GIS, Map Projection and Coordinate System
What is Geographical Information System (GIS)?
According to Wikipedia it is a system designed to capture, store, manipulate, analyze, manage, and present all types of spatial or geographical data. We can make web maps using different kinds of GIS data. The question is that what we have to do with the map so that we can publish it online through your unique URL.
In order to do GIS you can use QGIS, an open source GIS software with a lots of great GIS features. When we are working on GIS projects where we only get some very raw data and will think about GIS software to store, manipulate and analyze the data.
Map Projections:
It is impossible task to create maps without map projections. We need systematic transformation of the latitudes and longitudes of locations from the surface of a sphere or an ellipsoid into locations on a plane, which is referred to as map projection. The surface in some fashion may get distorted by map projections. Following are some different types of map projection:
- Cylindrical.
- Pseudo cylindrical.
- Conic.
- Van der Grinten.
- Pseudo conic.
Coordinate system:
A coordinate system is a system that uses one or more numbers, or coordinates, to uniquely determine the position of the points or other geometric elements on a manifold such as Euclidean space.
The question is why do we need a coordinate system? The biggest reason is that we need to connect different pictures together. Think of Google Maps. It is a web environment representing a big map of the world. In reality this map is a byproduct of satellite map. The satellite images are converted into a map by stitching them together at different times. Here coordinate system comes into the picture because we embed a coordinate system into an image and assign every pixel of the image a unique x and y value.