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Re: Checker problem 500 Fizzy Grids in North America

[Resolved] Checker problem 500 Fizzy Grids in North America
February 22, 2021 06:25PM
Can you help or clarify what we're seeing?

Checker on this cache is not accepting a grid square that it should.

Cache is https://www.geocaching.com/geocache/GC94ZY4
Checker is https://project-gc.com/Challenges/GC959T5/58078

Cacher is Forbez. Grid square not being counted is D=4.5 T=4 state=PA, with cache GC47TXM. While the mystery cache virtual location is on the state border with NJ, he tells us that the cache (actual) is in PA.
https://www.geocaching.com/geocache/GC47TXM

He qualifies anyway, but the output shows that he was missing this square... and he's not.

We're confused? Will this be a problem with Mystery caches near state borders? Is it using the virtual location instead of the real final cache location?

Carolyn and Carrie
Mrs.Hoagie and Stews Crew
Re: Checker problem 500 Fizzy Grids in North America
February 22, 2021 07:00PM
You are quoting the wrong checker.
The checker for GC94ZY4 is https://project-gc.com/Challenges/GC94ZY4/57860

But about GC47TXM the listing coordinates are United States / New Jersey / Hunterdon County (NJ)

At Project-GC the listing coordinates are in relation to the polygon map (OSM boundaries) and clearly showing in NJ
Geocaching,com is allowing CO's to determine the location which is not always correct in relation with the boundaries
Re: Checker problem 500 Fizzy Grids in North America
February 22, 2021 07:02PM
This is a mystery cache. The stated coords could be anywhere within 2 miles of the actual cache. However, this CO placed the virtual coords in the River on the PA side of the state line.

And the final location is definitely within PA.

I'm confused how either of these results in a polygon that indicates the cache is in NJ?

Is it possible that the polygon is in error here?

Thanks.

Carolyn
Re: Checker problem 500 Fizzy Grids in North America
February 22, 2021 07:30PM
I only tell you how the PGCs boundary file works. States boundaries are third party census data which we have no control over. If the CO's intention is that the cache is in PA. he should move the listing coordinates into that State and not in the middle of the river.
Re: Checker problem 500 Fizzy Grids in North America
February 22, 2021 08:46PM
So these stats do NOT use the ACTUAL cache location, but instead the virtual placement in cases of Mystery caches.**

Good to know.

And there's no way to control where the polygons place the borders, even if they're wrong. Folks should expect trouble with borders of counties, states, and countries. The "middle of the river" in this case actually IS in Pennsylvania, on the PA side of the river middle, but due to your use of external data, the location is determined to be in another state.

Also good to know.

Sadly, there are almost 21 years of geocaches out there, before people had any way to know any of these things would be different in the future.

Thanks for clarifying.

**One remaining question: does this flaw also apply to Multicaches? That is, are multis also recorded in Project-GC as being at their initial and not final locations?
Re: Checker problem 500 Fizzy Grids in North America
February 22, 2021 10:23PM
For as long as challenge caches exist the challenge criteria has always been the listed data on the cache page.
Re: Checker problem 500 Fizzy Grids in North America
February 22, 2021 10:50PM
You can see the polygons we use if you are a premium member using https://project-gc.com/Tools/MapRegions. They aren't perfect, but for nearly all cases it is sufficient.
Re: Checker problem 500 Fizzy Grids in North America
February 22, 2021 11:15PM
The challenge criteria is listed on the cache page, but the checker doesn't confirm the criteria.

I reviewed the polygons, and I can see that the polygons in this area... well, that's even odder. There are apparently multiple overlapping polygons defining the Delaware River here! I do agree; the Delaware takes an odd path. But having multiple polygons in the same area only muddies the water, so to speak.

Regardless of which polygon you use for the stats, there is a stretch of PA, both river and a strip of park land, that's assigned to New Jersey by the polygons. I can share this with cachers. I don't know if the CO in this case is still caching. If s/he is, I'll share it with her/him as well. I'm not sure how far s/he'll have to move her/his cache to make it comply with either set of polygons.

But my question remains unanswered: It appears that you are saying that the Project-GC stats do NOT use the ACTUAL cache location, but instead the virtual placement on Mystery caches. IS this also true of Multicaches, that is, do stats on multicaches also record only the initial virtual and not the physical location of the cache?

I'm trying to clarify for myself so that I can explain to the folks questioning their stats, without misleading them.

Thanks.
Re: Checker problem 500 Fizzy Grids in North America
February 23, 2021 12:26AM
@Mrs.Hoagie

About the "apparently multiple overlapping polygons defining the Delaware River" it clearly states above the map of the Map Regions that the polygons are not as broken as they may seem at the map. Region-levels do not overlap even if the visual polygons of the Map Region-tool may look like they overlap.

Quote

"The polygons might look a bit broken when you look closely to them, for example you can find gaps or overlapping. This is only in the presentation layer, it's an optimization to save CPU in your web browser. The polygons used to allocate regions for the caches have more vertices and are more exact."

About using the posted coordinates for the stats then yes, Project-GC has always used the posted coordinates for caches with hidden finals for all statistics, checkers, tools and so on. Geocaching.com also uses the posted coordinates for their statistics and searches.
Re: Checker problem 500 Fizzy Grids in North America
February 22, 2021 11:52PM
As the guidelines state
Quote
Challenge cache criteria must come from information broadly available on Geocaching.com and must be verifiable through information on Geocaching.com.
This means that only listed coordinates are broadly available for all cache types.
End coordinates for mysteries, multi's, wherigo's etc. can not be used.
Re: Checker problem 500 Fizzy Grids in North America
March 06, 2021 05:02PM
Thank you! We didn't understand "broadly available." That's good to know.

That doesn't apply to this problem, however, since the "Broadly Available" coords are also in PA.

We do now understand that Project-GC gets it's polygons from some other service, and thanks to the twisty turny nature of the Delaware River in that part of the PA/NJ border, there are several lengths of PA that are assigned to NJ, and several lengths of NJ that are assigned to PA, including but not limited to portions of the PA half of the Delaware River, where the cache in question is located.

So while Project-GC does use the posted coords for this cache, and the posted coords are in PA, the twists and turns of the Delaware River apparently cause the polygons to assign that section of the River along with nearby park land in PA to the state of NJ. (And North / West of here, sections of River and parkland in PA apparently get assigned to NJ.)

Gotta love the crazy state border that is the Delaware River.

Sad, but understandable. Programs are only as good as their data.

Thanks for explaining.

This can be archived. We'll ask any cacher (Forbez) who is not happy with these results to take it up with the folks who provide the polygons to Project-GC.

Carolyn & Carrie
Mrs.Hoagie & Stews Crew
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