[Insight-users] time step in itkLevelSetFunction

[Amadeus W. M.]

Can someone explain why the time step is computed the way it is in
the function ComputeGlobalTimeStep in itkLevelSetFunction.txx?
I mean the mathematical justification. What are m_WaveDT and m_DT? 
In Level Set Methods, Sethian only mentions (page 67, section 6.4.1) 

max F \Delta T <= \Delta x

A pointer to the appropriate theory would suffice. 

Thank you!