[OSM-talk-ie] Water depth in lake

Daniel Cussen dan at post.com
Fri May 29 14:10:51 UTC 2015


http://www.openseamap.org/
is a marine map,  which may have depth, or could use depth data.

There may be some legal ramifications in some countries where the
government/department has a monopoly on producing marine charts (which
are maps with depth and other data) as free/open maps may have errors
& the government wants one source. Note sure if that applies for
Ireland:

Anyway this has lready been done!
http://hackaday.com/2015/05/25/project-sea-rendering-autonomously-renders-sea-bottoms/

but yes, if you could marry depth with location data, however there
are some things to take account:
1) Accuracy of GPS, are you recording the current error on position
from the GPS too?
2) Accuracy of ultrasonic (is it affected by temperature etc) tolerence/?
3) Depth is normally displayed on maps as mean tide level (I think),
are you taking into account tide (off shore) or recent rain for rivers
to calculate the actual depth below mean level?

I assume the Garmin is a boat Garmin so takes special boat maps. I am
quite used to NMEA data strings. It may leave out important data such
as accuracy of the GPS at each point in time, depending on which
string you use.

To save time could you not just use a laptop as a datalogger, or do
you want a leave it and forget option? Do you have power limitations
or size or what. Regarding depth are you actually mapping the area or
only places you happen to pass?

Are you doing something else on the boat and was to log the data as a
side project?

I have seen many fishing boats with a full desktop LCD monitor and
trackball mouse, with detailed marine charts instead of small
displays. They can overlay previous routes and they even share
previous areas of fishing between boats.

On 29/05/2015, John Whitmore <captain.deadly at gmail.com> wrote:
> Hello talk-ie at openstreetmap.org
>
> I'm working on a project for work which involves faffing about on a lake
> here
> in Ireland in a boat. What I'm doing is working on pulling NMEA Data off the
> boat's CAN Bus into a computer.
>
> The boat has a few sesnors on it, depth, GPS and will have water Temp, if
> not
> more. There is a Garmin Display which has a maps on it for navigation. I'm
> putting a RaspberyPi with a screen on the boat for something else but I was
> just thinking that I could actually stick a map on the RaspberryPi as well
> and
> use that instead of the garmin. Get rid of one screen. I've used Navit in a
> previous project years ago which I think used OpenStreetMaps, but I might be
> wrong.
>
> This could only replace the Garmin if the maps had depth data for the
> lake. Even if the OpenStreetMap doesn't have lake water depth maybe I could
> write a script to collect that data for the OSM Project? I had a look at the
> OSM maps online and there don't seem to be any water depth data so is data
> collection of interest?
>
> John
>
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