mia_material for realistic leaves

#61

after reading all this thread again, it’s still very hard to obtain leaves like prodan’s renders.
to resume things most of us are using those 2 things

1-you need a realistic tree model with sky sensitive leaves (from Onyx or Paintfx or other good software).

2-a mia_material with those settings:
diffuse weight:1
reflectibity: 1
glosiness 0.2/0.5
thin walled
fresnel reflection
ao color bleed
transparency 0.25 (compensated in the translucency color by multiply node *4)
transparency glosiness 1
translucency weight 1

again even with those values, we are still very far from realistic leaves/trees.

#62

I believe your mia_material_x settings are a bit off. Why would a leaf’s reflectivity be 1? And not all leaves have the same transparency; setting that to .25 seems to have no physical basis in reality. Play with the numbers to make your leaves proper. Also, a leaf wouldn’t have Fresnel falloff; that’s more for glass/liquids.

#63

yes the reflec value is 1 but i have a reflection color map close to graythat drives the overall value so there is no 100 part reflective part on the leaf. plus u need some glosinnes.
i agree that leafs shouldnt have a fresnel falloff i am using these values here :0.001/1/1.5

now i want to make things clear for the sss textures and sss values (wich are driven by the transparency value): here is some comparisons:

full resolution
http://sor.typepad.com/files/sss_transp_values_comp.jpg

*i dont know if you guys noticed but when the directional sun (direct light) is turned off, sss effect becomes very weak on the leaves (specially the back).But in Prodan’s 4th render:
http://marlas.cgsociety.org/gallery/ it seems that even with no direct ligh, the sss effect is pretty strong,
notice the branch hanging in the middle of the foreground, it’s in the shade but the sss is pretty noticeable. I really wonder how this has been done.

*by sss texture i am refering to the translucensy texture.

#64

Those look great, Royterr. Curious why you’re not happy with your various results? I can see some of those leaves looking great in certain scenes, and some of them looking great in other scenes…

Anything else you were trying to achieve?

#65

the results are pretty promessing so far but not photorealistic.
i will stop when you coudnt tell if its a photo or Mr4Maya render.

now i made these tests so we could all agree on mia_material values.
we all agree on most of the values (diff bump reflec ao) regardless of the top/botoom tetxures.
it seems that the transparency value in most cases is 0.25 to 0.3 max.
the translucency must have a 4 multiplier in the direct light and more than this in the shade.

#66

I think what you got is fine you just need to push it more in post. I played around with it a little in nuke and imo it looks a bit more real. Ima write more tomorrow I super tired and need sleep.
my version is on the left

#67

No offense, Royterr, but no two people will agree on photorealism generally if they know it’s CG. I think your tree renders are great, but without a scene or background involved they’re always gonna look CG. Quality-wise, they’re perfect.

As for settings we can all agree on, that also will never happen! And most plants are VERY different. One species’ settings will differ from another, sometimes vastly. Unless you plan on taking photometric measurements of light transmittal through every kind of plant available, at ever phase of their life-cycle, you’re stretching too hard here. Just find settings that work for the scenes you need 'em for! I don’t believe there are any universal settings, and I don’t even use SSS for most of my work. I like some of yours better, but not enough to say (for example) that all plants need SSS to be “photorealistic”.

Your trees look great my friend!

#68

Infernal Darkness pretty much said what I was going to say. Your work is always going to look “cg” when against a flat background and no scene. You have all the surface properties in your leaves everything looks right I just think you need to create more realistic setup other then the bush agsinst a blue wall. The renders you see from prodan’s work I’m pretty sure had to some extent post work: color correct,grades,chromatic abberation,bloom,etc.

#69

i perfectly agree with both of you on these points.
i know that generaly depth of field/motion blur/chromatic aberration/film grain tend to give the image that last 10 percent of reality.
But i like having a strong photorealistic base before going to post (even in front of a gray background). I usually proceed from the ground up so each element must be 99 percent photorealistic (in my eyes) before proceeding.
Anyway i am going to try to push the shader just a bit further before moving on with the rest.

*Michael i like your CA effect, did you move the rgb channels or is it a filter?

#70

For the aberration I used this gizmo. I agree with you about trying to get the raw render to look as real as possible, I am this way too but what I have begun doing (on personal projects) is when my shaders are close to done I take renders into nuke and do some post work to see how they look. I my self can be very anal and picky about getting my shaders correct and as real as possible but as I began to learn more about compositing/color corrections you tend to save yourself time when it comes 3d vs 2d tweaks. I think your leaves are just as good as those renders from prodan, you have all the correct surface qualites of a leaf. But in my opinion what makes his more realistic is just the shear amount of leaves he has and and as I said before his color grades/corrects,post,etc.

#71

Jeff Patton recently did a nice tut on Translucency, his trick is to use the translucency lume shader.
So if maya has that you should be able to do the same.

http://jeffpatton.net/openb/index.php/2010/05/26/translucent-leaves-in-mental-ray

#72

I don’t think Maya has it, but when I installed mental ray standalone 2011, I noticed the dll file in the install directory. so i guess you can use that

#73

Hi there,

I was reading your post regarding gamma correction as you have 2.2 gamma value in mia_exposure_simple.

But for leaf color or translucency files cant we just increase the color gain value higher than 1. I tried both, Using the gamma correction node and the color gain value… for 2.2 gamma correct value… a value of around 1.7 color gain gave me very similar effect…

So I am wondering what I am doing is fine or am I missing something ? Kindly advise :slight_smile:

cheers,
ak

#74

just use a gamma of 2.2 ans use a gamma correct node of 0.45.

#75

i’m statisfied with my leaves so far, from now on it’s all about finding a descent tree geometry (wich is really hard to find) to achieve a convincing organic image.I hope maya 2012 will include nice paint effects preset trees.

I am running short on time, i will pass to the grass shader now, i am satisfied with the short grass shader below, i will soon focus on medium,high grass (paint effects).

#76

Very nice renders, royterr. Very nice.

#77

thanks alot man.Glad u liked it!

#78

It’s wonderful to see your progress, Royterr! Your plant work is top-notch now, a bit jealous here… Still struggling for photorealism on some projects.

What I’m running in to now is implementation. Perhaps this question belongs in the other thread, though… How to go about making a library of all our plants?

As for biological accuracy, so far Onyx is the best I’ve found. Arbarro is close. But it’s a really limited selection, and I’d love to help work on something more powerful/effective if anyone else is interested.

#79

thanks alot man!

i totaly agree with you on Onyx trees (the renders are onyx trees).
but the convincing trees in the whole onyx library are just a fiew.
as for the grass implementation, its all about how you lay down your patches: big patches layed out manually or small patches painted over a big surface (paintfx paint/geometry paint/custom paint) i dont like the last one because it causes alot of grass geometry interpenetration.

#80

Your leaves do indeed look fantastic, royterr. Very nice job.
For the grass I found the same thing, that painting patches on the surface tends to cause too much interpenetration. A solution with the paint script is to use circular grass patches, and set the offset value appropriately.