Fur + lighting issue

[bbergem]

Hello,

I am trying to use fur for grass and while i find it looks great if the sun lighting is relatively behind the camera, as the camera rotates around to face the sun things get unnaturally dark.. as if the whole area was in the shadow of a building. In the attached test where the sun is perpendicular to the camera its like there is a gradient from looking correct on the left, to incorrect (dark) on the right. Which makes me think there is some kind of calculation at play relative to the angle of the underlying surface rather than the geometry of the fur - as one would expect if the lighting is based on the geometry of the fur itself that the random angles of fur blades would be catching the light still.. not in its own shadow.

I suppose making the grass material translucent or two-sided with translucency could get somewhere but it seems to be a good way of killing render times. The fur is currnetly just picking up the underlying surface which is just a basic grass texture with a bit of soft reflections.

Is this just inherent to the way the fur functions or is there a simple switch/fix that I am not aware of.

[bbergem]

.. perhaps it is just the case that i am just seeing individuals grasses own shadow, and its dark just like the back of the sphere, just looks unnatural and I can't seem to figure out a sensible way to improve it. Any thoughts?

[bbergem]

trying to understand more on a micro level what might be happening, in the attachments to focus on the one brighter blade (red arrow) it shows some highlight, but as i rotate ever so slightly around (blue arrow) the highlight fades out even though i didn't rotate completely away from that highlight so i should still expect to see some.. its like it "fades out." On the very top of the rounded tip you would expect to still see some highlight off that rounded surface, but it gets quite flat. Towards the bottom of that blade a bit of the highlight re-emerges (aka has not complete faded out yet, but if i rotated a touch further it would)

Feeling a bit like the dad in "honey I shrink the kids"... inspecting grass with a microscope!

[bbergem]

ahh ok.. it seems if I make a hair material I get much much better results (had never used it before) which apparently treats the hair as flat planes. Apologies that this thread became my internal troubleshoot record but perhaps becomes useful to someone else. But of course any other advice is surely welcome!

[Zahari.Ivanov]

Hello bbergem

I was able to produce a result which is very consistent with what you've shown us.
The use of hair material seems to be a viable workaround as you have discovered. Nevertheless, we will investigate this further and if we have any updates, we'll make sure to share them with you.

Thank you for your time and for sharing this information with us!

Best Regards!