Welcome guest, is this your first visit? Click the "Create Account" button now to join.
Page 1 of 2 12 LastLast
Results 1 to 10 of 12
  1. #1
    Master
    Join Date
    Feb 2011
    Location
    Sofia
    Age
    38
    Posts
    736
    Rep Power
    222

    Default A geodetic task with a Garmin handheld

    Not many people know it but could be interesting and useful to many. Think at the end would enter in the How To section. So here the task.

    You are on the shore looking at lets say an Oil Platform:

    800px Cromarty Oil Platform

    and you are wondering how to determine its coordinates? By chance you have a Garmin handheld with you. So how are you going to determine its coordinates? Approximately of course.

    Regards,
    DD

  2.    Advertissements


  3. #2
    Kanopus
    Guest

    Default

    Are you asking if we remember that outdoor GPS can have Sight'N Go function? Or would you like to describe how to perform triangulation with this function?

  4. #3
    Navigation software expert A geodetic task with a Garmin handheld
    A geodetic task with a Garmin handheldA geodetic task with a Garmin handheldA geodetic task with a Garmin handheld
    Giomen's Avatar
    Join Date
    Apr 2009
    Location
    Suomi-Russia
    Age
    56
    Posts
    2,155
    Rep Power
    684

    Default

    Mark point (1) and determine course (1) onto Oil Platform. Go to next point on the shore and go to mind course (3) and distance to it from point (1). Mark point (2) and determine course (2) onto Oil Platform in it. Switch to calculator and resolve triangulation task with known value. Make the projection of Oil Platform point and see coordinate for it. More points would give more precision result...

    Another way determine course onto Oil Platform. Then correlate three value for distance: the height of device, the length extended hand this handheld, the height of something on Oil Platform (people, helicopter, safety boats...) . And again math, math and math...
    Garmin, how much is 30 pieces of silver for Judas today? Were they worthy for crucifix of GPSPower?

  5. #4
    Garmin Expert babj615's Avatar
    Join Date
    Sep 2010
    Location
    USA
    Posts
    105
    Rep Power
    58

    Default

    Something even easier that requires no math or any devices other than the Garmin GPSr:

    Mark a position along the beach and save as waypoint (A).

    Standing at waypoint (A), use Sight 'N Go to project a waypoint in the direction of the oil rig, selecting a distance that is clearly well beyond the oil rig. Save as waypoint (B).

    Move down the beach as far a distance as possible, and save as waypoint (C).

    Standing at waypoint (C), use Sight 'N Go to project a waypoint in the direction of the oil rig, selecting a distance that is clearly well beyond the oil rig. Save as waypoint (D).

    Now, open the Route Manager application and select Create Route. Create a Route starting at waypoint (A), to waypoint (B), to waypoint (C), and finally finish at waypoint (D).

    View the selected route on the Map screen of your Garmin GPSr, and zoom in where the route crosses over itself (near the center).

    Mark a new waypoint (E) at this intersection.

    Waypoint (E) is the approximate location of the oil rig.


    Do I win a prize?
    Last edited by babj615; 25th September 2013 at 02:57 AM.

  6. #5
    Master
    Join Date
    Feb 2011
    Location
    Sofia
    Age
    38
    Posts
    736
    Rep Power
    222

    Default

    He-he-he, very well! Seems I am not the first one who knows how to achieve this simple triangulation task. I understood it before couple of days and thought it is really cool. Strange but no such function in the Garminz. And is really practical. Also the handheld needs to have an electronic compass.

    Do I win a prize?
    Yes, lets say a beer if we see each other some day.

    Ok, so here are images depicting the explanation by babj615. Images are always better than words:

    [Only registered and activated users can see links. ] [Only registered and activated users can see links. ] [Only registered and activated users can see links. ]
    [Only registered and activated users can see links. ]

    Maybe it is even better to be made more than two projection points so to be achived better accuracy of the crossed point.

    In fact Giomen method is also applicable. But we need to take two land points at the same distance from the current position in a straight line. (determine their coordinates) We should also determine the angles to the point we want find its coordinates. Then simple calculation of the isosceles triangle needs to be perform. I will try to write it next time if someone don't do it first.

    Good!
    Last edited by ddabcd277; 25th September 2013 at 12:40 PM.

  7. #6
    Garmin Expert babj615's Avatar
    Join Date
    Sep 2010
    Location
    USA
    Posts
    105
    Rep Power
    58

    Default

    May I add a task?

    I once was searching for a puzzle type geocache with multiple waypoints. To find the solution for the final location, the user must first find three pre-determined waypoints, each of which has a unique distance measurement associated with it. The final location is precisely the given distance from each of the original three waypoints.

    Using only your Garmin GPSr, how would one plot the solution?

  8. #7
    Master
    Join Date
    Feb 2011
    Location
    Sofia
    Age
    38
    Posts
    736
    Rep Power
    222

    Default

    With circles? The distance is the radius of each circle. The solution would be the point where the three circles cross each other. Hmmm...approximate point? Not sure which handhelds have it though...

    [Only registered and activated users can see links. ]

    Do I win a prize?

    P.P.: GPSMAP 60CSX have it.
    Last edited by ddabcd277; 26th September 2013 at 09:51 AM.

  9. #8
    Garmin Expert babj615's Avatar
    Join Date
    Sep 2010
    Location
    USA
    Posts
    105
    Rep Power
    58

    Default

    Quote Originally Posted by ddabcd277 View Post
    With circles? The distance is the radius of each circle. The solution would be the point where the three circles cross each other. Hmmm...approximate point? Not sure which handhelds have it though...

    [Only registered and activated users can see links. ]

    Do I win a prize?

    P.P.: GPSMAP 60CSX have it.
    Hmmm, did you read the complete request?

    Quote Originally Posted by babj615 View Post
    Using only your Garmin GPSr, how would one plot the solution?
    Your screenshot is certainly not from any Garmin GPSr.

    You're process is correct, but how to complete in the field using only your Garmin GPSr?

  10. #9
    Kanopus
    Guest

    Default

    Solution is exactly the same, mark 3 waypoints and add proximity alarms to them. Not all gps support this feature.

  11. #10
    Member solo_voyager's Avatar
    Join Date
    May 2010
    Location
    Hawaii
    Posts
    20
    Rep Power
    51

    Default

    Take a bearing on it from a known location.
    Move a known distance and take another bearing.
    Make it far enough to give substantially different bearings, say a 30° to 45° difference.
    Two angles and one side make it a standard trig calculation to find the distance to it.
    Knowing the coordinates of the locations where the bearings were taken makes it an easy task to convert the distances to a coordinate.
    Formulas and/or methods should be easy to find in a Google search.

 

 

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •