VRay leaves...

[jacksc02]

Really nice leaves

[peterguthrie]

I love this thread. Seriously. People being passionate about how best to make 3d leaves. Rocks my world

[3DMK]

I love this thread. Seriously. People being passionate about how best to make 3d leaves. Rocks my world

I Agree Peter....some days I thought I was one of very few who was looking at this as something very important. How wrong I was

The biggest issue I think most people are overlooking here is the fact that proper variation of the colour of leaves will do more for creating realistic looking leaves than any amount of technically correct materials.
The ONLY practical way to get good leaf variation is to blend your leaf maps with VERTEX COLOUR variation. I have never seen a tree or plant that has exactly the same colouring on ALL it's leaves. The colouring will always change depending mostly on the age of the leaf.
The only program that has the ultimate control & placement of vertex colours IMHO is GrowFX.
I suggested & tested with the developers of GrowFX over quite a long period to impliment a second-to-none Vertex Colour options & the outcome was even better than I imagined [thanks to the talent & hard work of the programers at GrowFX]

So before everyone gets stuck on having physically correct/perfect materials, I suggest taking some interest in making trees with Vertex Colours..... you will be blown away by the overall improvement in the realism of your leaves.

Cheers
Jamie
PS. I will try to post an example of what I mean when I get some free time.

[windowlicker]

Good point, Jamie. My next plan (when I have the time) is to deal with the variation. Instead of vertex color, I plan to map noise/gradient maps on different map channels so that you will get a variation of color over the whole tree. I've had a similar approach for the tree trunks of my latest trees, and it works quite well. I've tried to achieve a quick way of UVWmapping and texturing trees imported from Onyx. I figure I need a similar workflow for the leaves. I don't want to spend several hours doing anything too advanced.

And thanks, Pixelcon!

[vlado]

It features several models for describing absorption and scattering, but the stochastic approach (section e), and particularly the "SLOP model" (figure 11) looks like it could be made into a shader fairly easily.

I made a sketch as a suggestion to how I figure it would work.

[ATTACH=CONFIG]11805[/ATTACH]

So where do the three textures come into that (front, back, translucency)?

Best regards,
Vlado

[tricky]

That's an interesting question; and would you be willing to pay for them (if they are really quality materials with high-res textures)?

Best regards,
Vlado

Absolutely we would.

[windowlicker]

So where do the three textures come into that (front, back, translucency)?

Well, I figure it would be more or less the same interface as the 2sided material that we already have, except that the actual blending of the materials works a bit differently. The specular aspects of both front and back materials are reflected off the surface, and excluded from the scattering calculation. The diffuse light from back and front surfaces is gathered, and distributed according to the scattering amount - where 0 would be identical to a completely opaque material, and 1 would give an equally bright front and back side.

I'm pondering if it's important to use only the actual lighting for the scattering, and then using that scattered result to light the diffuse map of either side. The other option is to light the diffuse maps of either side, then do the blending. The results would be a bit different. Maybe that could be another parameter - the diffuse color impact on lighting?

The translucency map and the tint map wouldn't need to be separate per se, but it might be practical for some reasons, like when you want to control tint color and tranlucency over several materials globally.

Also, giving the option for a transparency setting would be nice. That way you could easily control the overall transparency without having to edit that in the base materials.

One other thing that would be great, but not necessary, is blurring of the scattered light. In thick leaves you will see blurring since the internal scattering is so great. Not sure how to control it though. Maybe a value in pixels or world units?

Made a quick mockup.




The important issue is that it is only the diffuse component that is scattered, and the specular component is unchanged. Adding the extra features would be incredibly useful for creating naturalistic leaves though.

[3DMK]

I've tried to achieve a quick way of UVWmapping and texturing trees imported from Onyx. I figure I need a similar workflow for the leaves. I don't want to spend several hours doing anything too advanced.

