Otherwise usage

Around ten million people worldwide have been to see Yann Arthus-Bertrand’s exhibition of aerial photos called The Earth from the Air. The exhibition features shots taken in over 100 different countries and never fails to make a lasting impression on those who come to see it. Although part of the fascination probably comes from the fact that Bertrand is putting on record things that the public could not otherwise see, this alone cannot explain why people are so deeply affected by the photographs themselves.

Which definition of otherwise?

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