Projection Question

[+albsch]

I want to obtain projection information for two known points. I know the location of both point A and point B and can calculate the distance between them but how to I obtain the direction and degrees from A to B? I am using a Garmin 60CSx and can project from one point by inputting the degrees and feet but don’t know how to work this backwards. There has to be a simple why to do this. I am finishing up a 6 part multi cache and this will be used to locate the final hide.

[+smithdk]

I want to obtain projection information for two known points. I know the location of both point A and point B and can calculate the distance between them but how to I obtain the direction and degrees from A to B? I am using a Garmin 60CSx and can project from one point by inputting the degrees and feet but don’t know how to work this backwards. There has to be a simple why to do this. I am finishing up a 6 part multi cache and this will be used to locate the final hide.

 

This is how it works on my Vista C so it should be similar on your unit. First make sure both waypoints are loaded to your GPSr. Then goto the waypoint page of one of the points. From there you should be able to select "find near here" and when you select the other point, it will show the distance and degrees.

[Grasscatcher]

I want to obtain projection information for two known points. I know the location of both point A and point B and can calculate the distance between them but how to I obtain the direction and degrees from A to B? I am using a Garmin 60CSx and can project from one point by inputting the degrees and feet but don’t know how to work this backwards. There has to be a simple why to do this. I am finishing up a 6 part multi cache and this will be used to locate the final hide.

 

I don't believe the first reply will work....you would have to be standing at the first point with your GPS and then read where the second one was from there.

 

However, you can easily do what you want in Mapsource.

 

Make a Route of those two points. Select it and choose Route Properties, then the direction Tab, and the directions will tell you the bearing from the first to the second.

[+smithdk]

I want to obtain projection information for two known points. I know the location of both point A and point B and can calculate the distance between them but how to I obtain the direction and degrees from A to B? I am using a Garmin 60CSx and can project from one point by inputting the degrees and feet but don’t know how to work this backwards. There has to be a simple why to do this. I am finishing up a 6 part multi cache and this will be used to locate the final hide.

 

I don't believe the first reply will work....you would have to be standing at the first point with your GPS and then read where the second one was from there.

 

However, you can easily do what you want in Mapsource.

 

Make a Route of those two points. Select it and choose Route Properties, then the direction Tab, and the directions will tell you the bearing from the first to the second.

 

Back in early 2006 when I first started caching, I worked a multicache that required projecting. It required projecting from the very first waypoint for all of the stages. I actually drove back to that waypoint each time to get the next stage. I found out later that this was not needed since you can select that waypoint and project from it (as if you were there). Since then I have did a lot of caches requiring projecting. The Garmin 60CSx does have the "find near here" option so my suggestion should work. I just now tried it with my unit and it worked fine. Your suggestion should work too.

[+smithdk]

I want to obtain projection information for two known points. I know the location of both point A and point B and can calculate the distance between them but how to I obtain the direction and degrees from A to B? I am using a Garmin 60CSx and can project from one point by inputting the degrees and feet but don’t know how to work this backwards. There has to be a simple why to do this. I am finishing up a 6 part multi cache and this will be used to locate the final hide.

 

There is also a handy program that will do it for you:

 

http://www.fizzymagic.net/Geocaching/FizzyCalc/index.html

[+albsch]

Thank you for the help!

 

Al

[+LifeOnEdge!]

I want to obtain projection information for two known points. I know the location of both point A and point B and can calculate the distance between them but how to I obtain the direction and degrees from A to B? I am using a Garmin 60CSx and can project from one point by inputting the degrees and feet but don’t know how to work this backwards. There has to be a simple why to do this. I am finishing up a 6 part multi cache and this will be used to locate the final hide.

 

I don't follow your question. Normally, when someone writes an ambiguous question, several will post with the solution to what they interpret when they read your post. I'm going to take each of your statements/questions, unravel them, and have you nod affirmatively and correct me when I don't get it.

 

I want to obtain projection information for two known points. I know the location of both point A and point B and can calculate the distance between them ...

 

Known points? Know the location? I assume you mean: I know the coordinates to both points A and B. Generally, without the coordinates, you won't know the distance between two points.

 

... how to I obtain the direction and degrees from A to B? ...

 

Totally confused here. Direction AND degrees? Did you mean "... how DO I obtain the direction IN degrees from A to B?"

 

... I am using a Garmin 60CSx and can project from one point by inputting the degrees and feet but don’t know how to work this backwards. ...

 

The Garmin GPSmap 60CSx will project a waypoint from a known waypoint by inputting a distance from the first waypoint and the degrees you wish to project this point. Yes. To get the angle between true north and the angle made by the two waypoints, you first need to determine the distance north/south and the distance east/west between these two "known" points. You got this information when you calculated the distance between the points, right? From there, and assuming the distances are not too great, simple trig will get you the angle. The arctangent of the ratio of these two numbers will give you the answer in relation to True North.

 

Two Points, A and B. Two numbers for each point, n and w. Four points total: An, Aw, Bn, and Bw. Right?

 

Arctangent [(Bn-An)/(Bw-Aw)] <--- expressed in length (not coordinates) and relative to point A. (you don't want the angle in relation to some other point in space, right?)

 

You got the distance between the coordinates based on the northern position and scaled this appropriately, since the closer you are to the north pole, the shorter the distance from one angle of arc to the next arc in the west direction.

 

This angle then needs to then be converted to the standard convention. I did everything else for you. I think you can figure this part out.

 

Check your answer: Plug the distance you calculated between the two points and the angle you just calculated, project the waypoint from A, and see if it agrees with the coordinates known for B.

 

I'm curious. What cache is this you are working on? What is it they expect you to do with this information (and more importantly, where do they expect you to be when you're performing these calculations?)

[+EScout]

I want to obtain projection information for two known points. I know the location of both point A and point B and can calculate the distance between them but how to I obtain the direction and degrees from A to B? I am using a Garmin 60CSx and can project from one point by inputting the degrees and feet but don’t know how to work this backwards. There has to be a simple why to do this. I am finishing up a 6 part multi cache and this will be used to locate the final hide.

 

If you know the coordinates of two points, this is not a projection exercise.

In the field (with any brand GPSr):

Enter both waypoints, save and name. Use your "create a route" function, and use these two points. When you are highlighting the second, it will show you distance and bearing from the first to the second point (set up your true or magnetic reference first.)

On your PC, use FizzyCalc as described in an earlier post.