Return to Project-GC

Welcome to Project-GC Q&A. Ask questions and get answers from other Project-GC users.

If you get a good answer, click the checkbox on the left to select it as the best answer.

Upvote answers or questions that have helped you.

If you don't get clear answers, edit your question to make it clearer.

Bug in chart "Average distance by bearing"

0 votes
199 views
In my profile the chart "average distance by bearing" shows incorrect data. I cache mostly in central europe but I have also found a couple of caches in Florida. This of course results in one big spike in the chart. I have this spike, but it points towards about 288 degrees, so a bit northerly. The thing is now that Florida is way south of central Europe. The caches I found there were about 28 degrees N, while my other caches are typically at N48. So the spike should be somewhere around 240 degrees but definitely below 270 degrees.
asked Sep 9, 2015 in Bug reports by efred77 (220 points)

2 Answers

0 votes
Have you double-checked your home coordinates on your geocaching.com account?
answered Sep 9, 2015 by TerraViators (8,120 points)
Yes. The other data in the chart makes sense, just this one spike is wrong. I have found a couple of caches in France and Croatia, both south (west/east) of my home coordinates in Southern Germany and those smaller spikes are displayed just fine.
+2 votes
 
Best answer
The chart is probably correct. You are a bit mistaken about the what is displayed. It uses the initial bearing of the shortest great circle distance to the other point. 
I assumed your home coordinates are near your hides and I used the towns Stuttgart and Orlando  for simplicity. The bearing of the shortest great circle path between the airports in Stuttgart and Orlando is 290 degrees. See the link below
Try LLX-DXB Los Angeles to Dubai. 33 degree north to 25 degree north but the shortest path is 7 degrees and the aircraft almost fly over the north pole.
Put a string on a glob between to point and you will get the shortest path
The measuring tool in Google earth will do the same and show bearing
 
An example that you cant use relative N latitude do determine direction is
Assume your coordinates is N89 00.000 E000 00.000
And the direction to the point N50 00.000 E180 00.000
is 0 degrees (due north) even if the other point is 49 degrees to the south.
All point on the E180 longitude north of S89 E180 the Antipodal point ( the exact opposite of the earth) will have the bearing 0 degrees.
And south of S89 ( for example S89 00.001 E180 00.000) the bearing will be 180 degrees (due south) 
 
The the antipodal point point the bearing is undefined as all paths will be the same distance. And movement in other directions from the antipodal point will result in all other bearings to those points. This example assume that the earth is a prefect sphere which it is not. The coordinates for the point will be somewhat different but the principal is correct.
 
answered Sep 10, 2015 by Target. (Expert) (104,060 points)
selected Sep 10, 2015 by efred77
Ok, very convincing and helpful answer. Thank you very much!
...