Naked Science Forum
General Science => General Science => Topic started by: remotemass on 21/03/2024 09:30:42
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GPS point is Latitude, Longitude and Altidude.
Since latidude and longitude can be seen as two polar coordinates angles both within the interval 0 to 360 and altitude can be seen as an interval between, zero, center of the planet and K?rm?n line, let's say: 100 km, to make it more metric.
For instance Big Ben meridian intersection in the equator (prime Meridian in the equator) at sea level would be: 0%, 0%,(6371000/ {100000+ 6371000})= 98.454643 %.
So, if that point in the equator would be GPS: (0%, 0%, 98.454643 %) what the Big Ben highest point would be?
Note, one of the next cities in the two angles from zero to 360 would be Oslo, because is more up North and East. You get it.
- remotemass
PS - 24 digits would be used for GPS/LLA: (xx.xxxxxxxx %, yy.yyyyyyyy %, zz.zzzzzzzz %).
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Problems
1. Big Ben is not on the meridian.
2. Altitude is distance above mean sea level, not measured from the center of the earth. It's not a lot of use for small heights as "sea level" varies from year to year. "Raw" GPS reports altitude above the local geoid - a model that takes into account the oblateness and slight asymmetry of the planet, to within about +/- 10 ft, and precision GPS provides height related to local reference stations that are re-surveyed from time to time to better than 0.1ft.
These things matter if you are flying over London.
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Because of that Big Ben is a good and iconic example as Longitute wiould be near 360 DEGREES of the complete angle, so 99.98%.
Also, that is why this is better, you can reference any point in the total volumetric area of the planet using 3 values. And in the same citie, some of the digits will be static and for that matter could be supressed if you know what you were talking about. Also, is less confusing. People are ultra used to percentages in their daily lifes.
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And in the same citie, some of the digits will be static and for that matter could be supressed if you know what you were talking about.
You can do that for the whole world by using height above sea level.
The Elizabeth Tower which houses Big Ben is 96 metres tall.
Since it starts pretty close to the Thames, the top is close to 96 metres above sea level.
Big Ben, in the belfry of the tower, is about 66 metres above sea level. It's 2.9 metres from top to bottom.
Also, that is why this is better, you can reference any point in the total volumetric area of the planet using 3 values.
Virtually none of which would be any use.
I have a related, but similar suggestion.
Rather than a percentage of the Earth's radius, we use a unit based on the circumference.
In particular, we could use 1/100,000,000 of the length of the quadrant through Paris.
That would, rather conveniently, be the metre.
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Also, is less confusing.
If we're on the subject of needlessly confusing systems, I'd like to know what bright spark thought it was a good idea to call a longitudinal measurement latitude and a lateral measurement longitude. If you apply the same logic to a tape measure my garden path is a hundred feet wide and three feet long.
And whilst we're on the subject of minutes & seconds, I think it's a crying shame that luddites defeated the decimal clock, too.
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Because of that Big Ben is a good and iconic example as Longitute wiould be near 360 DEGREES of the complete angle, so 99.98%.
Clockwise or anticlockwise?
In particular, we could use 1/100,000,000 of the length of the quadrant through Paris.
That would, rather conveniently, be the metre.
or you could use 1 minute of latitude, which is 1 nautical mile, which is why we use it for navigation.
As BC isn't a Londoner, I can forgive Since it starts pretty close to the Thames, the top is close to 96 metres above sea level.
Cos it bleedin' ain't, guv. Yer Thames is tidal, innit, wiv a range of 21 feet at Westminster. If sea level was constant, we'd 'ave no whelks nor eels for sale dahn the cruiser.
Fortunately the conventional GPS coordinate of 51.50050, -0.12463 will find Big Ben on any map, and you can enter it into your autopilot, autohelm, or car GPS with no need for further translation.
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Depends on which way you view the planet. If you are viewing the western hemisphere and its clockwise, the eastern will be anti clockwise, this could create some confusion.
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@BC
Thanks for providing a clear cut differentiation between Elizabeth tower & Big Ben.
Locals should ideally extend this Vital information to International tourists.
Perhaps tourists themselves are to blame.
It's all about clicking ' Selfies ' nowadays.
So little interest n disregard in the rich local culture & history.
ps - say cheez!
: )
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f we're on the subject of needlessly confusing systems, I'd like to know what bright spark thought it was a good idea to call a longitudinal measurement latitude and a lateral measurement longitude. If you apply the same logic to a tape measure my garden path is a hundred feet wide and three feet long.
(a) because they aren't measurements but position vectors. Latitude circles run "sideways" and longitudes run "up and down", which is moderately logical although the Ordnance Survey more reasonably calls vectors "northing" and "easting", in parallel with GPS.
(b) it all depends on how you look at your garden path. An airport runway could be 2 km long x 30 m wide, but the parking apron, viewed from the terminal building, is 50 m long (how far Economy passengers have to walk away from the building to reach the back of the plane) x 500 m wide (so you can park lots of planes next to each other, with First Class close to the terminal)
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An airport runway could be 2 km long x 30 m wide,
Or the other way round in a well known, but politically unacceptable, joke