+Revelatta2B Posted July 31, 2017 Share Posted July 31, 2017 Bonjour, I went up a cache called "Mont Pelat", in the Southern Alps, France. Its code is : GC4M164 This mountain is given in the cache description and by all geographical references (IGN, Google Earth, whatever...) as reaching 3051m However, in the statistics it appears only with 2978m. Any idea why such a difference and a way to have it corrected ? Thanks, Quote Link to comment
+cerberus1 Posted July 31, 2017 Share Posted July 31, 2017 (edited) Didn't see altitude in our stats, so looked at yours. On your third-party stats page, it does show it as 2978m. - Wouldn't that be an issue asked at project-gc? Looking at project-gc's FAQ, under "How is the elevation data calculated?" there's a lengthy explanation... Edited to add, they further explain, " The elevation data does not come from Geocaching.com since it doesn't have that data. We have therefore build our own SRTM-service for the purpose". Edited July 31, 2017 by cerberus1 addit 3 Quote Link to comment
RuideAlmeida Posted July 31, 2017 Share Posted July 31, 2017 Please let's try to keep on topic and be helpful. Quote Link to comment
+famerlor_dragon Posted July 31, 2017 Share Posted July 31, 2017 To cut a long story short: They average heights. So if you are in a valley you may be higher in the statistics, if you are on the summit, you will be lower unless it is a huge plateau. Resolution varies per country. You cannot work around that unless you provide project-gc with better elevation data. HTH! Quote Link to comment
+cerberus1 Posted August 1, 2017 Share Posted August 1, 2017 3 hours ago, RuideAlmeida said: Please let's try to keep on topic and be helpful. As my post was the only one when this was posted, what in my post wasn't helpful? I even supplied a link from a third-party site to help. Quote Link to comment
Keystone Posted August 1, 2017 Share Posted August 1, 2017 (edited) 3 hours ago, cerberus1 said: As my post was the only one when this was posted, what in my post wasn't helpful? I even supplied a link from a third-party site to help. Your post was indeed helpful, so I gave it a reputation point. Another post, which was hidden from view, wasn't helpful. Edit to add: I was not the moderator who hid the post. Edited August 1, 2017 by Keystone clarification Quote Link to comment
+cerberus1 Posted August 1, 2017 Share Posted August 1, 2017 Thanks - and sorry... Quote Link to comment
+Michaelcycle Posted August 1, 2017 Share Posted August 1, 2017 1 hour ago, cerberus1 said: Thanks - and sorry... When I read this thread earlier I had the same thought. Your post was helpful and I could not figure out what the moderator was getting at with that response. The best I could figure was that Captain Clorox had been by but there was no way to tell. I don't think you need to apologize. I apologize to the OP for this brief diversion but I think it would be a good idea that if a moderator is going to post a note like that (and I certainly have no objection in that regard) a short disclaimer to the effect that a post was removed will keep us all from wondering what was wrong with a post that seemed fine. 2 Quote Link to comment
+barefootjeff Posted August 1, 2017 Share Posted August 1, 2017 The elevation data available from most on-line sources is very averaged and smoothed. For example, here's an on-line topographic map of a local headland, showing a gentle sloping hill down to the sea, an old-fashioned paper topographic map of the same place and the actual headland. Quote Link to comment
+fizzymagic Posted August 1, 2017 Share Posted August 1, 2017 Google gives the elevation of the cache as 2994.8 m. I use a complicated method that checks several sources; in the US, in many areas, the lat/lon resolution is 3 m, but for most of Europe the horizontal resolution is more like 25 m. Also, this cache does not appear to be exactly at the top of the mountain, which would make its elevation less than that of the peak. Still, 55 m is a big difference! Quote Link to comment
+duncanhoyle Posted August 1, 2017 Share Posted August 1, 2017 If you want peculiar differences in height have a look at the Shetland Islands in Scotland. As an example,http://coord.info/GC6MYZQ has shows a height of 4389m. The heighest point in the UK is only 1345m! Nowhere on the Shetland islands is 450m so I don't know how averaging errors could be at play The heighest cache in the UK is on top of Ben Nevis but if you look on ProjectGC you'll see that there are 79 caches in the UK which are higher, all of them on Shetland I think. Quote Link to comment
+Gill & Tony Posted August 1, 2017 Share Posted August 1, 2017 Another problem is that the evevation is for the land, not necessarily the cache. My highest cache is on the Jungfraujoch in Switzerland. The cache is at the top of a tall building 120m above ground level. My son has a cache at -5m which is on a pier over water 5m deep. Cache altitude is probably +3m Quote Link to comment
+fizzymagic Posted August 1, 2017 Share Posted August 1, 2017 I went to check out this particular point using the various online web services I know. Here is what I got: SRTM3: 3007 m ASTER: 2987 m Google: 2994.75 m USGS: failed The Space Shuttle radar ranging result is the closest, but it's still over 40 meters off. Quote Link to comment
+The Jester Posted August 2, 2017 Share Posted August 2, 2017 That's one of the nice things I like about GSAK and it's stat macro - you can override the online elevation with the actual. I did that for Death Valley. Quote Link to comment
+Revelatta2B Posted August 2, 2017 Author Share Posted August 2, 2017 Bonjour, Thank you for all these replies, They are helpful. Now I understand better the issue. I am just amazed that there are so many measurements and specially with such differences. And to answer to Fizzy magic, the box is right at the top, which is table like, about 40 sqm. Anyway, thanks again for all the answers. Quote Link to comment
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