Author Topic: Map Source - any neat tools/features  (Read 1593 times)

0 Members and 1 Guest are viewing this topic.

CocaColaCacher

  • Sr. Cacher
  • ****
  • Posts: 326
Map Source - any neat tools/features
« on: December 02, 2010, 20:30:36 »
I've started playing with mapsource but if there are any useful features, please let me know. (or if there is a different/better tool to use).

I'd be interested in drawing circles, lines, angles, projections etc.

EX:
I've got all of the way points for "Centre of the Circle" http://coord.info/GC15619, and "wasted" just enough time to get another cache.  I've calculated the approx location of the cache by playing on GPSVirtualizer but there has to be a better way.   

cron

  • Guest
Re: Map Source - any neat tools/features
« Reply #1 on: December 02, 2010, 20:53:11 »
I've got all of the way points for "Centre of the Circle"

C'mon. Even your 450 will be able to do that (I think). No need for Mapsource.

To find the center of a circle going through three known points, all you need to do is:

1- find the point in the middle of A and B and the bearing from A to B
2- find the point in the middle of B and C and the bearing from B to C
3- project a waypoint from midpoint AB, +/-90 degrees from the A-B bearing (depending on the side you need to project)
4- project a waypoint from midpoint BC, +/-90 degrees from the B-C bearing (depending on the side you need to project)
5- create a direct route between AB, BC and their projections

The center is where the two lines cross.

Otherwise, you can also use sinus and cosine, but it's takes more time.

EDIT: Added a visual representation (made on... Mapsource). But I tell you, all of this can easily and quickly be done on your GPSr in the field.
« Last Edit: December 02, 2010, 21:38:15 by cron »

CocaColaCacher

  • Sr. Cacher
  • ****
  • Posts: 326
Re: Map Source - any neat tools/features
« Reply #2 on: December 02, 2010, 22:37:28 »
Yeah, I'll keep away from the calculus thanks.  I don't mind algebra.

I can't use the 450 yet, have to wait until Christmas, in theory  ::) .

I'll have to practice my field geometry on the GPSr so I don't have to make return trips after doing the calculations at home.

bluelamb03

  • Administrator
  • Big Time Cacher
  • *****
  • Posts: 1633
  • Good hunting everyone!
Re: Map Source - any neat tools/features
« Reply #3 on: December 07, 2010, 00:57:19 »
Your eTrex Legend will do the same routing trick that cron explained above.
I learned about this routing ability doing DOUBLE CROSS by binthair (GC364C) http://coord.info/GC364C.
There was a CCC Workshop that featured this technique earlier this year. You could always ask for another...

Experiment with proximity circles too, available from the waypoint 'more details' button....

Blue -
« Last Edit: December 07, 2010, 00:59:40 by bluelamb03 »
Without shared stories we are strangers.
- Sheila Mendonça