search

melowntech / vts-browser-cpp

VTS Browser C++ library
BSD 2-Clause "Simplified" License
53 stars 19 forks source link

What is the standard unit used for altitude? #12

Closed shrikant-panchal closed 4 years ago

shrikant-panchal commented 4 years ago

As per the geojson standards, the unit of altitude is in meters in geospatial co-ordinates.

We have realtime data of some geolocations including altitude in meters, how can we accurately place it in 3D space?

Does navToPhys(vts-browser-cpp) or convertcoordsNavToPhys(vts-browser-js) expects the altitude in meters or in some other units?

malytomas commented 4 years ago

Navigation SRS is defined in the mapconfig. The referenceFrame->model->navigationSrs is the name of the SRS, which is used as a key into the table in srses. These definitions contain both horizontal and vertical components, including the datum.

The geographic-wgs84, which is most commonly used in navigation srs, uses degrees for horizontal and meters above ellipsoid for vertical component.

shrikant-panchal commented 4 years ago

Thanks Tomos! I was using ASL data instead of AGL. AGL data for altitude gave me acceptable results.