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(from a Japanese user)
Hello everyone, I am trying to make a field with lots of cherry trees on a grassland.
In the below image, the trees were made by xfrog, and the ground is a simple plane with simple texture of grass (roughness100, Nd1.0)
I can see green color on the lower surface of cherry blossom, and that must be because of reflection of green light from the ground.

It's not nice.

Could anyone teach me, a very beginner of MW, how to reduce the reflection from the ground?

Konichiwa =)

It looks like a nice wip Maruyama

If you could help us by showing your tree material setup with a screenshot, then we can direct you step by step.
Or just try to set the tree material reflectance to your sakura-pink color and a high roughness value. I'm assuming that you are using 1 standard BSDF layer type material.

Hi,

try to desaturate grass texture, cherry trees (sakura ?) are very nice.

maybe you should first try and get rid of the over-exposure.
in your camera settings there is a value for the shutter speed.
put in a higher numerical value... for example, if it now says "100", type in "350"... just as an example... this will lower the time that the shutter stays open for light-penetration and bring down the exposure.

after that, definitely don't use roughness100 for your grass. for anything actually.
i guess something around 90 would be something to start with, to see what is visible of your texture.

when you start to see your texture and see that it's to be tweaked a bit: there is an image-processing feature in the material editor, which lets you change the brightness, saturation and contrast of the texture used.

additionally: nd=1 needs also to be changed. generally, opaque materials should have an nd >= 3, just a value of nd=8, for example.

now, here comes the important thing about materials:
go to the "think" ressources of next limit and look for tutorials that discuss material creation, that were made by someone called "mike verta".
you can also find knowledge from him in this forum, if you do a search for his nickname, it's "mverta".
the knowledge and tutorials he provided can be called references, i guess. standard-literature, if you will.

btw, if you do that forum search, you'll find the sentance "don't ever use lambertian (roughness=100)" around two or three times... maybe a little bit more often

on top of that: the manual is a great ressource for knowledge, too

welcome to the forum and have fun

(again from the Japanese)
Thanks a lot for your suggestion.
I am now struggling to cope with this reflecting green color.
Here I put my material settings as below.

below is the material setting for JA18brk(this is the bark of cherry trees)


and, below is the texture used for JA18brk reflectance 0 box.

(I also used bump map for the bark but I think this has nothing to do with this issue.)

and, below is the material setting for JA18flo1(this is one of the two types for cherry blossoms)


and, below is the texture used for JA18flo1 reflectance 0 box.


and, because I am using clipmap not on layer but on transmittance box, below is the texture used for JA18flo1 transmittance box.


and, below is the material setting for JA18flo2(the other type of cherry blossoms (exactly same setting as JA18flo1)


and, below is the texture used for JA18flo2 reflectance 0 box.


and, below is the texture used for JA18flo2 transmittance box.


and, below is the material setting for grass ground.


and finally, below is the texture used for grass gound (reflectance 0 box)


Now, I am rendering one more time, but this time, I...

1 dropped down saturation for grass texture,
2 dropped down roughness for grass land material from 100 to 90,
3 changed the Nd for grass land material from 1.0 to 3.0,
4 thought changing shutter speed, but it is 1/750 and so remained the same
5 thought putting pink color to cherry blossom reflection 0 color, but because I am using texture JA18flo1, I didn't. And instead, I put pink color to reflect 90 (it was originally white).

As to the tutorials produced by "mike verta", I will search them soon.
That's all for now.

This scene require a long time for noise-free rendering and so I decided to sleep with my PC power ON. (it's already midnight in Japan !)

Thanks again, honestly.

I recommend starting here:
http://think.maxwellrender.com/tutorial ... ategory=42

Try this also
1) make the grass darker green (in photoshop or something similar)
2) make the sakura more pink colored.

If it still fails, try to do an "isolated render" of a single tree by itself without the ground and use a skydome (white color), just to see if there are any problems with the UW maps or something else in the scene.

good luck

Koji -

I definitely see a lot of basic problems with your material setup, but you can learn these basics quickly. Definitely check out my material tutorial for a quick understanding of the relationships between Reflectance, nd, and Roughness, especially. With a little study, this should be a great scene, and I'm happy to help you once you've covered some fundamentals!

_Mike

mverta wrote:Koji -

I definitely see a lot of basic problems with your material setup, but you can learn these basics quickly. Definitely check out my material tutorial for a quick understanding of the relationships between Reflectance, nd, and Roughness, especially. With a little study, this should be a great scene, and I'm happy to help you once you've covered some fundamentals!

_Mike

Hello again, I am Koji.
A lot of basic problems...
Well, I feel as if I am the only one student who failed the basic exam and so taking extra-course during summer vacation in an almost empty school, and in front of me, there are a group of teachers watching each movement of my fingers on my desk...

But it's great to have many teachers. Thanks really.

I just now completed understanding one basic tutorial as below:


Yeah, thanks a lot, and I have also read the manual of Ver 2.0.
From now on, I...
1 Instead of putting clipmap on transmittance box, I use that clipmap on layer.
2 I don't use roughness100 because this doesn't exist in the real world. (I set roughness 95 or so)
3 I put the same texture of blossom to ref 90 box as well as to ref 0 box, after making a bit brighter, so as to avoid "washed out" look of blossom.
4 I set Nd for blossom material quite low value ( 1.1 or so but not exactly 1.0), because the texture of grassland should not be reflected on the surface of blossom.
5 I still keep using only one BSDF, because I am not making plastic material.
6 I will also lower the saturation for the grass to reduce vividness of green of the ground and make it a bit darker.
7 I will set the roughness value 90 or so to grass.
8 I keep the shutter speed somewhere around 1/750 (this is quite a short time for light exposure isn't it?)

And, I refrain myself from using thinSSS because I am still a beginner.
(By the way, I am setting ISO 400, instead of 100, to make the scene beautiful)

I will post the result soon.

koji_maruyama wrote: 8 I keep the shutter speed somewhere around 1/750 (this is quite a short time for light exposure isn't it?)

(By the way, I am setting ISO 400, instead of 100, to make the scene beautiful)

1/750 is good for light scene, ISO 400 is definitely NOT good for light scene...

Yeah, I agree with you.
But when I set ISO 100, the blossom looks quite dim...almost grey.
Like one below:


Well, the problem might be much more complex than I'd expected.

Here comes the rendered image after making several improvement.


Well, yes, now I don't see green on the blossom surface.
Probably this is the best I can.

The next task upon me is how to make blossom much brighter, keeping ISO 100 or so.
(The above image is with ISO 400)

Maybe this should be another topic.

Thanks a lot.

For a typical sunlit outdoors scene, I start with F-Stop 16, ISO 100, Shutter 125. Adjust shutter to suit.

Yes, I will render again, soon. Thanks.

I finished rendering with ISO 100 & Shutter Speed 1/125 as below:


I see a bit of "blown out highlights" on the background and sky and think it's because of the value of Burn was too high (0.
And so I did again rendering but this time with ISO 100 & Shutter Speed 1/125 & Burn 0.2 (& Monitor Gamma 2.20), and the result is as below:


Yes, I like this scene!

Thank you very much indeed.