3D to 2D projections: A Camera

bewegung includes a pin-hole camera for simple 3D to 2D projections. In a nutshell, the a bewegung.Camera object can convert a bewegung.Vector3D object into a bewegung.Vector2D object given a location and direction in 3D space, i.e. the 3D vector is projected into a plane in 2D space. Because the “camera” is actually not a rendering system on its own, it simply adds meta data (bewegung.Vector.meta) to the returned 2D vector: The absolute distance (meta["dist"]) from the “pinhole” in 3D space to the vector in 3D space. This allows to (manually) implement various kinds of depth perception, e.g. backgrounds and foregrounds, in visualizations. The camera is a useful tool if e.g. multiple drawing backends are combined within a single animation and some kind of common 3D visualization is required. A typical combination is datashader for density distributions and cairo for annotations on top, see gallery for examples.

class bewegung.Camera(position=None, direction=None, roll=0.0, planeOffset=None, planeFactor=1.0, planeYFlip=False)

A virtual camera for 3D to 2D projections. 3D vectors are projected onto a 2D plane and returned combined with the absolute distance to the camera in 3D space. Vector arrays can be handled if numpy and numba are present.

Mutable.

Parameters

position (Optional[Vector3D]) – Position in 3D space
direction (Optional[Vector3D]) – Direction of view in 3D space
roll (float) – Roll angle in radians
planeOffset (Optional[Vector2D]) – Center offset of 2D plane
planeFactor (float) – Scaling factor for the 2D plane
planeYFlip (bool) – Allows to invert y-axes of 2D plane, i.e. switch to positive downwards

property direction: bewegung.linalg._single3d.Vector3D

Direction of view in 3D space

Return type: Vector3D

get_point(point3D)

Projects a 3D vector onto a 2D plane. Returns a 2D vector combined with the absolute distance to the camera in 3D space (meta["dist"]).

Parameters: point3D (Vector3D) – point in 3D space
Return type: Vector2D

get_points(points3d)

Projects a 3D vector array onto a 2D plane. Returns a 2D vector array combined with the absolute distances to the camera in 3D space (meta["dist"]).

Parameters: points3d (VectorArray3D) – points in 3D space
Return type: VectorArray2D

property planeFactor: float

Scaling factor for the 2D plane

Return type: float

property planeOffset: bewegung.linalg._single2d.Vector2D

Center offset of 2D plane

Return type: Vector2D

property planeYFlip: bool

Allows to invert y-axes of 2D plane, i.e. switch to positive downwards

Return type: bool

property position: bewegung.linalg._single3d.Vector3D

Position in 3D space

Return type: Vector3D

property roll: float

Roll angle in radians

Return type: float