Introduction of GIS related concepts

Geographic Information System (GIS). It is a specific and very important spatial information system. It is a technical system to collect, store, manage, calculate, analyze, display and describe the geographical distribution data in the whole or part of the earth surface, air and underground space supported by computer hardware and software system.

Grasp GIS basic concepts

GIS Basic Concepts

OGC standards?

The OGC is the Open Geospatial Consortium. It is a non-profit, international, voluntary, and voluntary standardization organization. Its main purpose is to develop standards related to spatial information and location-based services. These standards are the “products” of OGC, and the purpose of these standards is to allow different vendors and products to interoperate through a uniform interface. Common criteria for definition:

  • WMS
  • WMTS
  • WFS

Tiled layers?

A map tile is a map slice file containing a series of scales within a certain map area. Map tiles are organized according to a pyramid structure, and each tile is uniquely identified by rank, row and column number. When panning and zooming the map, the browser calculates the required tiles according to the pyramid rules, obtains them from the tile server and splices them together. Map tile is an optimization strategy to improve the user experience of map browsing.

Vector layers?

XYZ data source?

XYZ: Where XY is the coordinate and Z is the level at which the map can be scaled.

Refer to two GIS data source providing systems:

EPSG?

EPSG Defines Coordinate Systems Worldwide, European Petroleum Survey Group in Chinese. The group was established in 1986 and merged into the InternationalAssociation of Oil & Gas Producers in 2005. Each part of the world is mapped by the EPSG, but the map is different because of the different coordinates.

  • EPSG:4490

IO /4490 China Geodetic Coordinate System 2000: China Geodetic Coordinate System 2000

  • EPSG:4326

In terms of World maps, EPSG:4326 is one of the more famous because it is used by the U.S. -led GPS System. It is also better known as WGS84. WGS(World Geodetic System) is the World Geodetic System, which was defined in 1984. That’s why it’s called WGS84.

  • EPSG:3857

Another well-known code is EPSG:3857, which is also a map of the world, currently is mainly the major Internet map companies to it as a benchmark, such as Google maps, Microsoft maps are using it.