Working with reflections on X-frog leaves (trees and plants)

[N-drju]

Hi Everyone,

It's been AGES since I last visited the forum... Well, let's just say that I had different life priorities.

I have returned to "Terragening" recently. Apart from rendering I also try to visually enhance some of the resources I have.

Right now, I am trying to perfect the vast collection of X-Frog plants and trees that I have. With this, I aim to achieve the following things which, as I found, are lacking or are completely off in the original files:

1. Introduce translucency to all leaves (original X-Frog leaves are fully opaque, with translucency value set to 0 which is nonsense)
2. Add green-tinted color to said translucency
3. Add more accurate IOR to all leaves
4. Add reflectivity to (most) leaves

I put the last item in bold, because this is what I have the biggest trouble with...

Unfortunately, some of the X-Frog trees are fundamentally flawed when it comes to the leaves in this respect. I'm sure that you noticed that the surface of the leaves is perfectly flat most of the time. This, in turn, produces a totally artificial, flat and universally white reflection. Like on a polished strip or mirror-like surface.

My question then is how you Guys go about this issue (if at all). With limited success, I tried to create a reflection mask out of the color files to alleviate this problem. However, this is an extremely time consuming process.

I will be grateful for any tips. I would like to upgrade and "liven up" my 3D flora before I make any renders.

Thank you. 

[Dune]

You should try to make a bumpmap of the leaves, and displace only slightly. The reflection will get a better shape anyway, more natural. PixPlant, or other apps are good at that. Otherwise just turn greyscale and blur a bit in PS, and check will if it's logical.

Welcome back, btw. it's been a while indeed.

[N-drju]

Hey Ulco. Good to read you again, happy to see you are still around. 

Thanks for a tip on PixPlant. I tried it but while it's successful with some plant species, it ultimately seems to misinterpret others. For example, it generated a decent effect on a bottle tree but missed chestnut altogether (just generated a white, smooth-edged map the shape of the leaf missing the entire structure in the middle).

I think greyscale workflow might be good. Tweaking brightness and contrast through GIMP generates some decent images.

[Dune]

The problem (with a lot of bummapmakers, I think) is that they use the photo's colors to interpret a bumpmap (how else?). But when a vein is lower than the rest, but lighter, it will misinterpret this. So you have to check if it's logical and maybe adjust/paint over.
I think in fact there should not really be a reflection map. A leaf is usually reflective all over, so I always only use a bumpmap to vary in the angle of reflection.
Translucency map the same story. A thick light vein may not be more translucent than a dark one. So check or just use one base color.

Yeah, I'm still around. Hooked forever

[N-drju]

Good. You are one of the pillars of this community and software.

I made some more tests and PixPlant does the calculation fine. I simply uploaded the color picture not where it was supposed to be.

Here is the comparison of the results. They look quite promising. PixPlant and greyscale are comparable, though I think PixPlant bump map has a little more definition due to the additional controls that the program offers. Reflectivity in the example is, of course, exaggerated to make the final effect better visible.

[Dune]

That works pretty nicely indeed. IMO it's important to not have the map too sharp, or you get nasty bump and nasty reflections. And you can make it even more varied by applying a PF (world) to bumpmap input. Small scales of course, but not tiny.
You can check all this in TG with RTP very nicely.