Coordinate Systems

Triad Orientation

These options allow you to change the coordinate system used by the transform gizmo or triad. As a default, the triad uses local or “Geometry” coordinates.

Geometry

With Faces, Z is aligned with the face’s normal or perpendicular. With a single edge, an axis is aligned with the edge. With a single vertex, the average of the faces connected to the vertex is used to orient the triad. With two adjacent vertices selected, the triad is oriented to the connecting edge. When the selection no longer has relevance to any of these scenarios, the triad reverts to world coordinates.

Screen Y is vertical on the screen and X is horizontal.

World

Uses the world coordinate system.

Lock Orientation

This button allows you to lock the current orientation of the triad at a given angle. Typically you will select an edge or face in Geometry mode to pick up its orientation and then Lock Orientation and proceed select and modify other objects