Part of the functionality of shaders, is the ability to have full control of the look of your scene within Previzion.
Browsing for Files
With browsing, you are able to change texture destinations manually, without having the back-and-forth of exporting files from Maya to bring into Previzion. This can be useful when switching between day and night in the same setting.
It functions as simply as opening the shader parameters in the Scene tab and choosing Browse next to the channel you would like to change.