Preparation of a Base Map which shows the details of topography, geology, politics and other cadastral information is called Base Mapping . Base Mapping is the creation of most perfect spatial database in the system of data given.
Steps of Base Mapping :
• Acquisition of an imagery: This is the first step for base mapping . These imageries are processed and data are attached to form the Base Map . The different types of imageries used for Base Mapping are:
1. Aerial photo: Both black and white and color aerial photographs can be used for Base Mapping . Color aerial photographs are recent inventions.
2. Aerial Triangulation Scans; These are the soft copy product of aerial photos. It consists of aerotriangulation data.
3. Orthophotos: When all geometrical errors are corrected in an aerial photography it is called orthophoto which can also be used for Base Mapping .
4. Satellite Imagery: Imageries of earth surface captured by camera mounted on satellites are called satellite imagery which can be used for Base Mapping .
5. Simple maps with physical outline: This type of maps are used at a more generalized level, for example a outline map of India showing the state, national and international boundaries may be scanned and used for Base Mapping which will show simple features like states of India.
• Digitization and Region creation: This step of Base Mapping comes after choosing of map. The raster maps are vectorized and depending upon the purpose of the Base Map , the areas, boundaries, special features like roads are digitized. Digitization means saving the features in the map in a discrete set of points. Once the digitization is over , regions are created.
• Map Data: Once the imagery is selected then data are attached to the maps. Data related to geology, physical land cover, land use, topography and political boundaries, places of significance are all attached to the maps. Different colors are used for different features which makes the map interesting. A map legend is attached to the map so that the features can be identified easily even by the lay man. Data attachment is done using different layers.
• Leveling the map: Once the data are attached, places, roads, special features and others are labelled so that it becomes easy for a layman to understand the map. A key is also given at the side of the map which has all the signs and color used in the map for reference to the user. Geographical names are also given to the map which helps a student or a researcher.
Use of Base Mapping :
• Used for reference by the students or researchers for their projects or during their training. The map is true to scale, so it is often attached with their research works or term papers.
• Base Mapping is used for political purposes. Since the map contains all the basic data and is properly labelled it is used by political leaders during voting campaigns or for implementation of any rule in a particular area.
• Base Mapping has an important use in constructional works. The engineers, planners use the Base Map to know about the site before doing any constructional activity.
• Tourists use Base Map to know the area they are travelling. So Base Mapping is also used in tourism.
Besides, Base Mapping has a number of uses which is not possible to list out. Base Mapping is becoming popular day by day and use of Base Mapping is expected to increase in coming years.
GPS Survey Equipment