If so, you'll need a spectrometer with carefully-chosen geometry. If not, anything will do.
Sorry, disagree. When measuring textiles (or any other textured and/or uneven material) the shadows produced by a single-angle illumination are the biggest issue. —— Like so many things there is an element of truth in both positions…
There are a number of fairly smooth inkjet fabrics that can be color managed quite well with either a large aperture 0:45 or 45:0 device or with a device in scanning mode where the “virtual aperture” combined with suitably larger patches solves the same issue. Class is correct though that at some point changing geometry is the best answer – though I’d hardly say the “biggest issue”. Like many non-paper substrates when you move to other substrates each comes with a host of challenges of which measurement geometry is only one of many. RayC