I can't handle photons!:

(1) I don't see any reaction on changes in photon shader parameter. Diffuse, specular, transmit, probability etc.
(2) I can't force my photons to go through my object. Only few of them are transmitted and diffused after it (although eta = 1 and I don't want to diffuse them).
(3) Generally speaking I want my photons to go straight on through a surface and hit an object after this keeping surface_color * light_color.


any help appreciated!
thanks,
sy.

In general, you should not need to use photon shaders in Houdini 9 as long as your surface shaders are set up to output a bsdf (the “F” variable - all default shaders have this correctly configured). Depending on your scene, it may ignore the photon shaders altogether and use only the surface, which may have a different scattering property than what you've configured in the photon shader.

If you just want to transmit photons, you should be able to use the default glass shaders shipped with Houdini and render a caustic photon map. Just make sure you also have a diffuse surface in the scene to pick up the photons, and that your light is reasonably close to the scene - see attached example.

Andrew

Is that mean that “photon programming” is not trendy any more? All is done via BSDF model? What if I need to do something “special” - supernatural?

thanks for help!
sy.