dosch sells an hi-res hdri pak, but I've got one and they're only approx 6400X3200.  there's another group that sells 10000X5000 and those are the biggest I've seen.  google search hdri - there's a belgian group aversis which sells the latter.   what I would like are 19200X9600, but who ya gonna ask?  one would not need one of those with an empty poser scene with nude girl.  for that, a lo-res jpg multiplied by hsv value 4 is more than enough IMVHO.