PDA

View Full Version : Image World vs Textured Environment



taleequale
04-11-2009, 01:19 AM
Hi all,

I'd like to use IBL for my scenes.. but, now, I've got a problem.. can someone explain to me what is the difference between "Image World" and "Textured Environment".. and what is better for architecture lighting..

thanks

rsfd
04-11-2009, 07:20 AM
Hello,

it depends on the hdr images you have.
ImageWorld is for "light probe" type hdri ("mirror ball" imagery).
Textured Environment is for "equirectangular" type imagery - that is a 360x360 spherical hdri projected to a 1:2 ratio flat image.
As these hdri are photographed directly with special panoramic heads, they generally show a much better quality then those mirror ball images.
If you have other projection type hdr-images (e.g. cubic, cylindrical 180x360) you will have to either convert them or UV-map them onto a cube or a cylinder geometrie to use them undistorted.

A common workflow with hdr-lighting uses:
1.
a low-res and blurred version of the hdri into Textured Environment (with Width Wrap Amount set to -1.0 - this "flips" the image, as it comes in "mirrored")
2.
a high-res version of the hdri mapped onto the inside of a large sphere containing your whole scene (this gives the spherical reflection map)
3.
a super-high-res version on a second sphere-geometrie is often used for animations, or whenever the background should be rendered with the scene (otherwise the background image and the 3D render will be composed together later).

Splitting image based lighting into indirect lighting (blurred low-res hdri) and reflection (high-res reflection map) results in faster and less noisy renders as if one would plug one high-res hdri into Textured Environment and use it both for lighting and reflections.

You can automate this setup in Layout with Blochi's very convenient SmartIBL (sIBL) (http://www.hdrlabs.com/sibl/loader.html) plugin.
His site HDRLabs (http://www.hdrlabs.com/news/index.php) is a great place to start to inform yourself about any useful information about hdr-imagery.
He offers also an archive (http://www.hdrlabs.com/sibl/archive.html) with free hdr-images (equirectangular/spherical) which completes the sIBL-plugin.

Hope this is just enough information to get you started!

toby
04-11-2009, 09:30 PM
This is a very common mistake, people using ImageWorld with a standard Spherical texture map. Here's what your environment looks like if you do that :

lwanmtr
04-12-2009, 03:19 PM
Something I found nice is that Skytracer2 will allow you to output HDR images and does the proper stretching, etc...I've done many shots using image world with hdr skies output from there.

toby
04-12-2009, 05:11 PM
Good idea, but I just checked - it looks like skybaker makes a 180 light probe instead of 360. How are you getting that to map correctly? Using the advanced camera set to spherical 360 I baked a sky that rendered identical to a skytracer render -

lwanmtr
04-12-2009, 05:17 PM
I get a 360* degree map..though I either have to flip the image in photoshop or set the pitch to 180 in image world..as well as adjust brightness as needed

toby
04-12-2009, 05:40 PM
Here's what I get. What the hell?

lwanmtr
04-12-2009, 05:44 PM
Set skybaker to Lightprobe

toby
04-12-2009, 06:14 PM
That is lightprobe!

lwanmtr
04-12-2009, 06:47 PM
really? strange...Post you settings in skybaker?

toby
04-12-2009, 07:13 PM
no options for changing the mapping
eh, it doesn't matter, there's a bunch of other ways to do it.

lwanmtr
04-12-2009, 07:15 PM
Still odd that it's not producing the correct image..

toby
04-12-2009, 07:27 PM
Re-loaded the plugin, that did it(?) Weird because CFM does the same thing. Not the kind of error you'd expect.

Oh wait I forgot - I also tried turning on aa at the same time. THAT is what fixes it. Turn it off again, you get 180 again. THAT is weird

lwanmtr
04-12-2009, 07:29 PM
huh..I dont have cfm installed, so couldnt say on that. Maybe UB was trying to use the cfm version of the plug?

toby
04-12-2009, 07:32 PM
no, UB can't use .p, only .plugin
the AA thing happens in both as well.

danielkaiser
04-12-2009, 08:38 PM
Use the Advanced Camera with Horizontal FoV set to Cylinder and at 360, this will give you a panoramic image.

toby
04-12-2009, 08:47 PM
Yes, as I mentioned, I used the advanced camera with success. Just curious about this weirdness.