Introduction to Geospatial Data

Geospatial data has information about the locations and characteristics of natural features such as mountains, rivers, lakes, oceans, faults, islands, continents, ores, geological formations, volcanoes,earthquakes, tectonic plates and natural fire, floods, land slides and mod slides. In addition, it has information about cultural features such as roads, freeways, highways, houses, stores, shopping centers, hotels, zoning, states, cities, counties, federal districts, countries, neighborhoods, and city parks. A GIS software, such as ESRI ArcView, can create, store, display and analyze these data. Terra bites of geospatial data exists that cane be used to determine patterns, trends and relationships among features that can used to create information to solve myriads of natural, social and economic problems.

Natural and Cultural Features

The image above contains many houses that are located in the valley at the foot of the Santa Monica Mountains. The natural features consist of variety of vegetation, slope of various degrees and soil of different kinds, mountains and clouds. Examples of culturall features are houses, roads, water and utility systems. The image is a raster data format that can be changed to a vector data format as different layers that can be displayed and analyzed in a GIS software.

Visible and Invisible Features

What are not seen in the picture to the left are featutes underneath the surface such as rock formations, utility lines, soil type, water beds, and geological history. All the data from the core of the earth to the Sun has impact on what is seen in this picture and can be translated to a layer in a GIS software and viewed and analyzed. A house is an excellent example of a cultural feature, and usually points of different sizes and shapes are used to represent them on a GIS layer. Area features such as lakes and city parks are represented using polygons, and linear features such as roads and streets are represented using lines of different styles.

Point, Linear and Polygon Geometries

The houses location information such as longitude and latitude is used to repesent them on a digital or paper map. This location information can be accompanied by many attribute information such as price, type, age, ownership in a GIS software. The houses are represented using poits of various sizes and shapes. The linear featute such a streets, roads, streams, faults, utility lines, are represented using lines. Area features such as city parks and vagetation are represented on the map using polygon geometry.

Representing Natural and Cultural Features

This image on the right by ESRI shows how similar features occupy their own layers. Trees in one layer, streams in one layer and vegetation in another layer. By creating layers that represet the same features, we can put transparent layers on top of each other and view and analyse trends, pattern and relationship among them. In this example we can see three layers of streams, old growth tree and soil. Then we can see if there is a relationship between soil type and trees or the pattern of tree distribution along the stream, among many others.

An Example of GIS Layers in a GIS Software

This is an example of hundred of layers that can be incorporated in a GIS project. Layers can be geology, hydrology, land use, vegetation, topography, flood zones, superfund sites and houses and stores. Numbers such as population of cities, counties, countries also can be mapped viewed and analysed. By combing layers of satellite images, topographic maps, surveying data, and census data, GIS layers and GIS software present powerful tool to provide solutions to countless problems.

An Example of GIS Software Interface.