Units and Coordinates in HoloOcean

HoloOcean uses meters for units and a right-handed coordinate system for all locations, distances, and offsets.

Coordinate System

Unreal Engine uses a left handed coordinate system by default, however to keep with general robotics conventions, we use a right handed coordinate system with positive z being up.

So, when you need to specify a location in HoloOcean, the format is as follows

[x, y, z] where:

Positive x is forward
Positive y is left
Positive z is up

Remember that the units for [x, y, z] are in meters (Unreal Engine defaults to centimeters, we’ve changed this to make things a bit easier).

Rotations

Rotations are specified in [roll, pitch, yaw] / [x, y, z] format, in in degrees (usually). This means

Roll: Rotation around the fixed forward (x) axis
Pitch: Rotation around the fixed right (y) axis
Yaw: Rotation around the fixed up (z) axis

In that order.