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<p>Hi Mats,</p>
<p>I will try to answer your questions - although they are a bit
broad:<br>
</p>
1. shortest distance (in the plane) between a point (surfer) and a
line geometry (the coast) - packages like geos or jts can do this
using their DistanceOp function. However, you would need to convert
the GPS coordinate from WGS84 into a local coordinate system (such
as UTM) to do this; assuming that your coast line is already in such
a system.<br>
<br>
2. this depends on your speed of movement and how abrupt you have
changes in direction, which are important for you. To me 10secs
sounds good. I have been looking at bus fleet data with 30sec/point
and that isn't good enough from some applications. So, actually your
application will define what resolution is best.<br>
<br>
3. Probably using Leaflet (<a class="moz-txt-link-abbreviated" href="http://www.leafletjs.com">www.leafletjs.com</a>) and displaying the GPS
points from the surfer. Leaflet has quite a bit of tutorials.
However this requires to have a webserver somewhere. You could
probably also use a map service, such as Mapbox.com or Carto.com to
display your data. But then you need to figure out how to get your
live data into the platform.<br>
<br>
so far my take,<br>
Stefan <br>
<br>
<div class="moz-cite-prefix">On 4/29/17 19:10, Mats Blakstad wrote:<br>
</div>
<blockquote
cite="mid:CAP=1PAVGMO_FadiPRbxABOGpB81-yY=Mm9UGPdRZGEuxu2SYMQ@mail.gmail.com"
type="cite">
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<div>
<div>Hi<br>
<br>
</div>
I work on a student project in a course about Use Design at
University of Oslo. Our project is to help windsurfers; We try
make a small gadget that that they can bring (using Arduino)
that will help them (1) be alerted when they move too far from
land, (2) be able to send a SOS signal indicating their
position if they need help, (3) give them updated weather
forecasts.<br>
<br>
None of us are very experienced with GeoCoding so hope someone
here can give use some small hints or point us in best
correction;<br>
</div>
<ol>
<li>What seem like the most reliable way to measure a persons
distance from land using a gps-coordinate?<br>
</li>
<li>How often should we save gps-coordinates to track a
windsuring trail with good enough resolution but still keep
a minimum file size of gps coordinates for trail?</li>
<li>What is the most simple way that we can create an online
map with trail from GPS-coordinates that we can update live?</li>
</ol>
<p>Thanks in advance for any help and feedbacks!<span
class="gmail-HOEnZb"><font color="#888888"><br>
</font></span></p>
<div class="gmail-yj6qo gmail-ajU">
<div id="gmail-:13u" class="gmail-ajR" tabindex="0"><img
moz-do-not-send="true" class="gmail-ajT"
src="https://ssl.gstatic.com/ui/v1/icons/mail/images/cleardot.gif">Best
regards<br>
</div>
<div id="gmail-:13u" class="gmail-ajR" tabindex="0">Mats<br>
</div>
</div>
</div>
<br>
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