The cardinal spline is a cubic Hermite spline whose tangents are defined by the endpoints and a tension parameter. The tangents are calculated with the previous and the next point following the segment:
Ti = 1?2 (1-c) (Pi+1 – Pi-1)
where c is the tension parameter, which is a constant that modifies the length of the tangent. This parameter is not specified separately in COLLADA 1.4 and is instead baked into the tangents that are provided by the OUT_TANGENT and IN_TANGENT inputs to the sampler.