The Logical moddel is how the data is presentet to the user ther are two key tgyes namely 1. Raster Data 2. Vector Data Although Entity-based modelling is often preserved as vector data and Field-based modelling is preserved as raster data this is not a absolut, Ther are many applications where representing Entity-based modelling as raster is the natural choice, especially if the enteties are derived form satellite data through a classification process. like wise Field-based modelling is often represented as measurement points or isolines using vector data