The ups and downs of HDRI might as well be a roller coaster. Permit me to share a story.
For the longest time, I thought I couldn’t use the fancy new render engine DAZ rolled out with 4.8: Iray. I longed to play with the photo realistic render engine, but having an AMD video card instead of the NVidia the specs called for, I thought I couldn’t.
Fast forward to just before Christmas 2016 and DAZ 4.9. I made a curious discovery about the list of installed stuff in the install manager: a public beta build of DAZ 4.9. So, I tracked it down among my programs and opened it. Played with it some and got curious about the render settings. What should my curiosity behold, but that NVidia Iray was available to play with!
So, I explored, dabbled and started tracking down tutorials. Fast forward again to about mid March 2017. After multiple not-so-good attempts at making my own HDRIs with Carrara. I still have trouble with the lighting in that one. I was exploring a favorite group for 3D artists on Facebook and stumbled across an image that could be rotated 360 degrees. To go with it, a youtube tutorial video on how the trick was done!
Well, again, I dabbled and played. Made a neat city 360 followed by a scene from Techwarrior #5 and put them on Facebook to a very receptive reaction. I realized I could convert that city 360 to an HDRI and use it as a background for renders. Well, you won’t catch me using 3Delight anymore! Scenes with an HDRI background render very quickly even on my older computer and they look amazing!
HDRIs are wonderful as both light and background, but – and this is the downside – they take a long time to render! Smaller size and resolution just won’t work with these bad boys. The ratio suggested in that tutorial was 2 to 1 with a size of about 4000 by 2000 pixels. Be ready for a long wait unless you’re able to despeckle and sharpen effectively in Photoshop. Here’s what I mean:
Not the greatest picture I’ll admit, but this one’s been at it 14 hours and it’s still pretty grainy.
Personally, I set the render time to 24 hours so it would have plenty of time to render as cleanly as possible. Know how many seconds that is? 86,400 seconds! Now, as I’ve pointed out on Facebook, once this is rendered, it can be used time and again as a background and light source without bogging down the scene I’m trying to render. So, when it comes down to brass tacks, the occasional 24 hour render like this isn’t too horrible, right?
The trick is a simple one, but only available in Iray. Setup a scene with lights but without characters if you want it to be a background HDRI – the one in that picture is a dungeon lit only by fire – and add a camera in the center of it. Go into the camera’s parameters and pick on the lens type. Set it to spherical. Then go into render settings and set the size ratio to 2 to 1 and the pixels to 4000 by 2000. For my 4-year-old laptop, there’s no acceleration from the video card, so I setup the render time at 24 hours or the 86,400 seconds I mentioned before. From there, hit render and walk away for the duration of the render.
It’ll take its time rendering considering the size and and how complicated the scene is, but when it’s done finally, it can be converted to an HDRI and used as a background/light source without being so slow with characters. So, it balances out, wouldn’t you say?