Hi Mats,
I will try to answer your questions - although they are a bit broad:
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.
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.
3. Probably using Leaflet (www.leafletjs.com) 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.
so far my take,
Stefan
On 4/29/17 19:10, Mats Blakstad wrote:
Hi
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.
None of us are very experienced with GeoCoding so hope someone here
can give use some small hints or point us in best correction;
1. What seem like the most reliable way to measure a persons distance
from land using a gps-coordinate?
2. 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?
3. What is the most simple way that we can create an online map with
trail from GPS-coordinates that we can update live?
Thanks in advance for any help and feedbacks!
Best regards
Mats
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