Rendering grass in 3D Max

[Brian Cassil]

Okay folks, this is something I have been struggling with for approximately EVER right now. I'm sick and tired of just about everything in my scene except the grass having a convicing and compelling look to it (architecture, background, trees and shrubs, people, cars, skies, etc. all look great) The grass always comes out looking like painted asphalt or concrete. I've tried everything from a material standpoint, even painting directly from photographs to a bitmap, which actually works really good for arial views, but as soon as I get near the ground surface I hate it. I've tried actually modeling the grass but its just too much for my already huge scenes. I'm wondering if there is any utility that renders realstic grass in the same way that shag/fur/hair renders hair. I know that I could just use that plugin to render grass but $500 dollars seems a little extreme for just the one effect that I'm going after. I'm also told that it takes eons to render a field of grass with shag/fur/hair. Any help would be greatly appreciated.

[Wolf]

I know what you mean,

flat mapped grass looks terrible if not done right,

most grass textures you see around, have been taken from the top, that looks wrong when rendering from eye level.

i find that as long as you dont move the camera too much, a photo of grass taken at eye level, and mapped on from roughly the cameras view, works really well...

 

Shag hair is great

although rendering times that were 5 mins go to 10-15 mins :/

heres a pic with shag hair i did...........

artistnation.com/members/paris/artizen/images/grass.jpg

another way... blur has a script on their site

i think its called simple scatter,

and you just scatter geometry blades of grass everwhere.

again..long render times, but its better than the scatter tools standard in max, cause blurs script uses instances,

so only what your scanliner is touching is in memory at that time.

I have done fields of grass this way.

 

hope it helps

Wolf

 

[ May 08, 2002, 02:18 PM: Message edited by: Jeff Mottle ]

[Guest ghraben]

wolf - are there any options to reduce the amount of geometry in the viewport vs. renderer with the scatter method?

[Wolf]

not with blurs plugin unfortunately,

but i tend to xref anything that is too large with geometry in my viewport

since the grass file will be mostly instances, file size will be tiny, and then i turn off the visible in viewport option in the xref dialog box.

 

honestly guys..for those that havnt looked into xref yet, you all should, its one of the most valuable tools and under rated in max

especially if working on a large project and in teams its just awesome.

[nisus]

Hi lads,

 

I've been looking to make real grass for some time, and recently (about half a year ago) I came up with a trick to make somewhere between 12000-60000 sprites with about 300-600 faces only.

Using very few faces and no shadow casting using grass is not something to worry about anymore (unless you use grass even in the background instead of texture maps ofcourse).

 

here's my trick:

I used a circulair scatter of small rectangles, aligned to the z-axis, and added a noise-masked opacity (treshold: high: 0.6 low: 0.55) stretched to the z-axis.

That way I got a rectangle with small stripes.

Now scatter the rectangle and basicly you're done.

 

You can further make cylindrical objects consisting of about 300 rectangles each add drap and drop them in your scene.

 

Make sure your grass lot is filled with lots of rectangles and that it looks like a volume covering your grass area.

 

To change the amount of sprites simply change the noise treshold values.

 

Your grass will look like mowed grass and when viewed from eye-level will look very realistic because all the sprites are visible.

 

To make it even more realistic you can drop a few meshes of longer halms very close to the camera. This will make the whole a bit more irregular.

 

I hope this trick helps you out

 

If you want to see some images: Check them out at:

http://www.ams.be/eng/projecten.html

ARKiTECH (the project at the top)

 

(Unfortenately, the site is still using frames, so I can't directly link to the images)

 

rgds

[Erik Lund]

Yet another way for quick and good looking grass would be to create a grid plane (patch or mesh) over the area that you want the grass. The more grid squares the better looking the result will be. Then go the the edge level of your mesh and select all the visable edges, Shift-Drag the edges up 2-4 inches. Now create a sub object material with 2 slots. The first slot should have a grass texture image taken from above. The second slot will contain another texture of your grass. This second texture should be an image of your grass looking at it from strait on at ground level. This image you will put in Photoshop and apply an alpha channel to.

Now back to Max, apply your material IDs to your grass mesh. then apply your material. Now apply the UVW map modifier to the mesh. The best and quickest way to apply your UVWs would be with the following steps----> Select the box map check box -----> then select the Shrinkwrap map check box ---> now check the box map check box again. That technique will insure that the map will be applied proportionally. Thats it! Now when you render the scene from a ground level view your grass should render fast and look alot more convincing.

The big bonus to this technique is that it works well even with smooth rolling surfaces.

 

Oh ya, one last thing, make sure your second texure is 2 sided.

 

[ May 09, 2002, 05:46 PM: Message edited by: Erik Lund ]

[nisus]

Hi Erik,

 

It idd sounds like a good technique for curved surfaces. gonna try that one

rgds

 

nisus

[scarp8]

Hi guys,

I'm with nisus, the plane technique has always worked for me. I, however, use "Forest Pack Lite". It's a free plugin from www.itoosoft.com

The full version opens up more possibilities.

