RPC Photonics Diffuser BSDF

RPC Photonics has high quality BSDF measurement data available for their engineered diffuser products and it turns out that with a little help the data is essentially already prepared for use in FRED.  The steps below describe how to use the attached FRED script to merge the supplied data from RPC Photonics into a text file that can be used directly in a Tabulated scatter model in FRED.

  1. Download and unzip the BSDF data to a folder on your computer.  Use their “Raw data” files.
  2. Copy the FRED script file from this KB post into the unzipped directory.
  3. Open the FRED script file and run it to produce an output text file in the same directory with the name “<SAMPLE>_FRED.txt”, where <SAMPLE> is the name of the RPC Photonics diffuser dataset.
  4. In a FRED document, right mouse click on the Scatterers folder in the object tree and select, “Create a New Scatterer”.
  5. In the new scatterer dialog:
    1. Name the scatter model appropriately.
    2. Change the Type to “Tabulated BSDF”.
    3. Right mouse click in the File box and select, “Replace With Data From a File”, selecting the output file from (3) above.
    4. Toggle the “Varies w/angle” option (assumes all RPC Photonics datasets have more than one measurement angle set).
    5. At the bottom of the dialog, toggle the option that scatters in transmission and disable the option to scatter in reflection.  You do want to halt the incident rays.
    6. Hit OK

Once the scatter model has been created on the object tree you can right mouse click on the node and select any of the “Plot” options to verify the BSDF profile and total integrated scatter values.

Download the FRED script: constructRpcScatterFile.frs