Using RPCs with a mental ray Daylight System
Technical Support has receive a growing number of questions about lighting recommendations for using RPCs with the mental ray Daylight System. I set out to find some good lighting settings that will address the majority of the problems that users are encountering. The following will take you through the steps that I used to get nice looking results without adversely affecting the coloration of the geometry in my scene.
I began by placing two RPCs into an 3ds Max 2009 scene and placing a mental ray Daylight System. Without changing any settings I receive a rendering that looks like this:
The RPCs are dark and poorly saturated.
To address this I first changed the Physical Scale. Physical scale is located on the Environment and Effects dialog underneath mr Photographic Exposure Control. I changed the Physical scale to Unitless and provided a value of 90,000.
Upon changing the Physical Scale the scene will render like this:
The RPCs are brighter but still poorly saturated.
The latest version of the RPC Plug-in (currently version 3.14.0) offers an option to control the RPC's gamma settings. Use this to make the RPC look more saturated. This feature is found by clicking on the Utilities Panel, selecting More and then choosing RPC Mass Utility. I changed the value from 1.0 to 1.4.
Upon modifying the gamma value for the RPCs they should look something like this:
At this point you will notice that the red, blue and green spheres have not had a change in color at all. However, this will change a bit in the next step. I think that the RPCs will look better if I boost the Exposure Value for the mr Photographic Exposure Control.
This option is located under the mr Photographic Exposure Control settings in the Environment and Effects dialog.
To get my desired results I set the Exposure Control Value to 14 (it was previously 15). This effects both the RPCs and other geometry in the scene, but I believe that it makes the scene look much better. You will notice that the color of the spheres was not greatly effected by this change.
These look much better.
Good luck with your renderings and please contact ArchVision and VisMasters Customer Service if you ever need assistance using RPCs in your scenes.
Note: These RPCs had a self-illumination value of 55%. Different self-illumination values will result in different rendering results.
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