spherical.py 文件源码

def lat_long_to_cube_uv(S, T):
    # Convert to Cartesian.
    x = tf.cos(T) * tf.sin(S)
    y = tf.sin(T)
    z = tf.cos(T) * tf.cos(S)

    argmax = tf.argmax(tf.abs([x, y, z]), axis = 0)
    max = tf.reduce_max(tf.abs([x, y, z]), axis = 0)

    # Check which face the ray lies on.
    front_check = tf.logical_and(
        tf.equal(argmax, 2),
        tf.greater_equal(z, 0.0)
    )
    back_check = tf.logical_and(
        tf.equal(argmax, 2),
        tf.less(z, 0.0)
    )
    left_check = tf.logical_and(
        tf.equal(argmax, 0),
        tf.less(x, 0.0)
    )
    right_check = tf.logical_and(
        tf.equal(argmax, 0),
        tf.greater_equal(x, 0.0)
    )
    up_check = tf.logical_and(
        tf.equal(argmax, 1),
        tf.less(y, 0.0)
    )
    down_check = tf.logical_and(
        tf.equal(argmax, 1),
        tf.greater_equal(y, 0.0)
    )

    # Normalize coordinates.
    x = x / max
    y = y / max
    z = z / max

    # Calculate UV coordinates.
    u = tf.where(front_check, 0.5 + x / 2.0, tf.zeros_like(x))
    u = tf.where(back_check, 1.0 + (0.5 - x / 2.0), u)
    u = tf.where(left_check, 2.0 + (0.5 + z / 2.0), u)
    u = tf.where(right_check, 3.0 + (0.5 - z / 2.0), u)
    u = tf.where(up_check, 4.0 + (0.5 + x / 2.0), u)
    u = tf.where(down_check, 5.0 + (0.5 + x / 2.0), u)
    u = u / 6.0

    v = tf.where(front_check, (1.0 + y) / 2.0, tf.zeros_like(y))
    v = tf.where(back_check, (1.0 + y) / 2.0, v)
    v = tf.where(left_check, (1.0 + y) / 2.0, v)
    v = tf.where(right_check, (1.0 + y) / 2.0, v)
    v = tf.where(up_check, (1.0 + z) / 2.0, v)
    v = tf.where(down_check, (1.0 - z) / 2.0, v)

    return u, v