Ahasanul Hoque

Ahasanul Hoque

Lives in Bangladesh
Ahasanul Hoque

Bangladesh Map Projection Systems with Parameters

April 23, 2017, by aHaSaN, category Geospatial & Environmental Job

Bangladesh’s longitude is from about 88º East to about 92º East. As UTM uses 6º band on longitude to divide the earth into zones, Bangladesh falls into two different UTM zones: Zone 45 N (West of 90º E) and Zone 46 N (East of 90º E). However, the parameter values that characterize a UTM zone are varies with zones. Therefore, issue arises in terms of projection accuracy when user goes for mapping the area of Bangladesh that falls in both 45N and 46N UTM zones (e.g., the whole Bangladesh Map). To solve this issue, in Flood Action Plan 19 (FAP 19) study a new projection system was evolved from the UTM, and is known as BTM projection system. Usually, the mid longitude of a Zone is taken as the central meridian in UTM. For example, if user choose Zone 45N, the central meridian should be 87º East, while if s/he choose UTM Zone 46, the central meridian should be 93º East. Therefore , the geo-spatial expert in Bangladesh have been using different projection parameters to create maps. There are numerous map projections being used in Bangladesh. The following is a list of known map rojections their parameters, and their known users, or uses. Hope this will solve the issue of map projection for Bangladesh and help the spatial people.

Name: TM (Transverse Mercator)
User/ers: SPOT XS Satellite images, FAP6
Spheroid: Everest (probably 1830)
Central Meridian: 90 ° E of Greenwich
Latitude of Origin: 0° (the equator)
False Northing: 0 meters
False Easting: 500,000 meters
Scale Factor: 0.9998

Name: Universal Transverse Mercator (UTM) Zone 45N
Projection: Transverse_Mercator
False_Easting: 500000.0
False_Northing: 0.0
Central_Meridian: 87.0
Scale_Factor: 0.9996
Latitude_Of_Origin: 0.0
Linear Unit: Meter
Zone: Zone 45
Datum: WGS1984
Spheroid: WGS1984

Name: Universal Transverse Mercator (UTM) Zone 46N
Projection: Transverse_Mercator
False_Easting: 500000.0
False_Northing: 0.0
Central_Meridian: 93.0
Scale_Factor: 0.9996
Latitude_Of_Origin: 0.0
Linear Unit: Meter
Zone: Zone 46
Datum: WGS1984
Spheroid: WGS1984

Name: Bangladesh Universal Transverse Mercator (BUTM)
Projection: Transverse_Mercator
False_Easting: 500000.0
False_Northing: 0.0
Central_Meridian: 90.0
Scale_Factor: 0.9996
Latitude_Of_Origin: 0.0
Linear Unit: Meter
Datum: WGS1984
Spheroid: WGS1984

Notes: Regular UTM splits Bangladesh in two at 90° E; a modified system is used to cover all of the country – BUTM.

Name : Bangladesh Transverse Mercator (BTM)
Projection: Transverse_Mercator
False_Easting: 500000.000000
False_Northing: ¬2000000.000000
Central_Meridian: 90.000000
Scale_Factor: 0.999600
Latitude_Of_Origin: 0.000000
Linear Unit: Meter (1.000000)

Geographic Coordinate System: GCS_WGS_1984
Angular Unit: Degree (0.017453292519943299)
Prime Meridian: Greenwich (0.000000000000000000)
Datum: D_WGS_1984
Spheroid: WGS_1984
Semimajor Axis: 6378137.000000000000000000
Semiminor Axis: 6356752.314245179300000000

Notes: Same as BUTM except False northing is -2,000,000.

Name: LCC1 (Lambert Conformal Conic- Standard Parallel) 

User/ers: Panchromatic Sat-photos SSC, LGED maps

Projection: Lambert Conformal Conic
False Easting: 2743185.699 Meters
False Northing: 914395.233 Meters
Central Meridian: 90.0 (DD)
First Standard Parallel: 23.15 (DD)
Second Standard Parallel: 28.80 (DD)
Latitude of Origin: 26.00 (DD)
Linear Unit: Meter
Datum: Everest_1830 or D_Everest_Bangladesh
Spheroid: Everest_1830 or Everest_Adj_1937

Notes: This is the same as the Indian Zone IIB Grid. According to Northwest Hydraulic Consultants & Finn map this is a LCC of the one standard parallel type.

Name: LCC2 (Lambert Conformal Conic – Two standard Parallels)
User/ers: aviation charts
Spheroid: (Everest 1830)
Standard Parallels: 170 20’ N 220 40’ N
Convergence Factor: 0.34215

Notes: Information on aviation charts from Northwet Hydraulic Consultants

Name: India Zone IIB Grid (is a LCC projection)
Uses/ers: SOB Maps
Spheroid: Everest 1830 or Malaya RKT Len.
semi-maj axis: 6974310.6 yards
Sq. of eccentricity: 0.00663784663
Central Meridian: 900 E of Greenwich
Latitude of Origin: 260 N (Standard Parallel)
False Northing: 1,000,000 Indian yards
False Easting: 3,000,000 Indian yards
Scale Factor: 0.998786408

Notes: This is the same as LCC1 (with a single standard parallel) Information provided by British Directorate of Military Survey Plans (as recorded in Northwest Hydraulic Consultants documents). It is not clear which Everest spheroid is used many assume it is the 1830 but some think it is Malaya RKT. The Indian yard is equal to 0.91439523 meters. The southern tip of Bangladesh (Cox’s Bazar south) maybe in the IIIB Grid (according or aviation charts but not SOB maps).

Name: India Zone IIIB Grid (is a LCC projection)
Uses/ers: SOB maps
Spheroid: Everest 1830 or Malaya RKT Len.
semi-maj axis: 6974310.6 yards
Sq. of eccentricity: 0.00663784663
Central Meridian: 1000 E of Greenwich
Latitude of Origin: 190 N (Standard Parallel)
False Northing: 1,000,000 Indian yards
False Easting: 3,000,000 Indian yards
Scale Factor: 0.998786408

Notes: This grid may only apply to the southern tip of Bang1adesh (Cox’s Bazar south), according or aviation charts, but not SOB maps. This is also a Lambert Conformal Conic with one standard parallel Information provided by British Directorate of Military survey Plans (as recorded in Northwest Hydraulic Consultants documents) It is not clear which Everest spheroid is used many assume it is the 1830, but some think it is Malaya RKT. The Indian yard is equal to 0.91439523 meters.

A helpful video tutorial on YouTube for converting BTM to WGS84 in ArcGIS Platform

So, what do you think ?