Foam in water..?

Hello,

I was just watching the Anonymous making of and I am trying to recreate the wave/foam setup (@ 9:25) that was shown in the video by Rony

I am wondering how this works, so basically the particles are rendered with broken images of waves as bitmap and fed to particle system, how is the image broken up?

Are the rendered particles again input to the displace 3d on another wave image with displacement?

Also please point me to any tutorial displacement from camera...

Thanks..