Don Culwell , Executive Vice President of Magnetic Dreams takes a look at how to use the custom properties wizard to create a global ambient occlusion shader that you can then link into multiple materials and drive the ambient occlusion nodes of those materials.

Sharing Rendertree properties between materials in Softimage is not as straight forward as it is in Maya’s Hypershade but this tutorial will demonstrate an easy way artists can build their own custom shader panels to control multiple shaders at once

Don notes that this is a simple and easy thing to do in the Maya Hypershade by linking nodes together, and although it is not as straight forward in Softimage, it is possible, creating a custom panel with added attributes for the Global AO shader.