Several methods, inside 3ds Max, were used to achieve an high level of dirt detail. Advanced Materials – Mix of Composite, V-Ray Dirt and V-Ray Blend Materials. General grass distribution created with Multiscatter and MultiscatterMask. Probably a good scene to learn dirt and grass methodology, mood aspects, or even create commercial spots, walkthroughs, flythroughs or use it e.g. as a car environment scene.