The best thing about using vertex colours is that it's super quick & easy to use [even with onyx] it should take you less than 5 mins to set up vertex colours, not hours & hours
UV mapping is also done in 5 mins with GrowFX & Onyx & X-frog, so there should be no need to do any mapping once your tree is imported into max
Have a quick go of Vertex colour & you will be amazed at how simple it is to use & get awesome results almost instantly!

Hope this helps
Jamie

[Dariusz Makowski (Dadal)]

Absolutely we would.

As long as they are at 5-10k texture res if we talking about shaders...

[Morbid Angel]

Honestly guys I don't quite understand when people complain they can't get a metal shader to look right, and complain about lack of consistency or availability of a certain metal shader that would be the mother of all shaders for that particular metal. Vray is a tool for the artist to use to get results, people shouldn't blame the tool when they cant get something to look good. I am sure that some kind of standardized model for things is a good starting point, but any professional look dev artist would be able to create a metal or whatever shader he needs no matter what the tools he has.

I personally think thank vray our of most of renderers out there has the most friendly shader structure which is really geared towards regular users and allows for a great deal of control. But control means big room for error on user part. Sure vlado can write a metal shader, where he would just have 3 values and everything else would be physically based. But then people will start to complain that they cant put a texture into this and that and we go back to the beginning.

If you doubt that, open maxwell or indigo shader and good luck.

[joconnell]

I'd disagree to an extent Dmitry. I love vray as a renderer and find it incredibly quick and flexible to set up shots. For example I'm working on a film at the minute where I've a vehicle in a desert setup and it's literally set up good shaders in a master file, merge it in to each shot and then load a hdri into a domelight. Align and shot more or less done for comp.

But, in certain cases where I want to push something a tiny bit, or break physical accuracy a tiny bit then the option isn't there. For example being able to multiply an sss effect in the sss2 shader, as in keep the amount / distance of bleed but be able to ramp up the strength of the effect. Or having a self illumination slot in the main material? Fair enough it'll break the accuracy, but at the same time we're faking everything anyway, so it just adds a tiny bit of convenience! Brazil seemed to be the most tweak / hack friendly with the unbiased stuff on the other side. Vray is in the middle with "Ideals" which serve nearly anything we ask for, but there's a few occasions where we just need to break things a tiny little bit and we're done, but that's outside the ethos of the renderer.

[windowlicker]

Well, I think most of the options in vray are perfect. A great combination between artistic possibilities and physical accuracy. Saying it's up to the artist to use whatever tools provided, and that the artists are to blame when they can't create that perfect metal (or plant or whatever) - I think that's a bit of a flawed argument. In many cases the talent and tenacy of the artist IS important, but if you take that argument to the extreme: Try recreating any scene in this thread using only a Max standard material.

I do really think it's up to us users to suggest improvements to Chaos Group, and engage in a dialogue leading to improve the renderer. Then it's up to them to judge whether or not they think it's a good idea to implement new features, and of course how to implement them. I guess it is a balance between keeping it somewhat simple for beginners, and yet advanced enough for high end users. So far, they've done a great job, imo.

[Bart247]

Hey Vlado

Can you explain in more detail the process you used in your leaf tutorial (http://help.chaosgroup.com/vray/imag.../leaf_tutorial) to get the correct diffuse colors?

"so to get the correct diffuse colors, we need to divide by the inverse of the translucency color. However we don't yet know what the translucency is, so I just set up a shading network to allow me to adjust that. I used VRayCompTex textures to invert the translucency value and to divide the back and front colors by it"

How would I do this in Maya?
I couldn't find a CompTex node.
Does this approach still apply and is it necessary when using textures for the diffuse values?

[svetlozar.draganov]

For the Substract operation you may use plusMinusAverage node of Maya in Subtract mode, set the Input3D[0] with values of 1,1,1 and plug the Out Color node of the texture to Input 3D[1].

For the Divide operation use multilyDivide node of Maya in Divide mode and connect both textures in the Input 1 and 2.

[Ihno]

Is the leaf tutorial still up somewhere?
Or could it be re uploaded?