Animated streamlines are an extension to standard streamlines which are very similar to particle advection. Particle advection is an extension to streamlines where massless particles are animated travelling along the length of the streamlines. Animated streamlines are similar, except that the streamlines themselves are animated, with a small segment of the lines being displayed travelling along the line, from start to finish. As usual, the streamlines and particles or streamline segments may be coloured according to the magnitude of the vector field at that point.
This provides a powerful dynamic aid to streamlines. It resolves the ambiguity of the direction of the particles and also shows the strength of the field with the velocity of the particles.
Further, if the particles or streamline segments are displayed on an appropriately small scale, then whole data volumes may be visualised, although depth aids may be required. Animated streamlines and particle advection provide for observing an entire data cube of moving particles or line segments as they move, which neither hedgehogs nor static streamlines can provide. When combined with the interactivity of being able to move the viewpoint, they are nearly unparalleled in terms of observing how particles in the system would move in the vector field.
However, when visualising an entire data cube care must be taken to not overload the user with information and visual complexity. Depth cueing is a simple shading technique which essentially adds a ``fog'' to the scene, allowing the user to easily see how far away objects are. Since the data content is quite high, and these techniques are based on streamlining, they can be quite computationally expensive, which is a factor to consider when attempting interactivity.