Re: Google Earth: Elevation of water?

Sam Wormley <swormley1@xxxxxxxxx> wrote:

>Terry Pinnell wrote:
>> Sam Wormley <swormley1@xxxxxxxxx> wrote:
>>
>>
>>>Terry Pinnell wrote:
>>>
>>>>As I move the hand pointer across a lake, the displayed data for
>>>>'Elevation' plainly varies, so I assume it must be the altitude above
>>>>sea level of the ground at that point? It plainly cannot be the
>>>>surface!
>>>
>>> See: http://edu-observatory.org/gps/height.html
>>>
>>>
>>>>For example, I'm looking at Ardingly Lake ('ardingly, sussex, uk').
>>>>Other mapping programs I use such as Memory Map etc, tell me its
>>>>altitude is 174 ft, yet GE shows wide variations throughout.
>>>>
>>>>Yet, inconsistently, the English Channel is correctly shown as 0 ft
>>>>throughout, as is the Atlantic Ocean (give or take a foot or two).
>>>>
>>>>Anyone know what's going on here please?
>>>>
>>
>>
>> Thanks, but you're both technically way over my head! What are
>> SRTM3ArcSec files? And that page from Sam is full of techno-babble and
>> acronyms that leave me cold. Is an answer possible in the same simple
>> terms in which I couched the question please?
>>
>
> GPS receivers report attitude above mean sea level. And there is
> error. Typically vertical error is twice horizontal error just
> from geometric considerations.
>
> Maps do too, but are often more quantized.

Thanks for the follow up. But that doesn't explain the distinction I
made between my lake and sea examples. Sea = 0; 0cean = 0-3 ft;
local lake = wide (50 ft) variation.

--
Terry, West Sussex, UK
.

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