 

Anyway, I've used Forest with free grass textures from Marlin Studios (http://www.marlinstudios.com) and got some incredible results.

 

Here's an image:

www.filmburn.com/contest.jpg

 

-Dave

 

-Dave

[yym]

 

[nisus]

Hello all,

 

It's great to see that all of you are sharing some very usuable techniques on making real grass.

Maybe we should make it a topic for a challenge one time!

Or we could exchange tips & techniques on other things too. Skies, Glass, Reflection, Water,...?

What do you think?

 

to scarp8: I can't link to your image. Anyone having this problem too? Feel free to mail this if you like.

 

to yym: I like your first image a lot. How did you create the grass? Maybe you could explain the technique you used.

 

rgds

 

nisus

[scarp8]

Sorry guys, I've been having trouble with my host. Try this: www.cgtoolbox.com/contest.jpg

[yym]

see this HTML Tutorials :

 

http://max3d.3dluvr.com/tutorials/ngrass

[plastic]

hi,

 

the scattered plane technique is a great idea.

i'm in the mood for writing a plugin script for automated grass generation.

it should work with a modified version of my tree shop plugin ( http://plugins.marclorenz.com )with added scatter functionality.

i would love to see more pictures/examples/scenes/settings. some problems i faced with my quick tests are visible plane borders and wrong shading.

the oren-nayar-blinn shader with roughness @ 100 seems to be the best for a plane-grass texture.

i am also thinking about a gradient opacity layer on top of the streched noise/bitmap opacity map.

please keep posting...

[STRAT]

Eric - spot on to you m8, superb idea.

 

im constantly comming up with opacity based ideas for my landscaping solutions. grass was going to be my next challenge. looks like you ust sorted my problem, tried it, it works wonders.

 

even with uneven hilly areas produced say in autocad, just imported into max, up'ed the meshing value and it works excellent.

 

thanks again

[DelfoZ]

First: Scuse my english

Second: This is my little contribution. i made one tutorial Grass tutorial . if this test can help to someone i will be happy

 

i know . u can do a better imagen with this Tip. i hope that .

[nisus]

Check this out: make grass script

 

http://www.cgarchitect.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=26;t=000009

 

tnx to quizzy

 

rgds

 

nisus

[Guest kaos]

hi, another way to do grass, which is similar to mapping it onto the actual grass surface is this one, that i used for 60 different house images we produced for a book...

 

Apply a (3ds max terminology, sorry) matte/shadow material to the ground geometry, and place the sky background in the environment, but edit the bg image so that there is also grass in the image, then it will render into the scene where the ground geometry is, and it will catch any shadows thrown its way....

 

Then its just a matter of adding some jaggies in ps to get that, grass against the kerb look........

 

or if you do not want to bring it into ps, then use a scattter of grass geometry against any walls and kerbs, also have these with the matte shadow material......

 

but, works best for eye level renders...

[Erik Lund]

Just a bit of helpfull info.

In the real world, there are on average 3,000 blades of grass in 1sq. foot of lawn.

I hope this helps you when trying to figure out the density for your grass creations.

[nisus]

Tnx for the tip Erik

[Cesar R]

Hello guys, I used the tutorial posted by yym, thanks btw yym, how big the plane and what are the scattering values ?

[nisus]

two of our grass images, made before the post of these tips

 

 

 

rgds

 

nisus

[nisus]

Hi all,

 

Here is a tut to make animated grass:

http://rd.bcentral.com/?ID=79496&s=7735509

 

rgds

 

nisus

[Alejandro Gonzalez @ Zerof]

If there are any Vray users out there. There is a *very cool way to make grass or hedge in a breeze. Create a simple plane, use Vray´s Displacement map modifier, jack a grass texture onto it and render away.

 

 

I wrote a simple explanation some time ago at vray.info:

 

http://www.vray.info/entry.asp?entryID=49

 

Hope it helps. Its quick, dirty and memory friendly, plus you dont get any clutter on your viewport.

 

[ September 08, 2002, 10:00 PM: Message edited by: Alejandro Gonzalez @ Zerofractal ]

[Dusk]

An alternative to scatter in MAX (but along the same lines) is to use a particle system. Make a blade (just a tall triangle extruded for example) and then create a PArray and select the grassy area as the emitter. Use the triangle as instanced geometry, and make sure it points the right way in respect to its pivot. That way you can set the viewport total low and keep the render total high, and you can vary the size, direction, etc. of the blades.

[Jeff Mottle]

A few more great tutorials on grass

 

http://3dtotal.com/ffa/tutorials/max/grass/grass1.asp

 

http://www.3dm-mc.com/tutorials/grass/