Jump to content
Sign in to follow this  
Followers 0
J Grouchy

...calculate crossing point

Recommended Posts

I can't seem to get find a method in either the GPS Visualizer or Geocaching Toolbox sites. I also can't seem to get it input correctly on the GCC app on my phone.

 

Basically what I have is two sets of N/W coordinates and a bearing direction from each point. Where these two lines intersect is the third point I need to come up with. The bearings are noted as S 33° E from the first point and N 63° E from the second. For GCC, it just needs a straight number value, so I converted the first to 147 and the second to 63. Those values do not work, so I'm obviously messing it up.

 

Anyone care to explain it to this fool? :laughing:

Share this post


Link to post

You could try Ruler, Line in Google Earth, but it's not exact. That is, I don't see a way to put in the exact bearing.

 

Mark your starting point, draw a line as close to the bearing you want as possible, save. Repeat. Zoom in to where the lines cross. If you zoom in too far, the lines start disappearing! Get coordinates.

 

Also, you seem to have calculated the "S" number differently than the "N".

Edited by msrubble

Share this post


Link to post

Also, you seem to have calculated the "S" number differently than the "N".

 

That's where I'm a bit confused and I profess a bit of ignorance.

 

So north = 0°, right?

So S 33° E from the first point, I go 180° = south, therefore, 33° East from there is 180 - 33 = 147°, which is a slight southeastern bearing.

Then, with N 63° E, I just go 63° out from 0°, so 63° from the second set of coordinates, which is a northeastern bearing.

 

But like I said, I'm obviously doing it wrong because GCC says there is no intersection, even though in my mind there should be.

 

I know the CO uses Topo! mapping software for his calcs (he told me in an email), but I do not have access to that. Anyone know of a source for calculating it?

Share this post


Link to post

I can't seem to get find a method in either the GPS Visualizer or Geocaching Toolbox sites. I also can't seem to get it input correctly on the GCC app on my phone.

 

Basically what I have is two sets of N/W coordinates and a bearing direction from each point. Where these two lines intersect is the third point I need to come up with. The bearings are noted as S 33° E from the first point and N 63° E from the second. For GCC, it just needs a straight number value, so I converted the first to 147 and the second to 63. Those values do not work, so I'm obviously messing it up.

 

Anyone care to explain it to this fool? :laughing:

 

It's a triangulation problem. If it's more than a few miles it needs great-circle calculations.

 

The azimuths given are weird. I would look on a map to see what makes sense. But the numbers you came up with seem right to me.

Share this post


Link to post

I can't seem to get find a method in either the GPS Visualizer or Geocaching Toolbox sites. I also can't seem to get it input correctly on the GCC app on my phone.

 

Basically what I have is two sets of N/W coordinates and a bearing direction from each point. Where these two lines intersect is the third point I need to come up with. The bearings are noted as S 33° E from the first point and N 63° E from the second. For GCC, it just needs a straight number value, so I converted the first to 147 and the second to 63. Those values do not work, so I'm obviously messing it up.

 

Anyone care to explain it to this fool? :laughing:

 

It's a triangulation problem. If it's more than a few miles it needs great-circle calculations.

 

The azimuths given are weird. I would look on a map to see what makes sense. But the numbers you came up with seem right to me.

 

The two stages are roughly 700 feet apart and the final is supposed to be somewhere between them.

 

I ended up figuring out how to input the points and angles in AutoCAD and found the intersection point from that. The resulting coordinates on Google Maps ended up pointing to the middle of a parking space at the back edge of a church parking lot that borders the woods...so I don't know how my result compares to that of the CO. His "puzzles" tend to run fairly loose with the answers...and he is big into tree identification (leans heavily on that for several puzzles and hints), which I am just no good at. This puzzle has been taunting me for a long while now and I finally decided to just try to clear it out. I just wish there was a better way of inputting this stuff.

Share this post


Link to post

I have several puzzle caches that use triangulation and my favorite Great Circle Calculator http://williams.best.vwh.net/gccalc.htm

The first one that I published was A. Spring GCWE3D.

It has not been found since October 2010. It was found by 6 people that solved it and has had no DNF's.

I also replaced my "Slope Distance" cache with NEW Slope Distance over 2 years ago. Once you have solved the horizontal distance from the top of Mt. Ray, you can get the coordinates for the cache using Ed Williams Javascript Great Circle Calculator.

I'm hoping someone comes out and get the FTF sometime next year after the snow melts.

Share this post


Link to post

I ended up figuring out how to input the points and angles in AutoCAD and found the intersection point from that. The resulting coordinates on Google Maps ended up pointing to the middle of a parking space at the back edge of a church parking lot that borders the woods...so I don't know how my result compares to that of the CO. His "puzzles" tend to run fairly loose with the answers...and he is big into tree identification (leans heavily on that for several puzzles and hints), which I am just no good at. This puzzle has been taunting me for a long while now and I finally decided to just try to clear it out. I just wish there was a better way of inputting this stuff.

 

The Cache Owner / Puzzle Creator has introduced you to Quadrant Bearings. You can Google it, but your initial intuition about their equivalent azimuths was correct. Look at your property survey lines. They should look familiar now, with just a bit more precision than simple integer degree examples. Makes the conversions a little more interesting. And AutoCAD (perhaps set to Surveyor’s Units) is exactly how I would have determined the crossing point.

Share this post


Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  
Followers 0

×
×
  • Create New...