What are the coordinate systems in Cesium

[Brian Breitsch]

As a newcomer to the Cesium visualization ecosystem, I find that I am confused when it comes to coordinate systems.

I see Cartesian used to describe x, y, z coordinates, but I don't see anywhere that says whether they are Earth-centered Earth-fixed (ECEF) or Earth-centered inertial (ECI), or none of these. (If I had to guess, they're ECEF.)

With geodetic coordinates, does Cesium convert these to ECEF coordinates?

Would this not imply that there are coordinate conversion utilities in the Cesium library? I cannot find these.

Note: I'm trying to visualize satellite trajectories. 

[Brian Breitsch]

Also, given this information, where would be the best place to document it for other newcomers?

[Brian Breitsch]

Hey I found it!

This information is located in the CZML documentation (https://github.com/AnalyticalGraphicsInc/cesium/wiki/CZML-Content), not the Cesium documentation.
Although--there still should be a goedetic/cartographic to Cartesian conversion routine somewhere in Cesium, correct?

[Kevin Ring]

Hi Brian,

You want Ellipsoid.cartographicToCartesian and cartesianToCartographic.

Cartesian3 can be used to represent any 3D vector, so it can represent inertial coordinates, or an offset from a local reference frame, or any number of other things.  But if the Cartesian3 represents a position, and it's not clear from the context that the position means something else, you can generally assume it is ECEF.

Kevin

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