Hossam Aldin Alaliwi shows how to calculate a tangent using CHOPs or by using the Sweep Node in Houdini.

FX TD Artist Hossam Aldin Alaliwi offers up a helpful tutorial in Side FX Houdini that shows how to handle or create tangent calculations. The tutorial covers calculating with a few different methods including using a CHOPs network, a Sweep node, and by using a rotate Matrix.

Calculations like this are useful for all kinds of stuff in 3D, especially Houdini. Simon Fiedler once showed how to create volume trails by setting up a custom vector volume, using tangents from a curve to control the shape.

Alaliwi has a lot of other Houdini tutorials including training available on his site. Check that out here.