#Raster data models software#

Three basic data structures are - Relational, Hierarchical and Network. Many GIS software's have specialized capabilities for storing and manipulating attribute data in addition to spatial information. The choice of data structure affects both Data storage volume and processing efficiency. There are number of different ways to organize the data inside the information system. Figure 2: Layers and Coverage concept in GIS

The Figure 2 shows layers and coverage concept in GIS. But it is possible for each region to have multiple attributes. The characteristic of each layer within a layer-based GIS is that all locations with each layer may be said to belong to a single Arial region or cell, whether it be a polygon bounded by lines in vector system, or a grid cell in a Raster system. The layers can be combined with each other in various ways to create new layers that are a function of the individual ones. The concept of layers is to be found in both vector and raster models. The common requirement to access data on the basis of one or more classes has resulted in several GIS employing organizational schemes in which all data of a particular level of classification, such as roads, rivers or vegetation types are grouped into so called layers or coverages. Figure 1: Vector and Raster data examples Modern GIS packages are able to handle both models. Both the vector and raster models for storing geographic data have unique advantages and disadvantages. A raster image comprises a collection of grid cells rather like a scanned map or picture. The raster model has evolved to model such continuous features. The vector model is extremely useful for describing discrete features, but less useful for describing continuously varying features such as soil type or accessibility costs for hospitals.

#Raster data models software#

Spatial analysis is difficult with respect to writing the software program. Vector data models require less storage space, outputs are appreciable, Estimation of area/perimeter is accurate and editing is faster and convenient. Connecting set of line segments forms area objects. Vector data model uses line segments or points represented by their explicit x, y coordinates to identify locations. Figure 1 shows vector and raster data representation of the real world phenomena. Raster data models require a huge volume of data to be stored, fitness of data is limited by cell size and output is less beautiful.

Raster models are simple with which spatial analysis is easier and faster. One set of cell and associated value is a LAYER.

Each cell contains a single value and every location corresponds to a cell. In raster type of representation of the geographical data, a set of cells located by coordinate is used each cell is independently addressed with the value of an attribute. Data models discussed here are for representing the spatial information.Дata models are of two types: Raster and Vector. It represents the linkage between the real world domain of geographic data and computer representation of these features. Conversion of real world geographical variation into discrete objects is done through data models.