Terminology

Continuous Image Space

Continuous Image Space is the set of real-valued points in [0,W)x[0,H) where W and H are the width and height of the image in pixels.

Entity Path

The path of an entity is obtained by concatenating the names of all its parents, starting from the scene (whose name is always scene) and traversing the hierarchy until the entity itself is reached. Entity names are separated by / characters.

For instance, a sub-assembly wheel inside an assembly truck will have the following path: scene/truck/wheel.

Normalized Device Coordinates (NDC)

Normalized Device Coordinates are device-independent and resolution-independent coordinates to address points on an image or any other 2D display device. In NDC, points on an image belong to [0,1)^2 where [0,0] is at the top-left corner of the image.