DomeLight Texture resolution is only taken into account for the importance sampling, i.e. glossy Refractions/Reflection and other blurry effect like DOF, MB and etc.
More information about the importance sampling could be found here: https://docs.chaosgroup.com/display/…rtanceSampling
For all non-blurry rays like Camera Rays, non-glossy Reflections and Refractions V-Ray will always use the full resolution of the image.
Like Svetlozar explained, the resolution is only used for sampling. The default value works fine for most cases regardless of the actual resolution of the bitmap. You will still see the original bitmap where it matters.
‘You will still see the original bitmap where it matters.’ Great, cheers - I was wondering this, as in testing, the reflection looks the same regardless of the Texture Resolution setting.
Out of interest if I set the Texture Resolution as 2048 would the importance sampling for glossy Refractions etc. be something like 45.25 samples (so 45.25x54.25)?