If yes, then I’m definitely one of them.
See, I managed to crash the Sky Lab numerous times by doing rather innocent things (or so I thought). It’s… frustrating.
Yes, you can get an HDRI out of the Sky Lab in a fraction of time it takes to render a scene to HDRI, either in Bryce or in Vue. But there are so many hidden variables at play that it feels worse than going straight down into a Daggerfall dungeon without a recall spell.
For those less dinosaur-CRPG-oriented, I just grabbed a screenshot in Daggerfall Modelling showing (part of) the structure of a random dungeon. If you’re thinking “the hell is that”, well, you’re right. Exactly that.
So I guess it just wasn’t meant to be, in my case. But anyone else is free to try. It is even possible to get a decent EV range in your HDRI from the get-go by fiddling with the parameters.
I’d stick to Vue from now on, though. Yes it’s way slower (a 4096×2048 map takes around an hour to render on my machine, using just the Global Ambience model). But it’s way easier to generate realistic pretty clouds in Vue, if anything. So that’s definitely a winner.
What I can’t seem to squeeze out of my venerable Vue 9 Esprit is any sort of workable dynamic range. So Partha’s GIMP builds to the rescue… If you save the HDR that Vue spits out as an EXR file, you can open it in any of his GIMP 2.9 versions (I prefer the “colour corrected” one). We only want to increase the brightness of our sun, so we toggle the “quick mask” and paint the selection in the form of a single round brush stroke where the sun is. // you need to select the “quick mask” in the “Channels” tab and use white as your foreground colour // Then we disable the “quick mask”, go back to our layer and mess with the “Exposure” slider. It only goes up to 10, but you can launch it as many times as you need (and you can change the selection via the “quick mask” to get a glow around the sun, for example).
So, according to Picturenaut, in the case of this particular map, we go from a measly 3 in dynamic range up to 19. Check out the difference in how this map lights the scene. And also notice fireflies.
Most really good HDR maps will give you fireflies, unless you use a crazy number of pixel samples. If you’re one of those who like rendering overnight, then fine. I’m not like that.
So I finally introduced specular intensity clamping to my shaders. Here, the torus on the left has no clamping; the torus on the right, the ground and the cone all clamp.
Wowie once reasoned that 16 would be a good enough value that kills most fireflies but keeps most of the dynamic range for rendering to HDR. So this is what I used.
I’d say it doesn’t look half bad for a first attempt.
Obviously you can use the GIMP trick to enhance just about any other HDR map you find too dim, not just the ones you render yourself. And while there are loads of real footage HDR maps out there these days, with Mec4D’s ones featuring very pretty locations and all Greg Zaal’s ones being free now, sometimes you do need a map that no-one else ever made.