Blender addon to setup image based lighting (IBL) nodes in Cycles

setting up image based lighting (IBL) in Cycles isn't all that difficult but creating a versatile setup requires a lot of repetitive actions that lends itself well to automation. In this article I present a simple add-on that may be accessed from the Add menu in the node editor to quickly set up all the nodes for environment lighting.

Note: as of 2015/03/13 a bug fix release is available on GitHub.

The SIBL archive

One of the resources I find myself using quite often is the SIBL archive. Each archive is basically a directory (commonly packed as a .zip file) that contains both a high resolution backplate and HDR environment and reflection maps. It also contains an .ibl file that documents the resources available in the .zip file. The add-on uses this .ibl file to create all necessary nodes and references to the images. I am not sure how widely accepted the SIBL format is, but the add-on can also be used by simply selecting a .jpg and a .hdr file instead of a .ibl file so you are not restricted to just SIBL files.

Installation

Download the add-on

It is available on Github as a single file sibl.py. You can directly save it to your download directory via this link.

Install in Blender

Open the add-ons section of Blenders User Preferences and click Add external add-on. Select the downloaded file and click install. After installation you may find it in the Node section where you can activate it.

Usage

With a SIBL archive

Enable the add-on

In the add-ons section of the user preferences. It sits in the Node category.

Download a SIBL archive

Unzip the archive

Go to the World nodes

Click the world icon in the node editor.

Click Add -> Sibl Environment Setup

Select the .ibl file

Click Add Environment

With separate files

Enable the add-on

In the add-ons section of the user preferences. It sits in the Node category.

Go to the World nodes

Click the world icon in the node //editor.

Click Add -> General Environment Setup

Select one or two files

If you select more than one file, a file with a .hdr extension will be used as the environment lighting and the other one as the backplate.

Click Add Environment

After selecting the files the node setup will be displayed in the node editor. If there were any issues with the .hdr or backplate images the corresponding environment texture node is colored red. This may happen if the file is unreadable for some reason or if the the .ibl file points to non existing files.

Options

When the file selector is opened to allow you to select a file, some options are available in a panel on the left of the list of files:

Use reflection map

This one is only present when opening a .ibl file. It selects a higher resolution environment map suitable for glossy reflections (if available). You probably should only use this if you want to see the environment reflected in glossy surfaces because a reflection .hdr uses a lot more memory than a low resolution .hdr environment map.

Clear node tree

Uncheck this if you want to keep any existing nodes in the world node tree. If unchecked a world output node will be reused if present, as are any texture coordinate and light path nodes. Other nodes are untouched.

Implementation details

While developing this add-on I noticed that the [Environment] section in some .ibl files was spelled without an n. This is probably a bug but this add-on accepts both spellings. (An .ibl file is formatted as an .ini file, a common file format on windows and easily parsable with Python's configparser module.
All meta-data in .ibl files is ignored. This means any sun or additional key lights defined in the file are ignored. Also, all image files are currently assumed to be spherical (a.k.a. equirectangular or LatLong format, Blender's default mapping for environment textures). This means that light probe maps are currently not supported.