I have a friend who studied fashion design. She had to hire a model to model a pair of pants that she designed. These pants are low rise, so regular underwear could easily stick out over the top. So she told the model ahead of time to wear a thong.

When models are doing a job, such as a photoshoot or a fashion show, do the other people have any idea what underwear they're wearing? For example, if they're posing for a photographer in low rise pants, would he be told that they're wearing a low rise thong underneath? Or if they're wearing a revealing shirt, do they know whether they're wearing a bra?

You mean sometimes it's not important? I thought that maybe it's always important due to the possibility of visible panty lines.