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+1 vote
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Not sure if this is a bug or not. But what happened to the elevation for this cache? It was my lowest by far, deeper than -100 meters. But now it's not even mentioned anymore in my Profile Stats / Finds / Highest and lowest elevations?
in Support and help by NLBokkie (3.2k points)
edited by NLBokkie
same "problem" to other caches in this area: e.g: GC4WXVP and GC986Z3
The same thing goes for #PT Âncora29 https://coord.info/GC6MNVP
I flew 10 hours each way earlier this month, to get there.
Maybe there has been an update to the elevation of the maps Project-GC is using?
Also the problem for GC3T13G and GC986Z3
@chk472 this is not Project-GC's fault. The open-cast mine is filled up with dump. The new data are in accordance with official federal data.
I have the same problem with caches nearby (ex.GChttps://www.geocaching.com/geocache/GC5WVV7).
A view day ago, it was my deepest cache with -67m, now it's elevation is +70m.
In this area i don't think is filled up with dump, it is renatured at the time i logged last Year.
Is their another explanation ?
@SaarFlo99 Your example actually sits on a former mining site, and is a renatured dump, too. The old elevation data are at least 10 maybe even 15-20 years old from what I have seen in the data and opendata history.
So with the use of current and precise data, the elevation match the current (or at least max 5 year old) data.
This region will be surveyed again in 2022, so by the end of that year, the most current data will be available.
Pour old Germany, 15-20 year old data ?
Okay, digitalisation 4.0 is coming in 50 years ;-)
@clappy: Thank you for your Answer.
@SaarFlo99: I would not blame officials this time. The government map data is pretty good and fairly accurate (max. 5 years).
But: Not all data are open to the public (for free) and hence all the free eleveation maps may still rely on old data.
And to be fair: usually elevations do not change very much. Open cast mines or quarries are covering just a tiny area compared to the whole country...

1 Answer

+2 votes
 
Best answer

Project-GC update its data to improve the data, not to mess with people's statistics, obviously. Now I can understand the frustration, not the least when traveling fairly far for a specific geocache to fulfill something special. However, we prioritize correct data, as much as we can.

When it comes to elevation data it's quite unreliable overall. Over the years there are coming more and more technology to resolve the issues, better services becomes available and the data improves. Sometimes it's however that 80% of the data improves, and 20% gets worse. One can of course discuss what level of improvement should be required to change numbers though.

But in this case, as I understand it, it's an improvement of data, showing more current data, which should match the reality better. It's an active mine site, where masses are moved from one place into another over time. If I understand it correctly, there has been a big hole where GC3T13G is plotted, but nowadays there isn't. The old data showing -200 meters seems to be obsolete.

Here is a screenshot showing elevation data of the area as our latest service sees it. It seems to match this Lidar data as well.

If the cache owner wants to keep the -200 meters the cache icon needs to be moved further south east. That requires that the final isn't too far away, and of course that the mystery solution doesn't depend on the original location.

by magma1447 (Admin) (234k points)
selected by NLBokkie
I would like to further point out that offical data from the German federal state of NRW are in accordance with Project-GC's most current elevation data.
This is regarding all the mystery caches around the German open-cast mines Hambach, Garzweiler and Inden.

So rather than Project-GC "stealing" any low elevations, the mines actually move, old parts where coal is retrieved any longer are filled up with the dump, eventually closing the previous hole.

GC3T13G head coords lie at UTM 32U 324441.00 5644612.00 (N 50° 55.584' E 006° 30.112')
Opengeodata from NRW read a height of 104.5 m for this place.
These data were measured in 2016 and will be updated next in 2022.

I am also affected by this change. But to be honest, it was just a matter of time.
@magma1447

Thanks for the detailed info. Then that's the way it is: I learned my lessons and will pay less attention to these statistics in the future. In the end it's just a game...
Thanks for the explanation! Just compared Satellite-Image on GC with geocaching-map :-)
Map has still he -200 elevation and satellite-image shows deepest elevation about 4km south-east of original location.
Let's wait and see ...
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