Introduction to Geomatics and Basic Surveying
Geoinformatics or Geomatics
- Geo + information + matics
- Geoinformatics may be defined as the measurement and management of geoinformation.
Geoinformation: What is it?
- Any artificial or natural object/phenomenon on, below or above the surface of the earth.
- Examples:- Land parcels, roads, topography, forest, houses, river, flooding, glaciers, etc.
The fundamental divisions of Geoinformatics:
Measurement of Geoinformation
- Geometry: What is where?
- Identification: What is what?
Management of Geoinformation
- Management (storage, retrieval and presentation) of information.
- Manipulation (analysis based on information).
- Pacing, hands, guessing, rods
- Vedic age method of pacing
- Patwari measurement methods
- Nali, haath, etc.
- The human figure used mostly
Land surveying techniques
- Using chain and compass
- Using tape, chain, theodolite, etc.
- This technique is cumbersome and cannot be done in inaccessible areas.
- It needs substantial human dependence.
Electronic land surveying techniques
- Using EDMI and total station
- Using the robotic total station
- This technique is fast and accurate.
- It is difficult for inaccessible areas, as points are needed to be occupied.
- Initial uses of pigeon with the camera to spy on enemy terrain
- Using balloons
- Aircraft based
- Single photograph for interpretation
- Stereo for 3D model generation and measurement
- Analogue > Analytical > Digital photogrammetry
- It emerged during world war 1 and 2.
- Still, we used to fly to collect the data every time.
- It is a costly affair and may not be possible in bad weather.
Satellite remote sensing
- Commercial remote sensing is available since 1972.
- It is done from 600 km to 900 km altitude.
- It is used to get a synoptic view of terrain regularly in several wavebands.
- It offers km to m level spatial resolution.
- It is used for both measurement and identification of geoinformation.
Global Positioning System (GPS)
- It is an absolutely new concept to know one's location.
- In a GPS system, there are at least 24 earth-orbiting satellites; minimum 4 needed.
- One's position is known using the Geocentric coordinate system in a GPS system
- It can be done everywhere where the open sky is seen.
- It has thousands of applications.
Applications of Management of Geoinformation
- To store and retrieve information efficiently.
- To present information.
- To incorporate all information collected in analysis to suit the modern application
- GIS stands for Geographical Information System.
- GIS does all the management of geoinformation.
Examples of the use of GIS
Flood relief operation needs
- Flood extent
- Road network and types of roads
- Topography of land
- Distribution of pucca houses
- Distribution of one story or multi-story houses
- Distribution of probable shelters
- Locations of the rescue team
*Source- Internet, Books, Self-Analysis