What is GPS?

What is GIS?

What is CAD?

Remote Sensing

Geospatial Analysis

Vegetation Mapping

Surface Modeling

Satellite Imagery

Scientific Papers

Geographic Information Systems (GIS)

GIS is a system for creating and managing spatial data and associated attributes. In the strictest sense, it is a computer system capable of integrating, storing, editing, analyzing, and displaying geographically-referenced information.

In a more generic sense, GIS is a "smart map" tool that allows users to create interactive queries (user created searches), analyze the spatial information, and edit data.

Geographic information systems technology can be used for scientific investigations resource management asset management development planning , cartography and route planning. For example, a GIS might allow emergency planners to easily calculate emergency response times in the event of a natural disaster , or a GIS might be used to find wetlands that need protection from pollution. GIS data represents real world objects (roads, land use, elevation) with digital data.

Real world objects can be divided into two abstractions: discrete objects (a house) and continuous fields (rain fall amount or elevation). There are two broad methods used to store data in a GIS for both abstractions: Raster and Vector.

Raster Data

Raster data type consists of rows and columns of cells where in each cell is stored a single value. Most often, raster data are images ( raster images), but besides just color, the value recorded for each cell may be a discrete value, such as land use, a continuous value, such as rainfall, or a null value if no data is available. While a raster cell stores a single value, it can be extended by using raster bands to represent RGB (red, green, blue) colors, color maps (a mapping between a thematic code and RGB value), or an extended attribute table with one row for each unique cell value. The resolution of the raster dataset is its cell width in ground units. For example, one cell of a raster image represents one meter on the ground.

Vector Data

Vector data type uses geometries such as points, lines, or polygons, also called areas (shapes bounded by lines), to represent objects. Examples include property boundaries for a housing subdivision represented as polygons and well locations represented as points. Vector features can be made to respect spatial integrity through the application of topology rules such as 'polygons must not overlap'. Vector data can also be used to represent continuously varying phenomena. Contour lines and triangulated irregular networks (TIN) are used to represent elevation or other continuously changing values. TINs record values at point locations, which are connected by lines to form an irregular mesh of triangles. The face of the triangles represent the terrain surface.