slgrid

SL Grid

Sri Lankan Grid

GPS (Global Positioning System) are using WGS 84 as their default coordinate to locate universally. Though WGS (World Geodetic System) 1984 is the world standard of Coordinate System. If you have ever used GoogleEarth with GPS you will be surprised to how well are they matching. Many countries are having their own way of representing the location via coordinates on their terrotory using often a simplified unambiguous way to use the Grid.

Sri Lankan Grid system makes use of an ellipsesoid the goes through the crest of the Mount Piduruthalagala (The highest mountain of Sri Lanka which is 2524m high above sea level) as the virtual reference using the coordinates 200000 E, 200000N (where E stands for Easting and N stands for Northing) in such a way that every unit stands for 1m (so that you won't get anything negative in the down south say for example Hambantota)

Earth is orbiting the Sun in an elliptical path thats why when we are closer to the sun we are in the summer season when we are further away we have rainy season in between we have fall (Autum) and winter. Earth is more close to ellipsoid than a sphere. when we make 3 dimensional globe to 2 dimensional maps we need projection. Best projection for Sri Lanka is the one ellipsoid goes through the Mount Everest is known as the SL Grid and aka (Also known as) Kandawala. In the ArcGIS 9.1 you will find Kandawala tranformation in the Arc View 3.2a you will not find but we can achive the results using a mathematical transformation (Dont' worry computer is there do transformation we just need give the values)

Transform the WGS to SL Grid

Projection: Transverse Mercator

Spheroid: Everest (If Everest is not there use WGS 84)

Central Meridian: 80.7717111

Reference Latitude:7.00048028

Scale Factor:0.99992384

False Northing: 200000

False Easting: 200000

To configure it in ArcView 3.2a have a look at http://geocities.com/umapathyxp/gis.html

If would like to make comments and suggestion more than welcome. send an email to umapathyxp@gmail.com