1.1. Geodata and GIS Introduction, Users and Application Areas of Geodata

As Geodata we can define every dataset that has a spatial aspect or component. Synonyms are "spatial data", "geographic data", "geographic data sets" or "GIS data". The syllable "Geo" implies that the dataset has a spatial component that allows to georeference the described phenomena to a location or region on the earth. Strictly spoken, the term "geodata" only refers to data regarding our planet earth. For a more general term including other planets or outer space, the term "spatial data" can be used. For maximum benefit with regards to geographic analysis, geodata has a spatial, temporal and thematic aspect that allows to pinpoint a phenomena in space, time and topic. Unfortunately, not every spatial dataset also includes a temporal component. Geodata is the most important and often the most expensive ingredient of a geographic information system. It can be linked to other data sources using spatial, temporal or thematic relations. Based on geodata one can do queries, spatial analysis and simulations. Because geodata is often based on complex data structures, is complex and expensive to aquire and often accumulates larger amounts of data, geodata presents special challenges in information processing.

Often, people distinguish between spatial base data and thematic data. Both are subsets of the term "geodata". Geographic base data is usually provided by national or international surveying and mapping agencies and includes mainly topographic information stored in maps or landscape models. Satellite and Aerial images can also be regarded as spatial base data, as long as they only provide topographic information in the human-visible bands. Thematic data is aquired by specific domains. Thematic data can but does not necessarily have to include a geometry component. It is often linked to spatial base data using coordinates, administrative units, full addresses or zip codes. Examples include soil data, geology data, geostatistical data, weather data, etc.

Typical Thematic Layer Model in GIS (UNKNOWN)

Important Components of Geodata: Space, Time and Topic (PEUQUET 2002)

As a Geo Information System (GIS) we can define a computer-aided system for geographic data management, modeling, analysis, simulation and presentation. A GIS is an organized collection of computer hardware, software, geodata and skilled operators. More powerful GISoftware usually utilizes modern database technology or builds on spatial databases. GIS projects are application driven. More complex projects usually need a certain amount of customization and custom development and don't work with standard off-the-shelf GISoftware. While GIS needed very expensive hardware in the past, todays GISoftware works with standard PC workstations and peripheral devices. Hardware is usually the cheapest part of the system, software is often more expensive than the required hardware. Geodata and the wages of skilled operators are usually the most expensive parts of a GIS. There is no complete set of functionality that a GIS must provide and the functionality of a GIS can be theoretically be infinitely extended.

Components of a GIS

Geodata is widely used as an ingredient for modeling, analysis, simulation and presentation purposes in many domains. Estimates vary, but it is widely believed that around 80 to 90 percent of todays digital data has some spatial component or can be linked to existing geodata. Following is a table of potential user groups and usage scenarios. Naturally, it is only a short of list of more popular applications and by no means complete.

Table of Geodata Usage Groups and Usage Scenarios