# Does LocusPro geocaching circle tool correctly calculated the radius of the circle?

hjhtckoti shared this problem 6 years ago
Solved

LocusPro geocaching circle tool calculates a different radius than, for example the GCC android program. For example, two circles, one of which is located at coordinates N 62 35.684, E 29 45.181 and having a radius of 343 m, second at coordinates N 62 35.524, E 29 46.726 and having a radius of 1695 m. GCC program find two intersection points, but in LocusPro smaller circle is inside the larger one. Which one calculates the radius of a circle correctly?

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Those circles DO NOT cross. The distance between center points is 1356m.

1356 + + 323 = 1679 < 1695

So GCC is wrong. Cant`t tell if Locus draws correctly. I think, I tried once with good success.

Terveisiä Jojensuuhun!

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My mistakes in topic.

The first point radius was 343 m - not 323 as I written.

In screenshot radius was 343 m. So circles must cross.

Compare to GCC screenshots.

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Well, I could use an "inside" man in Joensuu to solve this cache :)

In your original screenshot the larger radius is too large. I got two circle crossings with Locus:

about two blocks west and two south

and two blocks west and one block north.

From the western point.

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Sorry for spoiling to owner. I edit the previous reply, but can`t edit anymore the topic. Can somebody delete this topic after the good solution?

I tried to add circles to the same distance and radius to another location.

Point 1 was N 63 54.117, E 27 14.179 and point 2 was N 63 53.957, E 27 15.795.

The end result was the same: smaller circle was inside the larger one!

So my question is, Why LocusPro draw bigger circle too big?

Bigger circle also change it own size relative to map and smaller circle after I turn on/off gps and zoom in/out, which is very strange behavior in my opinion.

I bought this LocusPro 27.11 last year from android market.

Current version is 2.0.1.

I draw the circles on my mobile phone (HTC Desire HD) in the following order in LocusPro program (Finnish user interface):

Menu > Toiminnot > Geokätkentätyökalut > Piirrä ympyrä

Then I go back to map and check that the first circle was drawn in properly.

After that I draw the second circle in the same manner.

Android version is 2.3.5.

If I don`t go back to map after first circle e.g. draw second circle immediatly after first, the result is that both circles are in same position!

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Does LocusPro geocaching circle tool correctly calculated the radius of the circle?, but I think it`s more like a bug in LocusPro geocaching circle tool.

This reply was created from a merged topic originally titled

<a class="notranslate" href="https://getsatisfaction.com/locus/topics/locuspro_doesent_calculate_correctly_the_radius_in_geocaching_circle_tool/changes"; rel="nofollow" target="_blank">LocusPro doesen`t calculate correctly the radius in geocaching circle tool.</a>.

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I can confirm issue in drawing circle, thanks for report ...

PS: changing topic to "issue"

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hmm much much better but not perfect

do you know any tool where can I check that compute in GCC is correct?

In android is only ability to draw oval by defined bounding rectangle. Is this enough to draw correct circle just with knowledge of `a` and `b` axis of ellipse? have to check it ...

PS: just for your info, two points on circle are manually added expected intersections

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I have my own tool, it gives the same results (rounded):

62:35.694, 29:44.781

62:35.754, 29:44.810

I guess there is no easy tool to draw the circles correctly on map (other than line-seqments :(

PS Does the geocaching projection tool use great circle calculation (e.g. Vincenty`s formulae)?

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Maybe Free Map Tools for graphical comparison. For intersections I found only Matlab with Mapping toolbox.

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Updated to version 2.1.1.

The circles are drawn at the same point every time now.

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v.2.2.3 and problem still exist.

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v.2.4.3 and now program find two intersection points:

65 35.742, 29 44.799 and 62 35.707, 29 44.783

Diff. to stebu own program and GCC still exist:

65 35.754, 29 44.810 and 62 35.694, 29 44.781

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sorry it took so long!

Finally fixed. I also discovered incorrect computations in "project point" feature so it`s also fixed. And finally, lines are now draw also correctly so they`re curved if they`re long

will be in next 2.5.2 version, so check it then please

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just to let you know how it looks ;)

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Now the accuracy is in Place and a great program even better!

Great Job, thank you Menion!

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perfect, you`re welcome and sorry it took so long ...