The accuracy of measurements , e.g., of distance, done on a map is affected by the type of map projection used to draw this map. The accuracy with which a given map scale can depict the location and shape of map features is known as resolution . The larger the map scale, the higher the possible resolution. As map scale decreases, resolution diminishes and feature boundaries must be smoothed, simplified, or not shown at all. Resolution plays a large role in GIS, especially in raster-based modelling.
Resolution plays a large part in the ability of a map to accurately describe the earth s features.
It is essential that the user be mindful of the scale of the data layers. Serious errors can result if the theme lacks sufficient resolution to effectively describe an area of interest. A GIS does not tell its user that she has made an error in choosing the right data layer for her project. Topology Topology is a mathematical procedure for explicitly defining spatial relationships . Arc-Node Topology Points along the arc that define its shape are called vertices .