The ELVIS Elevation Data Portal curates the publicly available data, such as the high-resolution digital elevation models (DEMs) derived from LiDAR surveys, which I find invaluable. However, these surveys do not extend below the water surface, which means that if I need a river-bed, like the Wilsons River, I need to look elsewhere, or pay for a survey. Hence, the question.

tarquin1
792 posts
29 Jun 2022 2:44AM
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Navionics has relief shading. Not for all areas. Find someone with a subscription and see if the area you want has it.


Don't have Oz sorry.

woko
NSW, 1214 posts
29 Jun 2022 7:13AM
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Not cmaps but the sonar phone sounder and navionics app will create a chart, cheaper than a survey. I use the above to chart tucked away places haven't updated my subscription for years so the info hasn't been uploaded

shaggybaxter
QLD, 2415 posts
29 Jun 2022 6:13PM
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Select to expand quote
Achernar said..
This is a question for the data-geeks here.

C-MAP Genesis Social Map allows community subscribers to upload soundings from their chart-plotters, which can then be downloaded by other subscribers as charts for use in their chart-plotters. It is a nice example of crowd-sourcing, which also means that the odd corners of waterways can get mapped by anyone intrepid enough to sail into them with the right gear.

What I would like to do is not to download the charts, but to download the data. The data format would be point cloud, possibly DEM, or whatever. I would then input the data into a GIS platform on a PC (I'm using QGIS) to generate a surface of the river-bed or sea-bed. The reason is that I would like to get the bathymetry for particular reaches of navigable rivers, or lakes.

For instance, I have found that the C-MAP Social Map data includes a reach of the Wilsons River downstream of Seaham Weir. Although I can see it on-screen, and there is an option to output it as a chart to a chart-plotter, I really want the data from which the chart is generated. Also, I don't have a chart-plotter.

NB I use terrain data a lot in my line of work as a hydrologist and civil engineer. The ELVIS Elevation Data Portal curates the publicly available data, such as the high-resolution digital elevation models (DEMs) derived from LiDAR surveys, which I find invaluable. However, these surveys do not extend below the water surface, which means that if I need a river-bed, like the Wilsons River, I need to look elsewhere, or pay for a survey. Hence, the question.


HI Archenar,
I can't think of a free service, but I'd suggest having a chat to Tidetech. IIRC, their whole model for their tidal flow gribs is based on mapping the sea floor and then simulating water movement over it. Really smart stuff. And they're Aussie.
Penny the boss is a gem and Paul Freeman (their sales fella) is a yachtie and a genuinely lovely guy. Maybe they could add some knowledge about free and paid resolutions etc that could help you out?
Cheers!
SB



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"Getting the community soundings data from C-MAP Social Map Data" started by Achernar