OK Guys n Gals, this is very interesting, but as this is all very new, I hope I can ask a very simple question or two..

Do I understand this correctly?, This technique is used to light a poser scene to accurately match a background image?

For example if I went to the beach and take a photo of the sea and sand, and then use that background image for posing V4 in her swimsuite, I would also, whilst at the beach take multiple exposures and use these photos to create the IBL?

Sorry for such basic questions.