A geographic database is a database that is associated with a location on the earth in some way. In addition to this data, there is usually data called attribute data. Generally, attribute data is defined as other information that can be associated with spatial data. Divided into two categories: georeferenced data expressed in vector and raster format (including images), and attribute tables expressed in table form. Most GIS software applications focus on the use and management of vector geodatabases and raster geodatabase components.
Vector data. There are three types of vector data: point, line (or arc) and polygon data.
Point data
Point data is usually used to represent disconnected features and discrete data points. These points have no dimensions, so you cannot measure the length. Or the area with this data set. For example, schools, scenic spots, and the locations of bridges and culverts in the following examples. Point objects are also used to represent abstract points. For example, the point location can be a city or a place name.
Line data Line data (or arc) is used to represent line features. Typical examples are rivers, paths and streets. Linear objects have only one dimension, so they can only be used to measure length. The line object has a start point and an end point. Common examples are highway centerlines and hydrology. The most common symbols used to distinguish arcs are the line type (solid or dashed) and the use of a combination of line width and color. The black solid line is the street name, and the blue dashed line is the hydrographic name.
Polygon data
Polygons are used to represent areas such as city boundaries (on large-format maps), lakes or forests. Polygon features are two-dimensional, so they can be used to measure the area and perimeter of geographic features. Point feature data represents polygon data at a smaller scale. They help reduce confusion by simplifying data placement. As the object expands, the location of the school point is actually represented by a series of floor plans that indicate the physical location. The line features in the road centerline file only indicate the physical location of the road. When necessary, the curb width file is used to display the width of the street and any characteristics such as median and right of way (or sidewalk).
Raster Data
Raster data (also known as grid data) represents the fourth type of feature: surfaces. Raster data is cell-based and this data category also includes aerial and satellite imagery. There are two types of raster data: continuous and discrete. An example of discrete raster data is population density. Continuous data examples are temperature and elevation measurements. There are also three types of raster datasets: thematic data, spectral data, and pictures (imagery).
