Products >> Marine & Hydrograph >> Mapping Systems

GIS

Our GIS solutions provides the functions and tools needed to store, analyze, and display information about places. The key components of GIS software are:

	Tools for entering and manipulating geographic information such as addresses or political boundaries
	A database management system (DBMS)
	Tools that create intelligent digital maps you can analyze, query for more information, or print for presentation
	An easy-to-use graphical user interface (GUI)

Data Types and Models

Data for a GIS comes in three basic forms, all of which are demonstrated in the map to the right:

	Spatial data—what maps are made of Spatial data, made up of points, lines, and areas, is at the heart of every GIS. Spatial data forms the locations and shapes of map features such as buildings, streets, or cities
	Tabular data—adding information to maps Tabular data is information describing a map feature. For example, a map of customer locations may be linked to demographic information about those customers
	Image data—using images to build maps Image data includes such diverse elements as satellite images, aerial photographs, and scanned data—data that's been converted from paper to digital format

In addition, this data can be further classified into two types of data models

• Vector data model
  Discrete features, such as customer locations and data summarized by area, are usually represented using the vector model

• Raster data model
  Continuous numeric values, such as elevation, and continuous categories, such as vegetation types, are represented using the raster model

GPS

Differential correction techniques are used to enhance the quality of location data gathered using global positioning system (GPS) receivers. Differential correction can be applied in real-time directly in the field or when postprocessing data in the office. Although both methods are based on the same underlying principles, each accesses different data sources and achieves different levels of accuracy. Combining both methods provides flexibility during data collection and improves data integrity

The underlying premise of differential GPS (DGPS) requires that a GPS receiver, known as the base station, be set up on a precisely known location. The base station receiver calculates its position based on satellite signals and compares this location to the known location. The difference is applied to the GPS data recorded by the roving GPS receiver