Base Map is primary graphical representation of selected fundamental existing map pattern. In planning process, base map provides foundation and initial identification of spatial objects of area for creating analysis and additional data of a proposal can be compiled. Example of Base map: a primary map of major natural and man-made features such as bodies of water, Roads, buildings, and municipal, boundaries. Etc.
What is the scale of a base map?
- Contents of Base map
- Type of scale on map document
- Legend in Base map
Base maps can be of various scale for example regional level base map, City level base map, Local area base map, layout base map etc. the data shown in various scale (regional, city etc) base map is also different from another, for example a depth of detailing of data is high in city base map but low in regional base map.
What is a data sources of base map?
The data source for various level of map is different from another, the regional base map will have state roads, districts roads boundary etc, but city level base map will have parks, city roads, plot boundary etc details.
Existing copy of Maps, for example – state boundary, Administrative boundary map, forest department map, public work department map, Cadastral sheet map, etc.
High resolution satellite imagery and aerial images, photogrammetric imagine methods.
Field survey mainly to validate existing landmarks, boundary, roads, river etc.
Contents of Base map
Regional of district level base map:
The regional level base map is prepared for any demarked region or for district at broader scale.
Demarcated Boundary: demarcated boundary refers to the boundary of states, boundary between two districts and regions, sub districts or Taluka boundary small villages’ boundary etc.
Transportation networks: Railway lines passing through region, Regional base map will have National highway road network in base map area, state highways, district roads, other roads. Etc.
Topography and major land use: the topography includes hill area, contours, mines, etc. and major land use includes forest land, water reservoir, river flow, canal etc.
Settlements and landmarks: urban and rural settlement and major district landmarks like district headquarters, major office location, courts, and rural administrative office location.
For city/ ward/ area level base map :
The city level base map is includes details than regional base map,
boundaries: City boundary, Metropolitan boundary, urban area boundary, municipal boundaries and ward boundaries, electoral ward boundary ward, settlement within the municipal limits, cantonment area boundary (if cantonment situated in city area).
Transportation networks: Railway lines passing through region, metro or local rail line (if available in city limit) Regional base map will have National highway road network in base map area, state highways, district roads, arterial road, sub arterial road, collector roads, and local roads.
Landmarks and important places: Hills, water bodies, Rivers and streams, canals, lakes, swamps, marshy lands, Religious places such as temples, mosques, churches, playground, social halls, stadium etc. administrative building, historic building, bus stop, bridges, squares etc.
Contours in city limits.
The layout planning level base map:
The layour level base map includes, all the site amenity such as Trees, vegetation (all kind), water body, all road access to site, building along the surrounding of the site, electric lines, electric ploes, water supply, sanitation line slope contours of site, existing features such as building structure, rocks on site, holes, wall etc.
Type of scale on map document
Fractional or Ratio Scale:
The most used scale on map document in urban planning is Fractional or Ratio Scale, A fractional or ratio scale of map shows the fraction of a land feature on the map( with respect to ratio or fraction). For example let’s say the scale of the map is 1:50000. It represents the map scale as a mathematical ratio or fraction. It can be also shown as 1/50000 as well. It means that one unit of measurement on the map is equal to 50000 of the same unit on the ground. The unit can be centimetre, meter, feet, inches, etc. it also concludes that any distance on the map is 1/50000 of its true value on the ground.
Linear scale also known as scale bar, linear scale is the relationship between distances on the map and the real world. A linear scale shows the distance between two or more prominent landmarks or points.
Verbal Scale is the type of scale use simple words to describe a prominent surface feature. For example “1 centimetre on the map represents 500m on the ground” is a verbal scale. That means the distance of 1cm on the map corresponds to 500m on the earth’s surface.
Legend in Base map
Since the map is graphical representation of real ground data, so symbols and Legends are used to represent the ground real objects. The Legend help us to read map by graphical key symbols. It also give information represented on map to understand the given map.