Nurbs are not adapted for this sort of thing ;)
ELse you must draw each blade of grass! Ask a random position of each blades!
Better is apply a texture of grass on a volume with different technic, Bump mapping, particules, fur&grass plugin etc...:)
It's more polygons modeling
http://www.google.fr/images?hl=fr&q=texture%20of%20grass&um=1&ie=UTF-8&source=og&sa=N&tab=wi&biw=1024&bih=603

http://www.pxleyes.com/video-tutorial/blender/8221/Making-Grass-with-Particles.html

A crazzy one Plugin by tak2hata in Sketchup! (it's free! ) It's amazing!
http://forums.sketchucation.com/viewtopic.php?f=323&t=28092
http://sketchupdate.blogspot.com/2010/05/having-spent-last-three-hours-fiddling.html
By Rico91

Hi Tony, yeah something like blades of grass tend to be better added in by some render-specific tools in your rendering program rather than trying to explicitly model them by drawing them directly.

It can be possible to adapt a hair or fur rendering system to generate blades of grass on an object at render time, if your rendering program has such a module.

There are also some polygon modeling programs that have some mechanisms to automatically create stuff like that - that plug-in that Pilou mentioned for SketchUp, and also there is a program called Vue which is focused on generating all kinds of natural scenes, that may be of use: http://www.e-onsoftware.com/

MoI itself is much more focused on drawing things directly, but for blades of grass you really don't want to try and draw each one of those directly.

- Michael

Bryce is another (very inexpensive) nature/landscape-specific modeler/render program that I use occasionally.

http://www.daz3d.com/i/software/bryce7?_m=d

Oh no! It's the Furrari again.

Or is that a Lamb-orghini?

Ed

Thanks to all the ideas I have explained
unfortunately my software rendering does not contain
displacement maps so I wanted to create a
pattern of light in which you put on a nurbs texture of grass

Hello

Hi Tony, I'm sorry I'm not quite sure what you mean by a "pattern of light in which you put on a nurbs texture of grass", could you maybe describe that some more?

But it's hard to get a good appearance of grass just by a flat texture map. I think for best results you don't even want to use a displacement map for it - you want to have actual polygon geometry created for the grass but for things like that it's better to have the geometry created by an automated mechanism that will generate the geometry according to some parameters that you give it. That's how a hair or fur rendering system will usually work.

- Michael