Realistic Grass (+sky)

[Zmey]

I didnt saw any tutorial on how to make really realistic grass, all i found didnt satisfied me. Ive been trying to working since around 4 days on a decent grass material but cannot do it and when im almost there then everything else (contrasts, colors and exposure) are unbalanced which applies especially to the skies because for normal dark shadows i need to but the sky on a level of like 0.2 but the sun on full 1.0 which gives very strange results (i will never use a HDRi, so keep that in mind). So to the point, the grass never seems real enough, especially when i try the tutorials. (btw this are more or less the foliage tutorial settings with slightly changed colors, the material just dont work)

for the attachments, here are some pictures on how i would like the grass and sky to look (note that the grass differs from sun and viewing angle and strenght very much which i would also like to "simulate") plus my hopeless try to create grass with the provided foliage settings..

[maru]

Hi,
Could you define exact differences between what you are getting, and the reference photos?
As far as I understand you would like to have nice fresh grass instead of dull and desaturated? Here is my attempt (render+scene).
The key here is using proper diffuse and translucency colors and values, and reflectivity.
I find interactive rendering and the new pan and zoom option super useful here, as it lets you tweak the material in real time.
Also in your photos I can see that the sky is overcast, not clear, so the sky intensity can be lowered a bit, and the sun size can be increased, as if they were affected by the clouds.
Let me know if this is helpful, or maybe you are looking for something completely different.

PS. Adding some material variation using CoronaMultiMap would probably improve realism a lot!
PS2. The aerial perspective is made using 3ds Max enviro controls, so if you switch to different view, you might end up with a black screen or something strange. You can just disable the fog in enviro settings.

[Zmey]

thanks for the answer but no. dont you see that it looks just plain unrealistic? i thought corona is made for realism but its all fake. i want to make grass that looks golden when the sun is low and shines on it, bright green when the sun shines through at midday and "muddy" when its not in the sun, like in real life. but all i see is one angel one daytime solutions which is weak. And the sky is already at 0.2 and it was so dark that i had to add a brighter color to it just to make it look not dark grey-blueish but white-blueish. Its all a mess, it seems that corona isnt good in a sense of good for anything else beside still images and archviz. i couldnt imagine an animation with corona where the time of day changes, there is no universal solution. even games have universal solutions, there is no need to adjust the exposure (btw its the most stupid thing ive ever heard, in the real world is also no exposure so why in diverse render engines? makes no sense at all) and the grass fits to the time of the day because its made physically right. i guess i just switch to mental ray, i hope its better implemented.

[Jadefox]

@zmey , You are expecting a one button solution, add a green gradient to a grass mesh , add sun and sky and voila
You refuse to use HDRI which by the way would give you a much more realistic reflection and color cast.

The realism comes in the way in which the grass is realistically scattered on a uneven plane. Your attached pictures
makes that abundantly clear. Their is probably 7-8 different grass models there. Once you have to look in place you can
start worrying about the texture and translucency. Take it from me if you cant get it right in an engine like corona , you are
going to have a lot more difficulties getting it right in other engines.

There is plenty examples on the forum where the grass is indistinguishable from the real thing.
And what is always the defining character for me is realistic scattering. Which really is an art on its own.

[Zmey]

yes i do refuse a hdri because im not going for archviz nor still images. with hdri's you cant change the time of the day and it blocks one off. And yes it would be highly possible and easier to just have one basic "exposure" (one button solution) which would be the standart, like i wrote it is in some other render engines and game engines. otherwise its not physically accurate and is just playing around with the settings trying to use special tricks to make something look how it should be but thats not what a renderer should do. dont corona aims for realism? if yes then why it uses camera settings when the real world has no exposure but a constant physical lightning approach. exposure will never be physically correct because its not real and thus you cant have like you said "a one button solution" but with a "standart" you would have it.

[Ondra]

yes i do refuse a hdri because im not going for archviz nor still images. with hdri's you cant change the time of the day and it blocks one off. And yes it would be highly possible and easier to just have one basic "exposure" (one button solution) which would be the standart, like i wrote it is in some other render engines and game engines. otherwise its not physically accurate and is just playing around with the settings trying to use special tricks to make something look how it should be but thats not what a renderer should do. dont corona aims for realism? if yes then why it uses camera settings when the real world has no exposure but a constant physical lightning approach. exposure will never be physically correct because its not real and thus you cant have like you said "a one button solution" but with a "standart" you would have it.

Do you know most cameras have "M" mode?

[Zmey]

i dont own a camera nor do i care about cameras. rendering shouldnt be focused on cameras but on a universal standart, a "norm".

[Ondra]

i dont own a camera nor do i care about cameras. rendering shouldnt be focused on cameras but on a universal standart, a "norm".

Well the universal standard are cameras, but nevermind.

Do you have eyes? Do you ever come from dark place to bright place and notice you eyes take a while to readjust exposure?

[Zmey]

the norm is the basic value without artificialization like the eye exposure which you just mentioned. if i put in the sky and the sun into corona, it looks overbright and needs to be adjusted which means its bad.

[Ondra]

the norm is the basic value without artificialization like the eye exposure which you just mentioned. if i put in the sky and the sun into corona, it looks overbright and needs to be adjusted which means its bad.

[Dionysios.TS]

the norm is the basic value without artificialization like the eye exposure which you just mentioned. if i put in the sky and the sun into corona, it looks overbright and needs to be adjusted which means its bad.

So you're now saying that all the rendering engines on planet earth are faulty.... O.o

All the engines don't simulate at all the eye's behaviour but indeed the camera one so like in the real world, the exposure MUST be adjusted in based of the overall scene's lighting. Don't see any strange issue on this!

[sprayer]

the norm is the basic value without artificialization like the eye exposure which you just mentioned. if i put in the sky and the sun into corona, it looks overbright and needs to be adjusted which means its bad.

lol, do you know what your monitor work in 8bit color model and 3ds max in 32bit and can show only what you choose to show, like photoshop working with raw files like any graphic software, where is no simple solution. And what you want can achieved not only by materials and HDRI you need to model floor, several types of grass, scattering, occluded objects etc. You attached not simple lawn with one size grass

[romullus]

i dont own a camera nor do i care about cameras. rendering shouldnt be focused on cameras but on a universal standart, a "norm".

Please enlighten me on that universal standart, a "norm". I always thought that there is something beyond physics, it looks like you have found it :]

[romullus]

And just to demonstrate that maru's scene works perfectly well, i'm attaching couple renders. I just added some variation to grass colour and reduced translucency from 0,4 to 0,2. As you see it works as it should - it stays green in shade or when sun is behind the camera and lights up in bright yellowish colour when sun is in front. No changes to material are needed to achieve that. The only things that changed between those two shots, are sun azimuth angle, camera exposure and white balance - that is exactly what would happen in real world, no matter if you would you use camera or your own eyes and brain to capture that image. Yes, your eyes has built in exposure control mechanism and your brain has built in WB control, no universal standart is needed, i'm affraid.

[maru]

Now when I read the whole post I think that OP really has a point. We should work on the standard.
We should also remove motion blur and dof, because they do not exist in reality. They are just the side effect of using cameras which have shutter speed and f stop, which are both SO WRONG.
The last step would be removing noise, because what's the point of it anyway?

</irony>