Vector Fields Over Multiple Trials

I am currently trying to plot a vector field that combines multiple trials. I have 100+ trials of movement data. I have the x and y values, along with the sampling frequency. From that I have found been able to plot the data using quiver:

quiver(x,y,vel1,vel2)

where, x and y are the positions and vel1 and vel2 are the velocities, respectively.

I can do this for each trial and it helps me get an idea of what is going on, however it just shows me on a case-by-case basis and I want to make an overall graph that describes the movement. The ideal graph would be in 3-dimensions (but would happy with a 2-D for now), where x and y is the possible position volume min and max, and the z position would dip down into the graph where the movement was "attracted" (I am basically in need a phase portrait of the system).

If arrows can show "attractors" and "repellors" in this 3-dimensional graph, then I would be one happy camper.

Thank you very much for your help. Feel free to ask any follow-up questions.

-Joel