Image Based Lighting Basics
It's fairly quick and easy to get photo-realistic results using image-based lighting.
By using Houdini's built-in tools, or by supplying your own HDR (High-Dynamic Range) image, your renders can inherit a deep, rich color and shadows from real world locations.
The shelf tool "Environment Light" is a straightforward approach to IBL. Simply create the light and specify an image for it to use. This should be a panoramic image with 360 degrees of view. Also, you'll get much better results if you provide an HDR image (as opposed to a regular jpeg).
This is what a parorama in Latitude Longitude layout looks like:
And here is an HDR version
of this image to try in Houdini.
A high res version of this image will be found in an upcoming asset : envLight_HDR_Beach
Intro to the Environment Light
Once an image is chosen, the results can be seen immediately.Below is an image which demonstrates some of the various options for the light.
Another option is to include "Portal Geometry"
This allows you to mask out part of your environment image so as to simulate outside light coming into a room through a window or open door. In the example below, a simple sphere with a few faces removed illustrates the dramatic effect Portal Geometry can have.
Once the portal geometry is specified in the light, and "Use portal" check ON. The original geometry can be be hidden. It will still affect the render untill checked off again.