What does "rectangle light options" directional parameter do?

[pailhead]

What does "rectangle light options" directional parameter do?

[simmsimaging]

It focuses the distribution of light rays from (nearly?) 180 degrees down to 90 degrees to the surface of the light. You can think of it as adjusting a broad diffuse light into more of a spotlight. A killer feature (especially when combined with a texture map) and especially when RT supports it so we can tune it better

b

[Svetlozar Draganov]

Directional parameter changes the angle of light emitted from the plane.
When Directional = 0 - the light is emitted from the place in 180 degree angle - the effect is very smooth light , and very soft shadows.
If Directional is set to 1 - the light is 100% directional-parallel - the shadows are very sharp - and the illumination is very strong.
Everything in between 0 and 1 - is blending between these two effects.

[kosso_olli]

A killer feature if it worked right. I recently submitted a bug to Dmitri that caused massive noise and strange patterns when using this feature.

[vlado]

It mostly works right. In the scene that Dmitry sent, without any of the extra plugins, the material renders perfectly fine. I didn't get a chance to debug with all the plugins installed yet (colorcorrect, bercon maps and vraybump2normal).

[edit] There is nothing wrong with the light in that case; just the probability for a secondary reflection ray to hit the light at a suitable angle is very small. You can remove the noise by turning off the "affect reflections" option for the light.

Best regards,
Vlado

[kosso_olli]

Vlado, thanks for the info. Is there a way to clean up the noise while keeping affect reflection checked for the light?

Regards and thanks

Oliver

[Morbid Angel]

It mostly works right. In the scene that Dmitry sent, without any of the extra plugins, the material renders perfectly fine. I didn't get a chance to debug with all the plugins installed yet (colorcorrect, bercon maps and vraybump2normal).

[edit] There is nothing wrong with the light in that case; just the probability for a secondary reflection ray to hit the light at a suitable angle is very small. You can remove the noise by turning off the "affect reflections" option for the light.

Best regards,
Vlado

I installed all the plugins, but the noise effect was unrelated to them I think. I reproduced it using a single material.

[vlado]

No, it's not the plugins; like I said I could reproduce the issue eventually. Nothing I can do about it for the time being though, it's just part of the whole physically-based rendering concept There are some work-arounds like I suggested above.

Best regards,
Vlado