This only works in the 3delight for Maya Plugin and not currently in the 3delight Studio Pro Package. works in both now
3delight has shipped with a sun and sky shader for a while, but there have been issues around them (which I believe the developers are looking into). Now with the support for the MR shaders its easy to get something setup quickly and with the use of scripts to modify the time of day, year, location etc.
Ok first thing make sure that you’ve got Mental Ray plugin loaded
Window –> Settings/Prefrences –> Plug-in Manager, find in the list Mayatomr.mll and check Loaded is Autoload.
go to Window –> Rendering Editors –> Render Settings . Change drop down menu ‘Render Using’ to Mental Ray
From the ‘Indirect Lighting’ tab create a ‘Physical Sun and Sky’
In the Maya Outliner you can now see a ‘Sun Directional light has been created and in the utilities of the hypershade there is a mia exposure, mia physical sky and mia physical sun. There are mel scripts available to change the directional light based on the time, julien day etc. I recommend to download the ‘TOI’ set of tools to do this.
Create a 3delight pass , turn on global illumination in the render setting with add to final mix. Heres some quick and nasty renders.
In addition I would look at modifying the directional light and shadows color temperature based on the time of day. These images don’t feature any aerial perspective shading. The viewer would normally expect to see destauration based on distance – dependent on time of day again.