9.2.7. Creating point series

We learned in the previous section that a series of N points is expressed as:

[
    [x(t0), y(t0), z(t0), 1.0],
    [x(t1), y(t1), z(t1), 1.0],
    [x(t2), y(t2), z(t2), 1.0],
    [ ... ,  ... ,  ... , ...],
]

The function ktk.geometry.create_point_series can create such series from different forms:

9.2.7.1. Using multiple arrays

In this case, the arguments x, y, and z accept arrays of floats:

import kineticstoolkit.lab as ktk

ktk.geometry.create_point_series(
    x=[0.0, 0.1, 0.2, 0.3, 0.4, 0.5], z=[5.0, 5.0, 5.0, 5.1, 5.1, 5.1]
)

array([[0. , 0. , 5. , 1. ],
       [0.1, 0. , 5. , 1. ],
       [0.2, 0. , 5. , 1. ],
       [0.3, 0. , 5.1, 1. ],
       [0.4, 0. , 5.1, 1. ],
       [0.5, 0. , 5.1, 1. ]])

9.2.7.2. Using a single array

The default argument accepts an array of NxM where M could be 1 (x), 2 (x, y), 3 (x, y, z) or 4 (x, y, z, 1):

ktk.geometry.create_point_series(
    [
        [0.0, 0.0, 5.0],
        [0.1, 0.0, 5.0],
        [0.2, 0.0, 5.0],
        [0.3, 0.0, 5.1],
        [0.4, 0.0, 5.1],
        [0.5, 0.0, 5.1],
    ]
)

array([[0. , 0. , 5. , 1. ],
       [0.1, 0. , 5. , 1. ],
       [0.2, 0. , 5. , 1. ],
       [0.3, 0. , 5.1, 1. ],
       [0.4, 0. , 5.1, 1. ],
       [0.5, 0. , 5.1, 1. ]])

9.2.7.3. Series of constant values

The function ktk.geometry.create_point_series has a convenient argument length for series of constant values. For instance, if we need to repeat a constant point over five samples:

ktk.geometry.create_point_series([[1.0, 2.0, 3.0]], length=5)

array([[1., 2., 3., 1.],
       [1., 2., 3., 1.],
       [1., 2., 3., 1.],
       [1., 2., 3., 1.],
       [1., 2., 3., 1.]])