and are YOU supporting Greg Zaal on Patreon?!

All HDRIs on HDRI Haven are now technically free to download. And they are good. I testify. So if you like using maps to light your scenes, check out his stuff if you haven’t yet. Greg keeps on adding more regularly. And if you want to feel good about using them, you can chip in on his Patreon with an amount that won’t make a hole in your pocket.


can people be Bryce-incompatible?

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.

The takeaway:
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.

today I learnt…

…that HDR maps exported directly out of the Sky Lab in Bryce 7 as EXR are kinda different.

The torus on the left uses the Cook-Torrance model built into 3Delight’s trace() shadeop. The torus on the right uses the Ashikhmin-Shirley one. Look closer, and you’ll see that the A-S model somehow thinks the skymap is grayscale, while C-T does not.

It’s not the best example, really, but it’s a fact. I’ll post a more noticeable one later.


My old skymaps I rendered to HDR “normally” are seen by both models as coloured.

I need to see if saving to actual Radiance HDR will change anything about the way Sky Lab exports maps (it’s significantly faster than having the whole scene render!!). Failing that – I’ll have to figure out what all those parameters mean and if they affect the export somehow.

I don’t even know the mechanism that may cause this to happen. Damn, I honestly don’t feel like reading through the whole OpenEXR specification.

just in time

DAZ3D just unrolled a Victoria 8. And a new free female Genesis model – which isn’t called Genesis 4 but Genesis 8.

I don’t have the time to look at the free one right now – but the marketing talk includes “a new expression engine” and “automatically flexing muscles”.

For the latter to be included in a base figure – or at least a major character like V8; no idea yet if the free one features it or not – I honestly applaud. One of the reasons the original Genesis is my preferred figure is because it has a system like that available in one of the add-ons (Muscularity, I think). G2F had a similar add-on (which I also have cuz it was in a nice sale), but nothing of the sort is out there for G2M (and I can’t be bothered to convert all those JCMs and MCMs, y’know).

Now, expressions, I wonder if they did hire someone with a basic understanding of anatomy.

No idea when I’m going to look into that, but hey, as soon as I do, I’ll drip some acid right here.

Meanwhile fire up your DIMs and go download the new G8F starter essentials. They say there is some clothing there. It’s reasonable to assume it’s backwards compatible ;D