Extent, grain and resolution. Possible alternative measures of scale. A, the extent is the interval of observation, which determines the largest scale observable; B, the grain is the fineness of obser vation, which determines the smallest scale observable. C, the resolution is often equated with the grain, but clearly, this can be misleading as the resolution can be finer than the grain Extent 3 Grain "γ ResolutionExtent, grain and resolution. Possible alternative measures of scale. A, the extent is the interval of observation, which determines the largest scale observable; B, the grain is the fineness of obser￾vation, which determines the smallest scale observable. C, the resolution is often equated with the grain, but clearly, this can be misleading as the resolution can be finer than the grain. Extent Grain Resolution