Conventions#

Handling NeRF dataset format#

Hint

Wisp’s acceleration structure follow the conventions of Structured Point Clouds (see OctreeAS), which require coordinates in the range of [-1, 1].

Wisp normalizes data to fit within the range of [-1, 1], which is opposite to the approach that Instant-NGP takes.
The diagram below illustrates the different flows:

Instant NGP Coordinate System

Coordinate Spaces#

Camera Coordinates#

By default, the camera coordinates in wisp are aligned with OpenGL (right handed coordinate system). This convention can be done by calling Camera.change_coordinate_system().

Wisp Camera Coordinate System

NDC Space#

The default NDC space in wisp uses a y-axis up, z points inwards (that is: a left handed SCREEN coordinate system).

Wisp Renderer NDC Space