Hi
How does Phantom know about attitude based on sea level?
Is GPS location or baromet which deside that?
Was putting overlay on one of my videos and notis both attitude from Sea Level and take of point.
Useing Litchi.

Google and Here maps do have a reference to Sea Level in their file format. But the Phantom itself dos not register sea level at all . It only registers altitude based on Home Point being initialised by barometer to zero.

Nigel

solentlife Posted at 2017-3-25 09:31
Google and Here maps do have a reference to Sea Level in their file format. But the Phantom itself dos not register sea level at all . It only registers altitude based on Home Point being initialised by barometer to zero.

Nigel

It looks rather accurate. It's less than 2 m difference in attitude.
My house is at 161 m but the Litchi say 159,7 m.

Just putting it in a rough terms ....

Basically areas are surveyed and SPOT HEIGHTS determined which are specific recorded spots with height above MEAN SEA LEVEL. Often they are a small concrete plaque or block placed. In many countrys it is actually illegal to move, disturb or deface them.
Intermediate data is then derived from Topographical surveys of residential developments, industrial sites, farms etc. Plus of course satelite ground tracking and determination.

For a period I worked on Seismic and Scientific Research vessels and we used a specialised navigation system SYLEDIS. This was based on a series of transponders placed at spot height points and they would transmit a signal that we would receive and triangulate with the others. The accuracy was within 1m because it was short range and the spot height position was a registered highly accurate position.
We had a funny incident when we wanted to place a transponder on a registered spot. Some twit in local council ... a certain Mediterranean island .... had allowed a house to be built on top of the spot !!
So to place the item we :

a) Agreed to rent the roof space of the house and pay all electric bills etc.
b) To get up to the house - a steep hillside - we had to BUY the horse and cart.
c) We had to pay for a Security guy to protect our gear.
d) At end of 'shoot' about 1 month ... we had to give back the horse and cart FREE of charge !!

Needless to say the Island in question was Sicily !!  The house and other were all part of the Local Don's requirements to 'allow' us to site the gear !!

Absolutely true story ... no joke.

Nigel