Viewport Scale Bar

Displays a cartographic scale bar as a 2D overlay in the Blender 3D viewport. The idea for this scale comes from maps. In the orthographic view, it is intended to provide a quick estimate of the size of an object or structure without using the measurement tool or annotations. That is why the screenshot shows a bridge in side view to give an impression of how large the structure is. In perspective view, the scale bar is not displayed because there cannot be a uniform scale across the viewport.