Google Maps and Google Earth are very common platforms today to explore maps and satellite images of the earth. But there are many other ways to explore the earth. Some are listed here. 1. Earth Explorer This map is developed by USGS helpful to obtain earth imagery across available geo-spatial data types. Users can navigate via interactive map or text search to obtain Landsat satellite imagery, Radar data, UAS data, digital line graphs, digital elevation model data, aerial photos, Sentinel satellite data, some commercial satellite imagery including IKONOS and OrbView3, land cover data, digital map data from the National Map, and many other datasets. Users can search by exact location via the interactive map or input specific coordinates to view what data types are available. 2. Sentinel Hub This platform developed by Sinergise has Sentinel, Landsat, and other Earth observation imagery easily accessible for browsing, visualization and analysi...
Geographic Coordinate System (GCS)
Most of the spatial data and maps of Nepal are based on two System.
1. Everest 1830 is mostly used in topographic maps and maps produced by governmental agencies like Department of Survey.
2. WGS84 is used in most of the images and maps available over the internet are referenced in this system.
Projected Coordinate System (PCS)
For Projection, the projection system used is Universal Transverse Mercator (UTM) which may be based on either WGS84 or Everest 1830.
Nepal lies in UTM zone between 44 and 45. The 44 zone covers western half of Nepal and 45 covers the eastern half. This projection is based on WGS84
Due to greater expansion in east-west direction of Nepal, Survey Department of Nepal uses Modified UTM (MUTM) for increasing accuracy in cadastral survey. Based on Everest 1830 the two zones are modified into three zones differentiated by longitude of the coordinate as 81, 84, and 87 covering west, central and eastern Nepal respectively.
Transformation between the two PCS
There is a slight difference between these UTM and MUTM system used in Nepal. We can do geographic transformation from one PCS to the other one by using following parameters:
Source GCS: Everest 1830 and Target GCS: WGS 1984
Method: Molodensky
Translation parameters:
Translation along X axis (in meters) = 293.17
Translation along Y axis (in meters) = 726.18
Translation along Z axis (in meters) = 245.36
Similarly, In order to do geographic transformation from WGS 1984 (Source GCS) to Everest 1830 (Target GCS) we use same method with same values with negative signs in front.
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