The quality of these will vary greatly, many require a supplemental light source (usually in the location of the sun) to cast ‘hard shadows’…most are non-comm only. Some are in spherical mapping, most are equirectangular/latitudinal-longitudinal mappings…a few are in both, very few are cubic. 3Delight, Luxrender, Cycles and Octane all can use them too. There are links to various HDRIs scattered all over the Iray threads…well, HDRIs aren’t just for Iray.
