Grass. In the scene, the plane is 33000x45600mm on which the grass is planted. Per square is turned off, turn it on if necessary. The archive contains a file with the configured corona scatter for seating as in the preview.
3ds max 2014, fbx, mtl, mat, textures, screenshots-scatter settings.
More grass models:
https://3dsky.org/3dmodels/show/grass_lawn 
https://3dsky.org/3dmodels/show/trava_gazon_1 
https://3dsky.org/3dmodels/show/vesennii_lug_trava 
https://3dsky.org/3dmodels/show/forest_grass 
https://3dsky.org/3dmodels/show/trava_strizhenyi_gazon 
https://3dsky.org/3dmodels/show/polevye_travy_2_trava_1 
https://3dsky.org/3dmodels/show/forest_grass_2_2