Hi Steffen

Yes correct. Modifying the dll is not straight forward.

For the BSDF, you would need an external program like excel or Matlab to create the distribution.

Then for the BSDF format, have a look at those articles:

• BSDF Data Interchange file format specification


• How to use tabular BSDF data to define the surface scattering distribution

It is probably something we need to investigate as these kind of characteristics are common. 

Sandrine

Hi Steffen

The Gaussian_XY scatter function desribes the distribution about the projected specular ray. The scattering does not occur along global X and Y axes.

This can be seen by looking at the documentation provided in the source code, as well as by reading the following article: How to create a user defined scattering function – Knowledgebase (zemax.com)

So when you send a collimated source without any tilts vs the scattering surface, you will find the expected distribution. But when you add a tilt, the scattering pattern will rotate with the angle of incidence.

So I can see two options: modify the current dll or create a BSDF file with your measurement. Let us know if we can help any further and do not hesitate if you have any other questions.

Sandrine