I'm sure that this has been covered elsewhere, but if so I'm struggling to find out where.

Does Google Maps account for the Earth's curvature when calculating distances?

I'm aware that they moved the mapping from the Mercator projection in 2016 to the current 'globe' model, so I'm guessing that it now does.

My tacho wasn't working last summer for a longer term, so sadly I don't know how far I travelled on the ground vs. what Google says!

Cheers,

Ed

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Where Next Barney? Buenos Aires to Lima 2015 | London to Sydney 2015/6 | Armenia, Georgia & the FYR 2022 | Algerian Sahara 2023.

Hi Ed,
I am a map/mapping enthusiast so I clicked your post. What do you feel could be the problem with the calculations? Why would they be inaccurate? Could you explain this better? Are you concerned about elevation changes affecting the X and Y distances?
J

Hello

With and without globemode. (50m gap due to my manual clicking)

When I plan a route on google maps, I have to add up to 1.5 times more km overoll , on a trip.
If it's just 1000km freeway, google maps is good,but still more km needed for gas and food detours.

sushi

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My RTW:
http://www.youtube.com/user/MrXt660ztenere

Thanks Sushi - and I do something similar, though actually go to 2 x the suggested distance for the same reason, with the 'non-motorway' option ticked.

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Where Next Barney? Buenos Aires to Lima 2015 | London to Sydney 2015/6 | Armenia, Georgia & the FYR 2022 | Algerian Sahara 2023.

By 'curvature of the Earth' do you mean projection?

I'm no programmer but I would guess that since Google maps has to stitch in swaths of satellite imagery onto its earth model, it would have to use a geode (I assume WGS84) and that point-to-point distances would be caluclated using the geode, not using the projection of the user-selected area of interest.

You could check this (if the software allows) by measuring a distance between two points and seeing if it changes when you zoom right out and Google Maps flicks from 2D projection to 3D model.

If you are worried that Google Maps measure the straight line distance between two points in 3D space, i.e. it would connect London and Auckland by burrowing straight through the centre of the Earth, this would be very easy to check (and I am sure it does not).

The problem is one of projection, mapping a section of the oblate spheroid we live on onto a flat screen/map.

One a paper map, the common Mercator projection greatly exaggerates area in high latitudes because it 'straightens' the curvature of the Earth.

EO

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EurasiaOverland a memoir of one quarter of a million kilometres by road through all of the Former USSR, Western and Southern Asia.

Surely I’m missing the point here…..?

Seems to me no one is really that interested in direct, point-to-point distance on the earth’s surface except airline pilots. Look at the illustration given above: there are few roads in the Yukon and NW Territories, so what use is a straight line from one place to another, with or without latitude-induced errors of any sort? What you want is the driving distance, which is a whole different thing.

I don’t calculate distances using Google maps, so please pardon my ignorance in advance. As stated above, checking the distance from Auckland (say) to London will confirm that distances in any mapping application are given on the surface, not taking a direct line through the center of the earth. And if you want to know how long a road journey is, just Google up “Driving distance from X to Y,” and you’ll have your answer.

What you won’t get is the driving distance from somewhere in the Fairweather Range (no roads there, although a couple of major rivers and some notable glaciers) and Hudson’s Bay (no roads there either, but one intermittently-operational railway line if you’re interested).

[/cluelessness about what’s being asked here]

Hi J

Great, thanks.

Simple concern is that a distance measured on Google Maps would be longer in real life due to the Maps modelling not taking into account the Earth's curvature.

Ed


Sent from my iPhone using Tapatalk

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Where Next Barney? Buenos Aires to Lima 2015 | London to Sydney 2015/6 | Armenia, Georgia & the FYR 2022 | Algerian Sahara 2023.

In my experience short distances tend to be quite accurate on Google Maps. For very long distances it should be reasonably accurate as long as you follow the exact routing Google Maps gives you. Unfortunately in real life for expedition length trips that simply isn't realistic. Google Maps has led me to abandoned dirt roads cut off by a 10 metre deep ravine and led me to sketchy dirt tracks since those would have been shorter than the maintained roads leading around it. Google Maps often doesn't know the condition of the roads it leads you to or whether they're even remotely usable. It just seems to care about what the shortest distance is.

During the forest fires in the Yukon Google Maps gave me a detour around the closed highway between Dawson City and Whitehorse. It involved using a road which for all intents and purposes no longer exists. The point being that the roads you're actually taking on a long trip are very unlikely to be 100% the ones suggested by Google Maps in most cases.

For a case in point try Port Renfrew, BC to Bamfield, BC. It shows a route of 136Km via the aforementioned ravine or the actually usable road as an alternative at 163Km. On a 60,000 km trip you will likely have dozens of these situations to compound the discrepancies of Google Maps.