I have a question regarding the BSDF up-vector that I hope somebody might be able to help with -
My previous understanding was that the BSDF “up-vector” should be any vector that is not perfectly perpindicular to the window surface regardsless of the BSDF.
It also seems to be the conclussion from this post:
However reviewing the updated description for HB+
" An optional vector that sets the hemisphere that the BSDF material faces. For materials that are symmetrical about the HBSrf plane (like non-angled venitian blinds), this can be any vector that is not perfectly normal to the HBSrf. For asymmetrical materials like angled veneitan blinds, this variable should be coordinated with the direction the HBSrfs are facing. The default is set to (0.01, 0.01, 1.00), which should hopefully not be perpendicular to any typical HBSrf."
a question come to mind:
- For asymmetrical materials how excatly should the up-vector be “coordinated” with the direction of the HBsrf?
Thank you in advance